Probe

Abstract

To provide a detector that increases the opportunities to receive radar waves from speed measuring devices. [Solution] The detector 1 is installed in a vehicle and detects radar waves from a speed measuring device. The detector 1 comprises a receiving unit 21, a receiving detection unit 22, and a refining unit 51. The receiving unit 21 includes an antenna. The receiving detection unit 22 generates an intermediate frequency signal while sweeping a predetermined frequency range fb to a terminal frequency fe, and detects radio wave reception based on the intermediate frequency signal. After the receiving detection unit 22 has swept to the terminal frequency fe, the refining unit 51 determines whether the radio wave reception detected by the receiving detection unit 22 is the reception of radar waves from a speed measuring device. The refining unit 51 determines whether a predetermined number of radio waves with high radio wave intensity levels among the radio waves detected during the sweep are the reception of radar waves from a speed measuring device.

Description

Technical Field

[0001] The present invention relates to a detector capable of receiving a radar wave irradiated by a speed measurement device.

Background Art

[0002] When a vehicle approaches a speed measurement device or the detector receives a radar wave, which is a radio wave irradiated by the speed measurement device, the detector notifies information that directly or indirectly encourages speed compliance. This detector notifies the information by receiving the radar wave irradiated by the speed measurement device with an antenna. Further, the detector detects that the position of the host vehicle specified by GPS has approached a predetermined distance from the position of a speed measurement device registered in advance, and notifies the information.

[0003] This detector can detect microwaves in the X band, microwaves in the K band, and the like. For example, this detector includes a first local oscillator and a first mixer. A first frequency signal is generated by the first local oscillator, and a first intermediate frequency signal is generated by mixing the received signal and the first frequency signal in the first mixer. Then, the detector includes a detection unit that detects the radar wave of the speed measurement device from the first intermediate frequency signal.

[0004] In recent years, detectors have included a double superheterodyne type receiving circuit (see, for example, Patent Document 1 and Patent Document 2). A detector of the double superheterodyne type further includes a second local oscillator, a sweep control unit, and a second mixer for image suppression. The second local oscillator is a voltage controlled oscillator (VCO) that generates a second frequency signal corresponding to the voltage input from the sweep control unit. The sweep control unit repeatedly sweeps the second frequency signal output by the second local oscillator within a predetermined frequency range by sweeping the voltage input to the second local oscillator. The second mixer generates a second intermediate frequency signal by mixing the second frequency signal and the first intermediate frequency signal. The detection unit performs detection using this second intermediate frequency signal.

[0005] However, double superheterodyne detectors receive radio waves in the same frequency band emitted by devices other than speed measuring devices. These detectors may mistakenly identify these waves as signals from the speed measuring device. Therefore, the detector scrutinizes the received radio waves to suppress misidentification of signals emitted by devices other than speed measuring devices.

[0006] If radio wave reception is detected during a sweep by the second local oscillator, the sweep is temporarily paused. The second local oscillator then fixes the frequency of the second frequency signal for a certain period of time. During the sweep stop period when the frequency is fixed, a refinement process is performed on the radio waves to suppress misidentification. In this refinement process, for example, the continuity of the received signal is determined. A received signal that continues for a certain period of time or longer is determined to be a signal originating from the radar wave of the speed measuring device and is subject to information broadcasting. If the duration of the received signal is less than a certain period of time, the sweep stop is released and the sweep resumes from the fixed frequency. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2017-96728 [Patent Document 2] Japanese Patent Publication No. 2022-139870 [Overview of the project] [Problems that the invention aims to solve]

[0008] If the vehicle is far from the speed measuring device, the probability of an obstruction between the vehicle and the device increases, which can result in the radar wave not being received at the wrong time. To improve the chances of the speed measuring device receiving radar waves, one possible solution is to shorten the cycle time between the start of one sweep and the start of the next.

[0009] When a radio wave is detected and a sweep stop occurs, the sweep cycle time is prolonged. If the number of radio wave receptions during a single sweep is small, the impact of sweep stops for refinement on the cycle time is minimal. However, in some locations, dozens of radio waves may be detected during a single sweep. This results in dozens of sweep stops occurring before a single sweep is completed. The prolongation of the sweep cycle time is significant, and the opportunity to receive radar waves from the speed measurement device is greatly diminished.

[0010] For example, in areas where many vending machines are installed and many vehicles are driving around emitting radio waves to detect vehicles and obstacles ahead and measure distance, these radio waves often have frequencies that fall within the sweep frequency range, and it is possible to detect dozens of radio waves during a single sweep.

[0011] The present invention was proposed to solve the problems of the prior art described above, and its objective is to provide a detector that increases the opportunities for receiving radar waves from a speed measuring device. [Means for solving the problem]

[0012] To achieve the above objective, the detector according to the present invention is a detector installed in a vehicle that detects radar waves from a speed measuring device, and comprises: a receiving unit including an antenna; a receiving detection unit that generates an intermediate frequency signal while sweeping a predetermined frequency range up to a terminal frequency and detects radio wave reception based on the intermediate frequency signal; and a refining unit that, after the receiving detection unit has swept up to the terminal frequency, determines whether the radio wave reception detected by the receiving detection unit is the reception of radar waves from the speed measuring device, wherein the refining unit determines whether a predetermined number of radio waves with high radio wave intensity levels among the radio waves detected during the sweep are the reception of radar waves from the speed measuring device.

[0013] The aforementioned inspection unit may determine whether a predetermined number of radio waves with high signal strength levels among those detected during the sweep are radar waves from the speed measuring device, in the order in which they were detected during the sweep.

[0014] The inspection unit may include: a storage unit that stores as reception information a set of frequency information that identifies the frequency at which the radio wave reception was detected and the radio wave intensity level at which the radio wave reception was detected; an inspection target selection unit that sweeps up to the terminal frequency and then selects a predetermined number of the reception information in descending order of radio wave intensity level; and an inspection determination unit that, after sweeping up to the terminal frequency, fixes the frequency of the radio wave to be received based on the frequency information included in the reception information selected by the inspection target selection unit and determines whether it is a radar wave from a speed measuring device.

[0015] The receiving unit receives radio waves and converts them into a received signal, and the receiving detection unit may include a plurality of local oscillators, each outputting a signal of a predetermined frequency; a first-stage mixing unit that mixes the received signal with a signal of the frequency output by the first-stage local oscillator to output a first-stage intermediate frequency signal; a second or subsequent stage mixing unit that mixes a signal of the frequency output by the same-stage local oscillator with the previous stage intermediate frequency signal to output a next-stage intermediate frequency signal; and a sweep control unit that sweeps the frequency of the signal output by any of the second or subsequent local oscillators up to the termination frequency of a predetermined frequency band.

[0016] The receiving unit receives radio waves and converts them into a received signal, and the receiving detection unit may include: two local oscillator units, each outputting a signal of a predetermined frequency; a first-stage mixing unit, which mixes the received signal with the signal of the frequency output by the first-stage local oscillator unit to output a first-stage intermediate frequency signal; a second-stage mixing unit, which mixes the signal of the frequency output by the second-stage local oscillator unit with the first-stage intermediate frequency signal to output a next-stage intermediate frequency signal; and a sweep control unit, which sweeps the frequency of the signal output by the second-stage local oscillator unit up to the termination frequency of a predetermined frequency band.

[0017] The aforementioned inspection unit may be configured to fix the frequency to a predetermined number of radio waves with high radio wave intensity levels, and if radio wave reception is detected continuously for a predetermined period of time, it may be determined that the reception is of radar waves from the speed measuring device.

[0018] The frequencies of a predetermined number of radio waves with high radio wave intensity levels may be the frequencies at the peak of the radio wave intensity when the radio waves were received.

[0019] The radio waves detected during the sweep are undulation signals generated by low-frequency noise superimposed when radio waves are received while sweeping. The analysis unit may identify from the undulation signals the frequencies at which radio waves with a high signal strength level are generated when the low-frequency noise is not superimposed, and make a determination regarding the radio waves of those frequencies.

[0020] The aforementioned analysis unit may identify the zero signal level included in the undulation signal, excluding the range of white noise, and set the frequency shifted by a pre-stored offset value from that zero signal level to be the frequency of the radio wave with a high radio wave intensity level.

[0021] The receiving detection unit may include a detection unit that demodulates the intermediate frequency signal, and the reconnaissance unit may determine that the radar wave of the speed measuring device has been received if a certain number or more of specific frequency components are present in the output of the detection unit.

[0022] The aforementioned detailed analysis and determination unit may include a low-pass filter that passes the signal output by the detection unit, and if the number of occurrences of waveform periods corresponding to a specific frequency component is greater than or equal to a certain amount in the signal that has passed through the low-pass filter, it may be determined that the signal is a reception of the radar wave from the speed measuring device.

[0023] The aforementioned detailed analysis and determination unit may fix the frequency to the zero point or its vicinity of the waveform that appears when the radio wave reception is detected.

[0024] When the waveform when detecting the radio wave reception is an S-shaped waveform that once drops below the zero point and then rises toward the peak, the zero point is the zero point at a position where the frequency is lower than at the peak. When the waveform when detecting the radio wave reception is an N-shaped waveform that rises toward the peak and then drops below the zero point, the zero point may be the zero point at a position where the frequency is higher than at the peak.

[0025] The scrutiny determination unit may determine that it is the reception of the radar wave of the speed measurement device when there are a certain number or more of the specific frequency components and they are more than other frequency components.

[0026] When the frequency of the radio wave detected by the reception detection unit is within a specific range, the scrutiny unit may determine that it is the reception of the radar wave of the speed measurement device even if the number of specific frequency components in the output of the detection unit is less than a certain number, as long as radio wave reception is continuously detected for a predetermined time.

[0027] The scrutiny unit fixes the frequency to a predetermined number of radio waves with a high radio wave intensity level, continuously detects radio wave reception for a predetermined time, the frequency of the radio wave detected by the reception detection unit is within a specific range, and further, when the radio wave detected by the reception detection unit is an unmodulated wave, it may determine that it is the reception of the radar wave of the speed measurement device.

[0028] It includes a notification unit that notifies information. The scrutiny unit fixes the frequency to a predetermined number of radio waves with a high radio wave intensity level, continuously detects radio wave reception for a predetermined time, determines whether the frequency of the radio wave detected by the reception detection unit is within a specific range, and determines whether the radio wave detected by the reception detection unit is an unmodulated wave. The notification unit determines the information of radio wave detection that does not specify that it is the reception of the radar wave of the speed measurement device when the result of the scrutiny unit is that radio wave reception is continuously detected for a predetermined time, but the frequency of the radio wave detected by the reception detection unit is not within the specific range, and the radio wave detected by the reception detection unit is an unmodulated wave.

[0029] The system may be equipped with a notification unit for broadcasting information, wherein the inspection unit fixes the frequency to a predetermined number of radio waves with high radio wave intensity levels, detects radio wave reception for a predetermined period of time, determines whether the frequency of the radio wave detected by the reception detection unit is within a specific range, determines whether the radio wave detected by the reception detection unit is an unmodulated wave, and the notification unit may broadcast information indicating that the reception is of the radar wave of the speed measuring device if the result of the inspection unit is that radio wave reception is detected for a predetermined period of time but the frequency of the radio wave detected by the reception detection unit is not within a specific range, and if the radio wave detected by the reception detection unit is not an unmodulated wave.

[0030] The system may be equipped with a notification unit for broadcasting information, wherein the inspection unit fixes the frequency to a predetermined number of radio waves with high radio wave intensity levels, detects radio wave reception for a predetermined period of time, determines whether the frequency of the radio wave detected by the reception detection unit is within a specific range, determines whether the radio wave detected by the reception detection unit is an unmodulated wave, and if the result of the inspection unit is that radio wave reception has been detected for a predetermined period of time, the notification unit may broadcast information indicating that it is a reception of radar waves from the speed measuring device, while specifying the type of speed measuring device, depending on whether the frequency of the radio wave detected by the reception detection unit is within a specific range and whether the radio wave detected by the reception detection unit is an unmodulated wave.

[0031] The first-stage local oscillator may be configured to alternately change and output signals from different bands each time the sweep is repeated.

[0032] The first-stage local oscillator may, when the analysis unit determines that it has received a radar wave from the speed measuring device, output a signal without changing the band during the next sweep.

[0033] The system may also be equipped with a notification unit that notifies information when it is determined that the radar wave of the speed measuring device has been received.

[0034] The notification unit may also notify information when it determines a predetermined number of times that the radar waves of the speed measuring device have been received during a series of sweeps.

[0035] Furthermore, in order to achieve the above objectives, the detector according to the embodiment of the present invention is a detector installed in a vehicle that detects radar waves from a speed measuring device, and comprises: a receiving unit including an antenna; a detection unit which generates an intermediate frequency signal while sweeping a predetermined frequency range up to a terminal frequency, and the detection unit demodulates the intermediate frequency signal to detect radio wave reception; a refinement unit which determines whether the radar waves from the speed measuring device have been received after the receiving detection unit has swept up to the terminal frequency; and an input unit which accepts the user's selection of the strength of false alarm suppression, wherein the refinement unit determines whether the radar waves from the speed measuring device have been received by limiting it to a predetermined number of radio waves with high radio wave intensity levels among the radio waves detected during the sweep, and stores as reception information a set of frequency information that identifies the frequency at which the radio wave reception was detected and the radio wave intensity level at which the radio wave reception was detected; and a refinement target which selects a predetermined number of the reception information in descending order of radio wave intensity levels after sweeping up to the terminal frequency. The system includes a selection unit and a refinement determination unit that sweeps up to the terminal frequency, fixes the frequency of the received radio wave based on the frequency information included in the received information selected by the refinement target selection unit, and determines whether it is the reception of a radar wave from a speed measuring device. If the input unit accepts a selection of weak false alarm suppression, the refinement determination unit fixes the frequency of the received radio wave to a frequency based on the frequency information included in the received information selected by the refinement target selection unit, and determines that it is the reception of a radar wave from a speed measuring device if the radio wave reception is detected for a predetermined time. If the input unit accepts a selection of strong false alarm suppression, the refinement determination unit has a low-pass filter that passes the signal output by the detection unit, fixes the frequency to the zero point or near the zero point of the waveform that appears when radio wave reception is detected based on the received information selected by the refinement target selection unit, and determines that it is the reception of a radar wave from a speed measuring device if the number of occurrences of waveform periods corresponding to a specific frequency component is greater than or equal to a certain amount after passing through the low-pass filter. [Effects of the Invention]

[0036] According to the present invention, even if the number of radio wave detections during a sweep increases, the sweep cycle time will not be prolonged, the start of the next sweep will not be delayed, and the opportunities for the speed measuring device to receive radar waves can be increased. [Brief explanation of the drawing]

[0037] [Figure 1] This is a perspective view showing the side of the detector facing outwards from the vehicle. [Figure 2] This is a perspective view showing the side of the detector facing into the vehicle's interior. [Figure 3] This is a block diagram showing the internal configuration of the detector. [Figure 4] This is a block diagram showing the configuration of a radio wave receiving system according to the first embodiment. [Figure 5] This is a block diagram showing the configuration of the control unit according to the first embodiment. [Figure 6] This is a flowchart showing an example of the operation of the detector according to the first embodiment. [Figure 7] This is a schematic diagram illustrating the sweep operation of the detector's radio wave reception mode. [Figure 8] This is a schematic diagram illustrating the memory operation of received information during a sweep in the radio wave reception mode of the detector. [Figure 9] This is a schematic diagram showing the selection process for received information in the scrutiny mode. [Figure 10] This is a schematic diagram illustrating the operation of the detector's inspection function. [Figure 11] The differences in operation between the old and new radio wave detection systems are shown; (a) is a schematic diagram showing the conventional operation, and (b) shows the operation of this embodiment. [Figure 12] This is a schematic diagram showing the details of the demodulated signal output by the detection unit. [Figure 13] This is a block diagram showing the configuration of the control unit according to the second embodiment. [Figure 14] This flowchart shows the operation of the scrutiny mode according to the second embodiment. [Figure 15] This graph shows the waveform of the demodulated signal obtained by passing a modulated wave through a low-pass filter. [Figure 16] This is a schematic diagram showing the voltage levels corresponding to the demodulated signal being examined. [Figure 17] This is a concrete example of the waveform of a demodulated signal obtained by passing a modulated wave through a low-pass filter. [Figure 18] This is an enlarged graph showing the waveform of the demodulated signal obtained by passing the modulated wave through a low-pass filter. [Figure 19] This is an enlarged graph showing the area around the zero point of the demodulated signal obtained by passing a modulated wave through a low-pass filter. [Figure 20] This flowchart shows the operation of the detailed examination mode according to a modified example of the second embodiment. [Figure 21] This is a block diagram showing the internal configuration of the detector according to the third embodiment. [Figure 22] This flowchart shows the first half of the operation of the scrutiny mode according to the third embodiment. [Figure 23] This flowchart shows the latter half of the operation of the scrutiny mode according to the third embodiment. [Figure 24] This flowchart shows the operation of the detailed examination mode according to a modified example of the third embodiment. [Figure 25] This flowchart shows another example of operation 1 of the detailed examination mode according to a modified example of the third embodiment. [Figure 26] This flowchart shows another example of operation of the detailed examination mode according to a modified example of the third embodiment. [Figure 27] This flowchart shows another example of operation 3 of the detailed examination mode according to a modified example of the third embodiment. [Figure 28] This is a block diagram showing the configuration of the detector according to the fourth embodiment. [Figure 29] This is a flowchart showing the operation of the detector according to the fourth embodiment. [Figure 30] This is a flowchart illustrating the waveform inspection operation of the detector according to a modified example of the fourth embodiment. [Figure 31] This is a flowchart illustrating the operation of the detector according to the fifth embodiment. [Modes for carrying out the invention]

[0038] (First embodiment) (composition) A detector according to the first embodiment of the present invention will be described in detail with reference to the drawings. Figure 1 is a perspective view showing the side of the detector 1 facing out of the vehicle, and Figure 2 is a perspective view showing the side of the detector 1 facing inward into the vehicle.

[0039] Detector 1 is installed in vehicles such as automobiles, motorcycles, trucks, and buses. Detector 1 directly or indirectly provides information encouraging speed compliance in response to events that should prompt speed adherence. Detector 1 is typically installed on the dashboard and powered from the vehicle via an OBD-II connector or cigarette lighter socket. The dashboard is an example of a location where radar waves emitted by speed measuring devices can be easily received and information can be provided to the driver.

[0040] Speed ​​measuring devices include fixed and mobile devices that emit radar waves. Events that prompt speed compliance include when a vehicle reaches a predetermined distance from a speed measuring device whose location is known, and when the vehicle receives radar waves emitted by the speed measuring device. The radar waves are, for example, K-band frequencies in the 24GHz band and are modulated microwaves such as frequency-modulated microwaves. The information that the detector 1 reports may include, for example, the presence of a speed measuring device, the type of speed measuring device, the reception and type of radar waves emitted by the speed measuring device, or a warning to comply with the speed limit, or a combination of these.

[0041] As shown in Figures 1 and 2, the detector 1 is equipped with a screen 14, a speaker 15, and a lamp 16 on the outer surface of the housing 10. The screen 14 is a liquid crystal display or an organic EL display, etc., and is located on the front 12 of the detector 1, displaying notification information in a visually appealing format such as characters, pictures, and symbols. The speaker 15 outputs the notification information as sound. The lamp 16 indicates the notification information through regular illumination such as color, flashing, and lighting intervals. The front 12 faces inward and is visible to the driver, while the rear 11 faces outward through the windshield.

[0042] The rear surface 11 of the detector 1 is a reception area 13. The radio wave receiving system 2 and the positioning signal receiving system 3 are housed inside the housing 10 on the rear surface 11. The radio wave receiving system 2 has a double superheterodyne receiving circuit and receives and detects radar waves emitted by the speed measuring device. The positioning signal receiving system 3 has an antenna, demodulator, and processor capable of receiving radio signals from positioning satellites, and receives and demodulates GNSS (Global Navigation Satellite System) positioning signals to calculate the vehicle's position, which consists of the latitude and longitude of the current location.

[0043] Figure 3 is a block diagram showing the internal configuration of the detector 1. As shown in Figure 3, the detector 1 further comprises a control unit 5 and a notification unit 6. The radio wave receiving system 2 and the positioning signal receiving system 3 input and output signals to the control unit 5. This control unit 5 is a so-called computer that includes a processor such as a CPU, DSP, GPU, FPGA, or microcontroller, storage for storing programs and data, and work memory.

[0044] The control unit 5 controls the radio wave receiving system 2 and determines whether radar waves from the speed measuring device have been received. The control unit 5 also determines the distance between the vehicle's position, output by the positioning signal receiving system 3, and speed measuring devices whose installation locations are known, as well as locations where speed measuring devices have been installed in the past (hereinafter collectively referred to as registered speed measuring devices). The control unit 5 then causes the notification unit 6 to notify information according to the determination result. The notification unit 6 consists of a screen 14, a speaker 15, a lamp 16, or a combination thereof, located on the outer surface of the housing 10.

[0045] Figure 4 is a block diagram showing the detailed configuration of the radio wave receiving system 2 of the detector 1. The radio wave receiving system 2 comprises a receiving unit 21 and a receiving detection unit 22. The receiving unit 21 includes an antenna that receives at least the K-band frequency range and outputs a received signal RF, a bandpass filter that removes unwanted frequency components from the received signal RF, and a low-noise amplifier that amplifies the received signal RF. This receiving unit 21 may be separated from the detector 1 and mounted in a separate enclosure in the vehicle.

[0046] The reception detection unit 22 generates an intermediate frequency signal by sweeping the frequency of the local oscillator signal that is mixed with the received RF signal, and detects radio wave reception based on the intermediate frequency signal. This reception detection unit 22 includes a first-stage local oscillator unit 23, a first-stage mixing unit 24, a second-stage local oscillator unit 25, a second-stage mixing unit 26, a sweep control unit 27, and a detection unit 28.

[0047] The first stage mixing unit 24 and the second stage mixing unit 26 are active mixers that perform frequency conversion using transistors as a base, for example. The first stage mixing unit 24 converts the received signal RF input from the receiving unit 21 into the first stage intermediate frequency signal IFf. The second stage mixing unit 26 converts the first stage intermediate frequency signal IFf input from the first stage mixing unit 24 into the second stage intermediate frequency signal IFs.

[0048] The first stage mixer 24 receives the first stage local oscillator signal LFf from the first stage local oscillator 23. The first stage mixer 24 outputs the first stage intermediate frequency signal IFf as a result of the difference between the frequency of the received signal RF and the first stage local oscillator signal LFf. The second stage mixer 26 receives the second stage local oscillator signal LFs from the second stage local oscillator 25. The second stage mixer 26 outputs the second stage intermediate frequency signal IFs as a result of the difference between the frequency of the first stage intermediate frequency signal IFf and the second stage local oscillator signal LFs.

[0049] Furthermore, the first stage mixing unit 24 may be equipped with a low-pass filter and an amplifier in the subsequent stage. Alternatively, a low-noise amplifier that amplifies the received signal RF may be provided instead of the receiving unit. This first stage mixing unit 24 cuts out the received signal RF, the first stage local oscillator signal LFf, and the signal resulting from the sum of the frequencies of the received signal RF and the first stage local oscillator signal LFf from the mixing result. The first stage mixing unit 24 then amplifies and outputs only the first stage intermediate frequency signal IFf.

[0050] Furthermore, the second stage mixing unit 26 may also include a low-pass filter and an amplifier in the subsequent stage. This second stage mixing unit 26 cuts out the intermediate frequency signal IFf from the first stage, the local oscillator signal LFs from the second stage, and the signal resulting from the sum of the frequencies of the intermediate frequency signal IFf from the first stage and the local oscillator signal LFs from the second stage from the mixing result. The second stage mixing unit 26 then amplifies and outputs only the intermediate frequency signal IFs from the second stage.

[0051] The first-stage local oscillator signal LFf has a predetermined, fixed frequency. On the other hand, the frequency of the second-stage local oscillator signal LFs varies depending on the mode. In radio wave reception mode, the frequency of the second-stage local oscillator signal LFs changes by sweeping a predetermined frequency range fb from the start frequency fs at one end to the end frequency fe at the other end. In refinement mode, the frequency of the second-stage local oscillator signal LFs is fixed to one of the frequencies within the predetermined frequency range fb.

[0052] This second-stage local oscillator 25 is, for example, a voltage-controlled oscillator (VCO). This second-stage local oscillator 25 generates a second-stage local oscillator signal LFs in response to the sweep voltage signal SV input from the sweep control unit 27. The sweep control unit 27 inputs the sweep voltage signal SV to the second-stage local oscillator 25 so that the second-stage local oscillator signal LFs sweeps a predetermined frequency range fb from the start frequency fs at one end to the end frequency fe at the other end.

[0053] In other words, the sweep control unit 27 continuously changes the sweep voltage signal SV from, for example, a starting sweep voltage signal SVs of 0V corresponding to the starting frequency fs of a predetermined frequency range fb, to, for example, a ending sweep voltage signal SVe of 3.3V corresponding to the ending frequency fe of a predetermined frequency range fb.

[0054] This sweep control unit 27 is controlled by the control unit 5 of the detector 1. When the sweep is completed up to the termination frequency fe, the sweep control unit 27 inputs a sweep completion notification signal Ce to the control unit 5. The sweep control unit 27 receives a sweep start control signal Cs from the control unit 5 and starts controlling the sweep. When the control unit 5 inputs a specific frequency continuation control signal Cc indicating a specific frequency, the sweep control unit 27 continues to input a constant voltage signal CV to the second stage local oscillator unit 25 in order to continue the second stage local oscillator signal LFs indicated by the specific frequency continuation control signal Cc from the control unit 5.

[0055] Furthermore, the method for specifying a specific frequency using the specific frequency continuation control signal Cc may be any of the following: information indicating the frequency of the received radio wave, information indicating the second-stage local oscillator signal LFs, or information indicating the constant voltage signal CV output by the sweep control unit 27. If the specific frequency continuation control signal Cc includes information indicating the frequency of the received radio wave or information indicating the second-stage local oscillator signal LFs, the sweep control unit 27 calculates the constant voltage signal CV.

[0056] The detection unit 28 amplifies and detects the second-stage intermediate frequency signal IFs, and outputs a detection signal Sc expressed as a voltage. The detection signal Sc from the detection unit 28 is AD converted and input to the control unit 5. If no radio waves in the K-band frequency range are received, the detection signal Sc is white noise Sn. On the other hand, if a radio wave of a predetermined frequency within the K-band frequency range is received, the detection signal Sc is a demodulated signal Sd with a voltage level above a certain level. If the sweep is not stopped, the demodulated signal Sd exhibits a pulse waveform in which the minimum and maximum values ​​of the output voltage appear around the center frequency, due to the S-curve and N-curve characteristics that appear in the relationship between frequency and voltage.

[0057] Here, the S-shaped curve characteristic shows an S-shaped waveform that first drops below zero, passes through a local minimum, and then rises towards a local maximum. The N-shaped curve characteristic shows an N-shaped waveform that rises towards a local maximum, then drops below zero, and reaches a local minimum.

[0058] Figure 5 is a block diagram showing the detailed configuration of the control unit 5 of the detector 1. The control unit 5 comprises a detailing unit 51 and a notification control unit 52. The detailing unit 51 determines whether a predetermined number of radio waves detected by the reception detection unit 22 while it is sweeping are radar waves from a speed measuring device, in order of decreasing radio wave intensity level Ds.

[0059] This inspection unit 51 includes a reception determination unit 53, a reception information storage unit 54, an inspection target selection unit 55, and an inspection determination unit 56. The inspection determination unit 56 also includes a tuning control unit 57 and a signal monitoring unit 58.

[0060] The reception determination unit 53 detects the demodulated K-band signal Sd from the detected signal Sc detected by the detection unit 28 of the reception detection unit 22. The reception determination unit 53 has a threshold value higher than the white noise Sn stored in its memory. The reception determination unit 53 compares the detected signal Sc with the threshold value. If the detected signal Sc exceeds the threshold value, the detected signal Sc is the demodulated signal Sd.

[0061] When the reception information storage unit 54 detects the demodulated signal Sd from the reception determination unit 53, it generates and stores reception information Dr. Reception information Dr is added to and stored each time the demodulated signal Sd is detected during a sweep. The group of reception information Dr added during a sweep is initialized during the next sweep. Reception information Dr includes frequency information Df and signal strength level Ds as a set. Frequency information Df directly or indirectly identifies the frequency of the received radio wave. Signal strength level Ds identifies the strength of the received radio wave by classifying it into levels.

[0062] Frequency information Df is, for example, the frequency of the received radio wave when the demodulated signal Sd is generated. Alternatively, frequency information Df is the frequency of the second-stage local oscillator signal LFs when the radio wave is received. Alternatively, frequency information Df is the sweep voltage signal SV that causes this second-stage local oscillator signal LFs to output.

[0063] The radio wave strength level Ds may be obtained by dividing the RSSI value (Received Signal Strength Indicator) into multiple levels. Alternatively, the radio wave strength level Ds may be obtained by dividing the peak-to-peak value of the demodulated signal Sd into multiple levels. Alternatively, the radio wave strength level Ds may be obtained by dividing the difference from the peak to the zero point of the demodulated signal Sd into multiple levels. The RSSI value may be obtained from the received signal strength indicator of the detection unit 28.

[0064] The refinement target selection unit 55 selects the radio waves to be refined. This refinement target selection unit 55 begins selection after receiving a sweep completion notification signal Ce from the sweep control unit 27, which indicates the end of the sweep. The refinement targets are selected from the received information Dr. The refinement target selection unit 55 picks up a predetermined number of received information Dr in descending order of radio wave intensity level Ds. Here, there is a characteristic that the demodulated signal Sd appears twice for one radio wave reception. Therefore, the predetermined number is preferably at least four or more, but the fewest possible number is advantageous, and most preferably four.

[0065] The refinement and determination unit 56 performs a refinement to determine whether the reception is of radar waves from the speed measuring device, by referring to the reception information Dr selected by the refinement target selection unit 55. Of the refinement and determination unit 56, the tuning control unit 57 inputs a specific frequency continuation control signal Cc to the sweep control unit 27. The specific frequency continuation control signal Cc directly or indirectly identifies the frequency of the radio wave to be received and instructs the continuation of reception of radio waves at this frequency. The frequency of the radio wave to be received is identified by the frequency information Df included in the reception information Dr. That is, the tuning control unit 57 generates the specific frequency continuation control signal Cc by referring to the frequency information Df included in the reception information Dr.

[0066] The sweep control unit 27 continuously inputs a constant voltage signal CV corresponding to the specific frequency continuation control signal Cc to the second stage local oscillator unit 25. The second stage local oscillator unit 25 continuously inputs the second stage local oscillator signal LFs, which is specified by the frequency information Df, to the second stage mixer unit 26. Therefore, the specific frequency continuation control signal Cc can be any of the following: the frequency of the received radio wave when the demodulated signal Sd is generated, the frequency of the second stage local oscillator signal LFs when this radio wave is received, or the sweep voltage signal SV that causes this second stage local oscillator signal LFs to be output.

[0067] Of the inspection and determination units 56, the signal monitoring unit 58 monitors the continuation of radio wave reception while continuously outputting a constant second-stage local oscillator signal LFs. That is, the signal monitoring unit 58 monitors the continuation of the demodulated signal Sd input by the detection unit 28. The predetermined time is, for example, 30 ms, according to the duration of the radio waves emitted by the speed measuring device. In other words, if the monitoring results show that the continuation of radio wave reception has reached the predetermined time, the received radio wave is the radio wave emitted by the speed measuring device.

[0068] The signal monitoring unit 58 stores a threshold value set to be less than the intensity of the demodulated signal Sd. The signal monitoring unit 58 also stores a predetermined time in advance. The signal monitoring unit 58 continuously compares the intensity of the demodulated signal Sd with the threshold value while timing the duration of the demodulated signal Sd. If the intensity of the demodulated signal Sd continues to exceed the threshold value until the predetermined duration is reached, the signal monitoring unit 58 determines that it is receiving radio waves emitted by the speed measuring device. When the notification control unit 52 determines that the signal monitoring unit 58 is receiving radar waves from the speed measuring device, it outputs information to the notification unit 6 to provide notification.

[0069] If the intensity of the demodulated signal Sd falls below a threshold, the refinement determination unit 56 performs a refinement using the remaining received information Dr selected by the refinement target selection unit 55. If it is not determined that all of the received information Dr selected by the refinement target selection unit 55 are radio waves emitted by the speed measuring device, the tuning control unit 57 inputs a sweep start control signal Cs to the sweep control unit 27 in order to start the next sweep.

[0070] Figure 6 is a flowchart illustrating an example of operation by the control unit 5. As shown in Figure 6, first the received information storage unit 54 initializes the received information Dr (step S101). Next, the tuning control unit 57 starts the sweep (step S102). In step S102, for example, the tuning control unit 57 inputs a sweep start control signal Cs to the sweep control unit 27.

[0071] When the sweep control unit 27 receives the sweep start control signal Cs, it sets the sweep voltage signal SV to the starting sweep voltage signal SVs and inputs it to the second stage local oscillator unit 25. The sweep control unit 27 inputs the sweep voltage signal SV while continuously and nonstop changing it from the starting sweep voltage signal SVs to the ending sweep voltage signal SVe. The second stage local oscillator unit 25 inputs the second stage local oscillator signal LFs to the second mixer 26 while continuously and nonstop changing it from the starting frequency fs corresponding to the starting sweep voltage signal SVs to the ending frequency fe corresponding to the ending sweep voltage signal SVe.

[0072] The received signal RF received by the receiving unit 21 is converted into the first-stage intermediate frequency signal IFf by the first-stage mixing unit 24. The first-stage intermediate frequency signal IFf is input to the second-stage mixing unit 26 and converted into the second-stage intermediate frequency signal IFs according to a sweep of a predetermined frequency range fb. The detection unit 28 detects the second-stage intermediate frequency signal IFs and inputs the detected signal Sc to the control unit 5.

[0073] When the detection signal Sc is input, the reception determination unit 53 analyzes the detection signal Sc to determine whether it corresponds to the reception of radio waves (step S103). In step S103, for example, the reception determination unit 53 determines whether the detection signal Sc contains a demodulated signal Sd. The reception determination unit 53 detects the demodulated signal Sd by comparing the detection signal Sc with a threshold. If it corresponds to radio wave reception (step S103, Yes), the reception information storage unit 54 generates and stores reception information Dr related to the received radio waves (step S104).

[0074] The reception information storage unit 54 stores the frequency information Df and signal strength level Ds of the demodulated signal Sd as a set of reception information Dr. The reception information storage unit 54 stores the sweep voltage signal SV when the demodulated signal Sd is received as frequency information Df. Alternatively, the reception information storage unit 54 calculates the frequency of the second local oscillator signal LFs from this sweep voltage signal SV and stores it as frequency information Df. Alternatively, the reception information storage unit 54 calculates the frequency of the received signal RF from this sweep voltage signal SV and stores it as frequency information Df.

[0075] The received information storage unit 54 acquires the RSSI value when the demodulated signal Sd is received, divides it into predetermined levels, and stores it as the radio wave intensity level Ds. Alternatively, the received information storage unit 54 acquires the peak-to-peak value of the demodulated signal Sd, divides it into predetermined levels, and stores it as the radio wave intensity level Ds. Alternatively, the received information storage unit 54 acquires the difference from the peak to the zero level of the demodulated signal Sd, divides it into predetermined levels, and stores it as the radio wave intensity level Ds.

[0076] If the sweep is in progress within the predetermined frequency range fb (step S105, No), the sweep is not stopped, and the reception determination unit 53 repeatedly determines whether radio waves have been received and adds reception information Dr if radio waves have been received (steps S103 to S105). When the sweep is completed up to the termination frequency fe of the predetermined frequency range fb (step S105, Yes), the refinement determination unit 56 switches to refinement mode (steps S106 to S105). For example, a sweep completion notification signal Ce is input to the control unit 5 from the sweep control unit 27. This sweep completion notification signal Ce triggers the refinement determination unit 56 to switch to refinement mode.

[0077] When one sweep is completed up to the termination frequency fe of the predetermined frequency range fb (step S105, Yes), the selection unit 55 selects a predetermined number of received information Drs from the group of received information Drs collected in one sweep, in descending order of radio wave intensity level Ds (step S106).

[0078] The tuning control unit 57 switches the received information Dr from the selected group of received information Dr in the order in which radio waves were received during the sweep, and fixes the frequency of the received radio wave in the frequency information Df included in the received information Dr (step S107). That is, the tuning control unit 57 inputs a specific frequency continuation control signal Cc to the sweep control unit 27, for example, which instructs the continuous output of a constant voltage signal CV corresponding to the frequency information Df.

[0079] While the frequency is fixed to this frequency information Df, the signal monitoring unit 58 monitors whether the demodulated signal Sd continues for a predetermined time (step S108). For example, the signal monitoring unit 58 compares the demodulated signal Sd input from the detection unit 28 with a threshold and continues to determine whether the demodulated signal Sd continues to exceed the threshold for a predetermined time.

[0080] If the demodulated signal Sd does not continue for a predetermined time (step S108, No), and if there are any unchecked received information Drs among the received information Drs selected by the inspection target selection unit 55 (step S109, Yes), the frequency is fixed to the frequency of the remaining received information Drs (step S107). The signal monitoring unit 58 then monitors whether the demodulated signal Sd continues for a predetermined time (step S108). If none of the demodulated signals Sd continue for the predetermined time and the inspection of all received information Drs is completed (step S109, No), the process returns to step S101, the received information Drs are initialized, and the sweep for the next cycle is started (steps S102~).

[0081] On the other hand, if the demodulated signal Sd continues for a predetermined time or longer (step S108, Yes), the notification control unit 52 causes the notification unit 6 to notify (step S110). That is, the detector 1, after careful examination, determines that it has received radar waves emitted by the speed measuring device and notifies the information. Then, returning to step S101, the received information Dr is initialized and the sweep for the next cycle is started (steps S102~).

[0082] Figure 7 is a schematic diagram showing the sweep operation of the radio wave reception mode of this detector 1. As shown in Figure 7(a), in the radio wave reception mode, the tuning control unit 57 inputs the sweep voltage signal SV to the second stage local oscillator unit 25 while sweeping from the start sweep voltage signal SVs to the end sweep voltage signal SVe without sweep stopping.

[0083] As shown in Figure 7(b), the second-stage local oscillator 25, which receives the sweep voltage signal SV, inputs the frequency of the second-stage local oscillator signal LFs to the second-stage mixer 26 in the radio wave reception mode, sweeping a predetermined frequency range fb from the start frequency fs to the end frequency fe without sweeping.

[0084] As shown in Figure 7(c), the detected signal Sc becomes white noise Sn near the zero point when no radio waves are received. When radio waves are received, the detected signal Sc becomes the demodulated signal Sd. The demodulated signal Sd has an S-curve characteristic in the relationship between frequency and voltage, and due to this S-curve characteristic, the minimum and maximum values ​​of the output voltage appear around the center frequency, resulting in a pulse waveform.

[0085] Figure 8 is a schematic diagram showing the memory operation of reception information Dr during sweep in the radio wave reception mode of the detector 1. As shown in Figure 8, during sweep in radio wave reception mode, the reception determination unit 53 determines whether a demodulated signal Sd is being received by using a threshold value. Even if it is a demodulated signal Sd, the sweep is not stopped, and the reception information storage unit 54 combines the frequency information Df that identifies the frequency of the demodulated signal Sd and the radio wave intensity level Ds of the demodulated signal Sd into a single reception information Dr. The reception information storage unit 54 then stores the reception information Dr each time it obtains a demodulated signal Sd during a single sweep.

[0086] For example, as shown in Figure 8, during one sweep, the demodulated signals Sd1 to Sd7 are detected seven times. The sweep voltage signal CV when demodulated signal Sd1 is detected is acquired as frequency information Df1. In addition, the peak value of demodulated signal Sd1 is acquired as the signal strength level Ds1.

[0087] The sweep voltage signal CV obtained when the demodulated signal Sd2 is detected is acquired as frequency information Df2. The peak value of the demodulated signal Sd2 is also acquired as the signal strength level Ds2. The sweep voltage signal CV obtained when the demodulated signal Sd3 is detected is acquired as frequency information Df3. The peak value of the demodulated signal Sd3 is also acquired as the signal strength level Ds3. Similarly, the sweep voltage signals CV obtained when the demodulated signals Sd1 to Sd7 are detected are acquired as frequency information Df1 to Df7. The peak values ​​of the demodulated signals Sd1 to Sd7 are also acquired as signal strength levels Ds1 to Ds7.

[0088] Figure 9 is a schematic diagram showing the selection of received information Dr in the refinement mode. As shown in Figure 9, when the sweep reaches the termination frequency fe of a predetermined frequency range fb, the system switches from radio wave reception mode to refinement mode. In radio wave reception mode, when seven demodulated signals Sd1 to Sd8 are detected during the sweep, frequency information Df1 to Df7 is acquired for all demodulated signals Sd1 to Sd7, and radio wave strength levels Ds1 to Ds7 are also acquired, and received information Dr1 to Dr7 is stored.

[0089] The selection unit 55 selects a predetermined number of received information Drs, for example, four. The selection criteria are in descending order of radio wave intensity level Ds. However, the review determination unit 56 reviews the selected received information Drs in the order in which radio waves were received during the sweep. The predetermined number is the maximum value. If the number of received information Drs is less than the predetermined number, all received information Drs are reviewed in the order in which radio waves were received during the sweep.

[0090] Figure 10 is a schematic diagram showing the operation of the detector 1 for detailed analysis. As shown in Figure 10, the receiver information Dr of the detected demodulated signal Sd is stored while sweeping a predetermined frequency range fb. When the radio wave reception mode ends by sweeping to the termination frequency fe, the system switches from radio wave reception mode to detailed analysis mode. In detailed analysis mode, a predetermined number of receiver information Dr1, Dr3, Dr6, and Dr7 with high radio wave intensity levels Ds are selected from the seven stored receiver information Dr1 to Dr7.

[0091] As shown in Figure 10, after a sweep of the predetermined frequency range fb is completed, the radar waves of the speed measuring device are sequentially identified for the radio waves at the frequencies indicated by the selected received information Dr1, Dr3, Dr6, and Dr7. By selecting the information in the order it was received during the sweep, the detection signal Sc in the refinement mode becomes a step-like structure with a sequentially increasing voltage. As a result, the signal amplitude when the next received information Dr is selected becomes smaller, and the detection signal Sc becomes more stable. On the other hand, if the refinement mode is executed sequentially starting with the received information Dr with the highest radio wave intensity level Ds, the possibility of detecting the radar waves of the speed measuring device earlier increases, and the refinement mode may be shortened.

[0092] Figure 11 shows the difference in operation between the old and new radar detection systems, where (a) is a schematic diagram showing the conventional operation and (b) shows the operation of this embodiment. As shown in Figures 11(a) and (b), the radar wave irradiation of the speed measuring device starts at time Ts and ends at time Te. In both the conventional detector shown in Figure 11(a) and the detector 1 of this embodiment shown in Figure 11(b), the sweep S1 is assumed to have changed before time Ts by passing through a sweep voltage signal SVo suitable for receiving the radar wave of the speed measuring device.

[0093] As shown in Figure 11(a), conventionally, when demodulated signals Sd1 to Sd7 were detected during sweep S1, a sweep stop was performed to temporarily pause sweep S1 each time a demodulated signal Sd1 to Sd7 was detected, allowing for verification that it was a radar wave from a speed measuring device.

[0094] Therefore, if the number of radio wave detections during a single sweep increases and each radio wave does not originate from the speed measuring device, the cycle time CT from the start of sweep S1 to the start of the next sweep S2 becomes longer. A longer cycle time CT increases the likelihood that the irradiation time Ro of the speed measuring device's radar wave will have elapsed before the time Ts reaches the sweep voltage signal SVO in the next sweep S2. In other words, the timing of receiving the speed measuring device's radar wave will not match in both sweep S1 and sweep S2, reducing the chances of receiving the speed measuring device's radar wave.

[0095] On the other hand, as shown in Figure 11(b), in the detector 1 of this embodiment, even if demodulated signals Sd1 to Sd7 are detected during sweep S1, sweep S1 is completed to the end. Then, after sweep S1, a predetermined number of demodulated signals Sd1 to Sd7 that have a relatively high probability of being radar waves from a speed measuring device are selected and examined.

[0096] Therefore, even if a large number of radio waves are received during sweep S1, the cycle time CT from the start of sweep S1 to the start of the next sweep S2 remains constant and short. Consequently, the likelihood of the radar wave irradiation time Ro of the speed measuring device matching the arrival time Ts of the sweep voltage signal SVo in sweep S2 increases. Therefore, this detector 1 has an increased chance of receiving the radar wave of the speed measuring device.

[0097] For example, if there are many vending machines nearby and many vehicles with an auto-cruise function that detects the distance to the vehicle in front using radar are nearby, radio wave detection may occur up to 60 times during one sweep S1. If the time for one check is 30ms and no radar waves from the vehicle measurement device are detected, 1.8 seconds will be required just for the check before the next sweep S2 can begin. On the other hand, if the number of checks performed by the detector 1 of this embodiment is limited to, for example, four, the check time is 0.12 seconds, and the next sweep S2 can be started quickly.

[0098] As described above, the detector 1 of this embodiment includes a receiving unit 21, a receiving detection unit 22, and a refining unit 51. The refining unit 51 limits the frequencies of a predetermined number of radio waves detected during the sweep to those with the highest radio wave intensity level Ds, and determines whether they are radar waves from a speed measuring device.

[0099] This ensures that even if a large number of radio waves are detected during the previous sweep, the start of the next sweep is not delayed, improving the chances of the speed measuring device receiving radar waves.

[0100] To perform a detailed examination limited to a predetermined number of radio wave frequencies with high radio wave intensity levels Ds, the examination unit 51 includes a reception information storage unit 54, an examination target selection unit 55, and an examination determination unit 56. The reception information storage unit 54 stores reception information Dr, which is a set of frequency information Df that identifies the frequency at which radio wave reception was detected and the radio wave intensity level Ds at the time of detection. The examination target selection unit 55 sweeps up to the terminal frequency fe and then selects a predetermined number of reception information Dr in descending order of radio wave intensity levels Ds. The examination determination unit 56 sweeps up to the terminal frequency fe and then refers to the reception information Dr selected by the examination target selection unit 55. The examination determination unit 56 then fixes the frequency of the radio wave to be received based on the frequency information Df included in the reception information Dr and determines whether it is a radar wave from a speed measuring device.

[0101] In this way, even if radio waves are received during a sweep, the sweep is not stopped for further analysis. Instead, the sweep is completed, and the received radio waves are stored as reception information Dr. This allows for analysis to be limited to a predetermined number of radio wave frequencies in descending order of radio wave intensity level Ds. Furthermore, even with methods other than this, limiting the analysis to a predetermined number of radio wave frequencies in descending order of radio wave intensity level Ds prevents delays in the start of the next sweep, even if many radio waves are detected during the previous sweep, thereby improving the opportunity to receive radar waves from the speed measuring device.

[0102] In this embodiment, a double superheterodyne system was used as an example for explanation, but the system is not limited to this. For example, a third-stage local oscillator and mixer may be included to detect the intermediate frequency signal of the third stage. That is, the receiving detection unit 22 may be equipped with three or more stages of local oscillators and mixers.

[0103] Furthermore, in this detector 1, if it is determined that the radar waves of the speed measuring device have been received in one examination mode, the notification unit 6 is instructed to notify the information. However, it is not limited to this, and the notification unit 6 may only be instructed to notify the information when it is determined that the radar waves of the speed measuring device have been received consecutively over multiple cycles. In other words, the accuracy of false alarm suppression may be improved as the opportunities to receive radar waves from the speed measuring device are increased.

[0104] Furthermore, the notification unit 6 may be configured to notify information if it is determined that the radar waves of the speed measuring device have been received for a predetermined number of cycles or more within a series of consecutive cycles. This also improves the accuracy of suppressing false alarms.

[0105] (Modified version of the first embodiment) Figure 12 is a schematic diagram showing the details of the demodulated signal Sd output by the detection unit 28. During sweeping in radio wave reception mode, low-frequency noise SL, whose magnitude corresponds to the strength of the radio wave, is superimposed on the detected signal Sc. Therefore, a swirling signal Sw, in which low-frequency noise SL is superimposed on the detected signal Sc during sweeping, may appear prominently. The frequency at which the peak of the swirling signal Sw appears may differ from the frequency at which the peak of the demodulated signal Sd, obtained by fixing the frequency without sweeping, appears.

[0106] Therefore, when frequency information Df is obtained from this undulation signal Sw to be included in the received information Dr, there may be cases where the frequency is fixed to a frequency outside the peak and the system monitors whether the demodulated signal Sd continues for a predetermined time. In this case, because the frequency is fixed to a frequency outside the peak, there is a risk that the demodulated signal Sd will fall below the threshold of the signal monitoring unit 58 without continuing for the predetermined time. In this case, the notification accuracy can be further improved.

[0107] In other words, the received information storage unit 54 in this modified version corrects the undulating signal Sw to a non-undulating detected signal Sc before acquiring frequency information Df. Here, the undulating signal Sw is independent of the low-frequency noise SL, and excluding the white noise range, the position of the zero level of the signal in the demodulated signal Sd is the same as that of the detected signal Sc. Therefore, the received information storage unit 54 identifies the position of the zero level of the signal using a correlation filter.

[0108] The correlation filter obtains a predetermined number of voltage values ​​before and after the target voltage from the detected signal Sc, including the voltage to be corrected. The correlation filter then calculates the average value of the predetermined number of voltage values ​​before and after the target voltage. Next, the correlation filter calculates the sum of the sums obtained by subtracting the average value from each voltage value that was used to calculate the average. The correlation filter then subtracts the sum of the sums obtained by

[0109] The received information storage unit 54 searches for the absolute peak among the difference values ​​after the correlation filter has been applied. The position of this absolute peak is the position of the zero level signal in the demodulated signal Sd.

[0110] The received information storage unit 54 stores the offset value in advance. The offset value can be measured and stored in advance from the undulation signal Sw and the demodulated signal Sd when the frequency is fixed. The received information storage unit 54 includes the position shifted by the offset value from the position of the zero level of the signal in the demodulated signal Sd, i.e., the position of the absolute value peak obtained by applying the correlation filter, as frequency information Df in the received information Dr.

[0111] Furthermore, for demodulated signals Sd that exhibit an S-shaped curve characteristic, where the signal drops once before rising, the offset value is added over time. For demodulated signals Sd that exhibit an N-shaped curve characteristic, where the signal rises once before falling, the offset value is subtracted over time.

[0112] (Second embodiment) A detector 1 according to a second embodiment of the present invention will be described in detail with reference to the drawings. In the second embodiment, components that are the same as those in the first embodiment or have the same functions are denoted by the same reference numerals and their detailed descriptions are omitted.

[0113] Figure 13 is a block diagram showing the configuration of the control unit 5 included in the detector 1 of the second embodiment. The detector 1 of the first embodiment was equipped with a signal monitoring unit 58 that determined that the radio waves were radar waves from a speed measuring device when they were detected to continue for a predetermined time. In contrast, the detailed analysis and determination unit 56 of the second embodiment is equipped with a low-pass filter 59a and a signal waveform analysis unit 59b.

[0114] Figure 14 is a flowchart showing the operation of the refinement mode according to the second embodiment. As shown in Figure 14, the refinement target selection unit 55 selects a predetermined number of received information Dr (steps S101 to S106). The tuning control unit 57 sets the frequency of the radio wave to be received to the frequency information Df in the received information Dr (step S201), and then modulates the second stage local oscillator signal until the demodulated signal Sd reaches a voltage level at or near the zero point Sz (step S203, Yes) (step S202).

[0115] In steps S202 and S203, the tuning control unit 57 monitors the voltage level of the demodulated signal Sd. It generates an error signal between the voltage level of the demodulated signal Sd and the voltage level of the zero point Sz or its vicinity, and generates a specific frequency continuation control signal Cc that sets this error signal to zero, and inputs it to the sweep control unit 27.

[0116] When the demodulated signal Sd reaches a voltage level at or near the zero point Sz (step S203, Yes), the low-pass filter 59a cuts out high-frequency components from the demodulated signal Sd output by the detection unit 28 (step S204). The signal waveform analysis unit 59b measures the period of each waveform that appears in chronological order in the demodulated signal Sd that has passed through the low-pass filter 59a (step S205). Then, the signal waveform analysis unit 59b compiles the frequency distribution of each measured period (step S206).

[0117] Until the predetermined analysis time has elapsed (Step S207, Yes), the signal waveform analysis unit 59b continues to measure the period of each waveform and compile the frequency distribution. Once the predetermined analysis time has elapsed (Step S207, Yes), the signal waveform analysis unit 59b compares the frequency of a specific class in the frequency frequency distribution with a threshold value stored in advance (Step S208). If the frequency of a specific class is equal to or greater than the threshold value (Step S208, Yes), the notification control unit 52 causes the notification unit 6 to notify (Step S209). That is, the detector 1, after careful examination, determines that it has received radar waves emitted by the speed measuring device and notifies the information. Then, returning to Step S101, the received information Dr is initialized and the sweep for the next cycle is started (Steps S102~).

[0118] If the frequency of a specific class is below the threshold (Step S208, No), and there are still unexamined received information Drs among the received information Drs selected by the examination target selection unit 55 (Step S109, Yes), the frequency is fixed to that of the remaining received information Drs (Step S201). On the other hand, if the examination of all received information Drs is completed (Step S109, No), the process returns to Step S101 to initialize the received information Drs and start the sweep for the next cycle (Steps S102~).

[0119] Here, the K-band radar wave from the speed measuring device is modulated. Figure 15 shows the waveform of the demodulated signal Sd obtained by passing this modulated wave through the low-pass filter 59a. As shown in Figure 15, the modulated K-band radar wave emitted by the speed measuring device, when converted to the demodulated signal Sd after passing through the low-pass filter 59a, becomes a sine wave of a specific period. A specific class is selected corresponding to the period of the modulated K-band radar wave emitted by the speed measuring device.

[0120] Furthermore, the amplitude of this sine wave exceeds the high-level input voltage VIH and the low-level input voltage VIL during AD conversion. Therefore, the signal waveform analysis unit 59b uses interrupts to measure the time during which the high-level input voltage VIH, the low-level input voltage VIL, or both are exceeded, instead of performing waveform measurement. As a result, calculation processing such as FFT processing is omitted in the control unit 5, shortening the analysis time. This also shortens the sweep cycle time.

[0121] A sine wave is particularly prominent when the demodulated signal Sd reaches a voltage level at or near the zero point Sz. Therefore, although Figure 16 is a schematic diagram showing the voltage levels corresponding to the demodulated signal Sd under examination, as shown in Figure 16, the voltage level of the demodulated signal Sd is adjusted to or near the zero point Sz before being passed through the low-pass filter 59a. This improves the measurement accuracy of the period of each waveform, making it possible to more reliably distinguish between radar waves emitted by the speed measuring device and radio waves emitted by other equipment.

[0122] For example, if the demodulated signal Sd is an S-shaped waveform with an S-curve characteristic, the zero point is adjusted to a position where the frequency is lower than the maximum value, which is the peak time. If the demodulated signal Sd is an N-shaped waveform with an N-curve characteristic, the zero point is adjusted to a position where the frequency is higher than the maximum value, which is the peak time.

[0123] Adjusting the voltage level to or near the zero point Sz may delay the time required to begin the radio wave analysis, but measuring the period of each waveform of a sine wave shortens the analysis time. Therefore, by using both methods in combination, it is possible to improve the accuracy of radio wave analysis and shorten the sweep cycle time.

[0124] Thus, in this detector 1, the inspection and determination unit 56 fixes the frequency of the received radio waves based on the frequency information Df included in the received information Dr selected by the inspection target selection unit 55, and determines that it is the reception of radar waves from a speed measuring device if a certain number or more of specific frequency components are present in the output of the detection unit 28.

[0125] Thus, in this detector 1, reception determination is made according to the waveform characteristics of the radar wave of the speed measuring device. As a result, the accuracy of determining the radar wave of the speed measuring device is improved, and false alarms can be suppressed.

[0126] Furthermore, the detailed analysis and determination unit 56 has a low-pass filter 59a that passes the signal output by the detection unit 28, and if the number of occurrences of waveform periods corresponding to a specific frequency component is greater than or equal to a certain amount in the signal that has passed through the low-pass filter 59a, it is determined that the signal is a reception of radar waves from a speed measuring device.

[0127] As a result, the amplitude of the demodulated signal Sd exceeds the high-level input voltage VIH and the low-level input voltage VIL during AD conversion. By measuring the time during which the amplitude exceeds VIH, VIL, or both, waveform measurement becomes possible, eliminating the need for calculations such as FFT processing in the control unit 5 and shortening the analysis time. Consequently, the sweep cycle time is shortened.

[0128] Furthermore, the precision analysis and determination unit 56 fixes the frequency to the zero point Sz of the waveform that appears when radio wave reception is detected, or to a nearby point. As a result, the sine wave becomes more prominent, the measurement accuracy of the period of each waveform is improved, and it becomes possible to more reliably distinguish between radar waves emitted by the speed measuring device and radio waves emitted by other devices.

[0129] Here, Figures 17 to 19 show a sine wave in which the demodulated signal Sd is prominently present at or near the zero point Sz. As shown in Figure 17, when the sweep voltage signal SV is swept, the demodulated signal Sd appears in the detected signal Sc at a voltage level above a certain level. At this time, the low-pass filter 59a outputs a demodulated signal Sdf with the high-frequency components cut out.

[0130] When the range E1 of the demodulated signal Sd above a certain voltage level shown in Figure 17 is magnified, as shown in Figure 18, fine waveforms appear at the rising edge of the demodulated signal Sd from the zero point Sz of the demodulated signal Sd after passing through the low-pass filter 59a to the voltage level in its vicinity. As shown in Figure 19, when the range E2 of the demodulated signal Sd from the zero point Sz to the voltage level in its vicinity is further magnified, it can be seen that these fine waveforms are sine waves.

[0131] (Modified version of the second embodiment) In the detector 1 according to the second embodiment, the notification control unit 52 causes the notification unit 6 to notify when the frequency of a specific class is above a threshold, but the notification may be postponed if the frequency of a specific class is not at its maximum value.

[0132] Figure 20 is a flowchart showing the operation of the refinement mode according to a modified example of the second embodiment. As shown in Figure 20, the refinement target selection unit 55 selects a predetermined number of received information Dr (steps S101 to S106). The tuning control unit 57 sets the frequency of the received radio wave to the frequency information Df in the received information Dr, and the signal waveform analysis unit 59b aggregates the frequency distribution of each measured period (steps S201 to S207).

[0133] Once the frequency distribution analysis is complete (Step S207, Yes), the signal waveform analysis unit 59b compares the frequency of a specific class in the frequency frequency distribution with a pre-stored threshold (Step S208). If the frequency of the specific class is greater than or equal to the threshold (Step S208, Yes), the signal waveform analysis unit 59b compares the frequency of the specific class with the frequencies of the other classes (Step S210). If the frequency of the specific class is the maximum value compared to the frequencies of the other classes (Step S210, Yes), the notification control unit 52 causes the notification unit 6 to notify (Step S209).

[0134] On the other hand, if the frequency of a particular class is not at its maximum value (step S210, No), the broadcast control unit 62 does not perform broadcasting processing even if the frequency of a particular class is above the threshold. That is, if all received information Dr has been thoroughly examined (step S109, No), the process returns to step S101 to initialize the received information Dr and start the sweep for the next cycle (steps S102~). If there is any unexamined received information Dr remaining among the received information Dr selected by the examination target selection unit 55 (step S109, Yes), the frequency is fixed to that of the remaining received information Dr (step S201).

[0135] (Third embodiment) A detector 1 according to a third embodiment of the present invention will be described in detail with reference to the drawings. In the third embodiment, components that are the same as those in the first and second embodiments, or have the same functions, are denoted by the same reference numerals and their detailed descriptions are omitted.

[0136] The detector 1 according to the first embodiment determines whether it is receiving radar waves from a speed measuring device by performing a continuity test, which involves a detailed examination based on the continuity of radio waves. The detector 1 according to the second embodiment determines whether it is receiving radar waves from a speed measuring device by performing a waveform test, which involves a detailed examination based on the waveform characteristics of a modulated K-band.

[0137] The detector 1 according to the third embodiment performs both continuity testing and waveform testing, and changes the notification content according to the test results. Figure 21 is a block diagram showing the internal configuration of the detector 1 according to the third embodiment. As shown in Figure 21, this detector 1 is equipped with an input unit 4. The input unit 4 accepts input from the operator regarding the on / off status of false alarm suppression. The on / off status of false alarm suppression can also be rephrased as the strength of false alarm suppression.

[0138] The input unit 4 can be a touch panel, a remote control separate from the detector 1, a physical button attached to the detector 1, or a vehicle display that is connected to the detector 1 in a communicative manner. The inspection and judgment unit 56 of the detector 1 includes a signal monitoring unit 58 for continuity inspection, and a low-pass filter 59a and a signal waveform analysis unit 59b for waveform inspection.

[0139] Furthermore, the notification control unit 52 of the control unit 5 is equipped with a detailed inspection result storage unit 52a. The detailed inspection result storage unit 52a stores the results of the continuity inspection by the signal monitoring unit 58 and the waveform inspection results by the signal waveform analysis unit 59b. The notification control unit 52 outputs information corresponding to the results of the continuity inspection and the waveform inspection to the notification unit 6.

[0140] Figures 22 and 23 are flowcharts showing the operation of the detector 1 equipped with this input unit 4 in the inspection mode. As shown in Figures 22 and 23, a sweep process is performed using the radio wave reception mode from steps S101 to S105 (step S301), and a predetermined number of received information Dr is selected by the inspection target selection unit 55 (step S302). In addition, the inspection result storage unit 52a initializes the continuity inspection result information and the waveform inspection result information (step S303).

[0141] Then, the detailed inspection and determination unit 56 performs the continuity check in steps S107 and S108 (step S304). If the continuity check indicates that the demodulated signal Sd has continued for a predetermined time or longer (step S305, Yes), the detailed inspection result storage unit 52a stores the continuity check result information indicating that reception was received (step S306).

[0142] Once the continuity check is complete, the detailed examination and determination unit 56 performs the waveform checks in steps S201 to S208 (step S307). If the waveform checks show that the frequency of a specific class is above a threshold (step S308, Yes), the detailed examination result storage unit 52a stores waveform check result information indicating that reception was received (step S309).

[0143] If there are any unexamined received information Drs remaining (Step S310, Yes), the continuity check and waveform check from Steps S304 to S309 are performed for the next received information Dr. Once the examination of all received information Drs is complete (Step S310, No), the combination of information stored in the examination result storage unit 52a is determined (Steps S311 to 315).

[0144] In other words, if the continuity check result information indicating that a reception has been received is not stored in the detailed examination result storage unit 52a (step S311, No), the process returns to step S101, the reception information Dr is initialized, and the sweep for the next cycle is started (steps S301~).

[0145] If the verification result storage unit 52a stores continuity inspection result information indicating reception (step S311, Yes), the input unit 4 confirms the false alarm suppression received (step S312). If false alarm suppression is off (step S312, No), the notification control unit 52 does not determine that it is a radar wave from the speed measuring device, but outputs information to the notification unit 6 indicating that a radio wave has been received (step S314). Then, returning to step S101, the reception information Dr is initialized and the sweep for the next cycle is started (steps S301~).

[0146] If false alarm suppression is turned on (step S312, Yes), the waveform inspection result information in the detailed result storage unit 52a is checked (step S313). If waveform inspection result information indicating reception is stored in the detailed result storage unit 52a (step S313, Yes), the notification control unit 52 outputs information to the notification unit 6 indicating that the radar wave of the speed measuring device has been received (step S315). Then, returning to step S101, the reception information Dr is initialized and the sweep for the next cycle is started (steps S301~).

[0147] On the other hand, if no waveform inspection result information indicating reception is stored in the detailed inspection result storage unit 52a (step S313, No), the process returns to step S101 to initialize the reception information Dr and start the sweep for the next cycle (steps S301~).

[0148] Furthermore, if false alarm suppression is enabled when input unit 4 receives a signal, and the number of occurrences of waveform periods corresponding to a specific frequency component exceeds a certain level, information indicating that it is a radar wave from a speed measuring device may be immediately broadcast without completing all of the selected received information Dr. If false alarm suppression is enabled when input unit 4 receives a signal, the continuity check may be omitted.

[0149] Furthermore, if the false alarm suppression is turned off when input unit 4 receives the signal, waveform inspection may be omitted. If waveform inspection is omitted, if radio wave reception is detected to continue for a predetermined period of time, the information may be immediately notified without completing all of the selected received information Dr.

[0150] (Modification 1 of the third embodiment) The radar waves emitted by the speed measuring device include unmodulated waves in the K-band. In waveform analysis of these unmodulated K-band radar waves, the number of occurrences of waveform periods for specific frequency components is below a certain level. Therefore, when false alarm suppression is turned on, the detailed analysis and judgment unit 56 re-examines the results of the continuity inspection and the frequency information Df included in the received information Dr if the number of occurrences of waveform periods corresponding to a specific frequency component is below a certain level.

[0151] Figure 24 is a flowchart showing the operation of the inspection mode of the detector 1 according to this modified example. After completing the radio wave reception mode and inspection mode from steps S301 to S310 (step S321), the detector 1 determines whether the continuity inspection result information indicating reception is stored (step S322). If the continuity inspection result information indicating reception is stored (step S322, Yes), and if false alarm suppression is also turned on (step S323, Yes), it determines whether the waveform inspection result information indicating reception is stored (step S324).

[0152] If waveform inspection result information indicating reception is not stored (step S324, No), it is determined that the frequency indicated by frequency information Df included in the reception information Dr is within a more specific range within the K band (step S325). The notification control unit 52 stores thresholds indicating the lower and upper limits of the specific range, and determines by comparison whether the frequency of frequency information Df exceeds the lower threshold and the frequency of frequency information Df falls below the upper threshold. It is preferable that the types of frequency information Df and thresholds be the same, but if they are of different types, the notification control unit 52 can unify them by conversion.

[0153] The notification control unit 52, if the frequency information Df included in the received information Dr indicates that the frequency is within a more specific range within the K band (step S325, Yes), notifies information indicating that the radar wave of the speed measuring device has been received (step S326). Then, returning to step S101, the received information Dr is initialized and the sweep for the next cycle is started (steps S301~).

[0154] If the frequency information Df included in the received information Dr is not within a specific range within the K band (step S325, No), the notification control unit 52 does not conclude that it is a radar wave from the speed measuring device, and outputs information to the notification unit 6 indicating that a radio wave has been received (step S327). Then, returning to step S101, the received information Dr is initialized and the sweep for the next cycle is started (steps S301~).

[0155] (Modification 2 of the third embodiment) Although it is in the K-band, the content of the information to be reported and whether or not it needs to be reported may be changed to correspond to unmodulated radar waves. Figure 25 is a flowchart showing another example of operation 1 of the inspection mode of the detector 1 according to a modified example of the third embodiment.

[0156] After completing the radio wave reception mode and inspection mode from steps S301 to S310 (step S321), the detector 1 determines whether the continuity inspection result information indicating reception is stored (step S322). If the continuity inspection result information indicating reception is stored (step S322, Yes), it further determines whether false alarm suppression is turned on (step S323).

[0157] If false alarm suppression is not turned on (step S323, No), the system does not definitively identify the signal as a radar wave from the speed measuring device, but instead outputs information to the notification unit 6 indicating that a radio wave has been received (step S327). Then, the system returns to step S101 to initialize the received information Dr and start the sweep for the next cycle (steps S301~).

[0158] If false alarm suppression is turned on (step S323, Yes), the notification control unit 52 determines whether the frequency indicated by the frequency information Df included in the received information Dr is within a more specific range within the K band (step S325). If the notification control unit 52 determines that the frequency indicated by the frequency information Df included in the received information Dr is within a more specific range within the K band (step S325, Yes), it further determines whether the detected signal S is an unmodulated wave (step S328).

[0159] If the detected signal S is an unmodulated wave (step S328, Yes), information indicating that the radar wave of the speed measuring device has been received is broadcast (step S326). Then, the process returns to step S101 to initialize the received information Dr and start the sweep for the next cycle (steps S301~).

[0160] On the other hand, if the frequency information Df included in the received information Dr is within a more specific range within the K band (step S325, Yes), but the detected signal S is not an unmodulated wave (step S328, No), the notification control unit 52 does not broadcast the information, returns to step S101, initializes the received information Dr, and starts the sweep for the next cycle (steps S301~).

[0161] Furthermore, even if the frequency indicated by the frequency information Df included in the received information Dr is not within a more specific range within the K band (step S325, No), the notification control unit 52 further determines whether the detected signal S is an unmodulated wave (step S329).

[0162] If the detected signal S is an unmodulated wave (step S329, Yes), it is not determined to be a radar wave from the speed measuring device, and information indicating that a radio wave has been received is output to the notification unit 6 (step S327). Then, the process returns to step S101, the received information Dr is initialized, and the sweep for the next cycle is started (steps S301~).

[0163] On the other hand, if the frequency information Df included in the received information Dr is not within a specific range within the K band (step S325, No), and the detected signal S is not an unmodulated wave (step S329, No), the notification control unit 52 does not broadcast the information, returns to step S101, initializes the received information Dr, and starts the sweep for the next cycle (steps S301~).

[0164] (Modification 3 of the third embodiment) Although it is in the K-band, the content of the information to be reported and whether or not it needs to be reported may be changed to correspond to unmodulated radar waves. Figure 26 is a flowchart showing another example of operation 2 of the inspection mode of the detector 1 according to a modified example of the third embodiment.

[0165] After completing the radio wave reception mode and inspection mode from steps S301 to S310 (step S321), the detector 1 determines whether the continuity inspection result information indicating reception is stored (step S322). If the continuity inspection result information indicating reception is stored (step S322, Yes), it further determines whether false alarm suppression is turned on (step S323).

[0166] If false alarm suppression is not turned on (step S323, No), the system does not definitively identify the signal as a radar wave from the speed measuring device, but instead outputs information to the notification unit 6 indicating that a radio wave has been received (step S327). Then, the system returns to step S101 to initialize the received information Dr and start the sweep for the next cycle (steps S301~).

[0167] If false alarm suppression is turned on (step S323, Yes), it is determined whether the frequency indicated by the frequency information Df included in the received information Dr is within a more specific range within the K band (step S325).

[0168] The notification control unit 52 determines, if the frequency information Df included in the received information Dr is within a more specific range within the K band (step S325, Yes), whether the detected signal S is an unmodulated wave (step S328). If the detected signal S is an unmodulated wave (step S328, Yes), it notifies information indicating that the radar wave of the speed measuring device has been received (step S326). Then, it returns to step S101 to initialize the received information Dr and start the sweep for the next cycle (steps S301~).

[0169] On the other hand, if the frequency information Df included in the received information Dr is within a more specific range within the K band (step S325, Yes), but the detected signal S is not an unmodulated wave (step S328, No), the notification control unit 52 does not broadcast the information, returns to step S101, initializes the received information Dr, and starts the sweep for the next cycle (steps S301~).

[0170] Furthermore, even if the frequency indicated by the frequency information Df included in the received information Dr is not within a more specific range within the K band (step S325, No), the notification control unit 52 further determines whether the detected signal S is an unmodulated wave (step S329).

[0171] If the detected signal S is not an unmodulated wave (step S329, No), information indicating that the radar wave of the speed measuring device has been received is broadcast (step S326). Then, the process returns to step S101 to initialize the received information Dr and start the sweep for the next cycle (steps S301~).

[0172] On the other hand, if the frequency information Df included in the received information Dr is not within a specific range within the K band (step S325, No), and the detected signal S is an unmodulated wave (step S329, Yes), the notification control unit 52 does not broadcast the information, returns to step S101, initializes the received information Dr, and starts the sweep for the next cycle (steps S301~).

[0173] (Modification 4 of the third embodiment) Although it is in the K-band, the content of the information to be reported and whether or not it needs to be reported may be changed to correspond to unmodulated radar waves. Figure 27 is a flowchart showing another example of operation 3 of the inspection mode of the detector 1 according to a modified example of the third embodiment.

[0174] After completing the radio wave reception mode and inspection mode from steps S301 to S310 (step S321), the detector 1 determines whether the continuity inspection result information indicating reception is stored (step S322). If the continuity inspection result information indicating reception is stored (step S322, Yes), it further determines whether false alarm suppression is turned on (step S323).

[0175] If false alarm suppression is not turned on (step S323, No), the system does not definitively identify the signal as a radar wave from the speed measuring device, but instead outputs information to the notification unit 6 indicating that a radio wave has been received (step S327). Then, the system returns to step S101 to initialize the received information Dr and start the sweep for the next cycle (steps S301~).

[0176] If false alarm suppression is turned on (step S323, Yes), it is determined whether the frequency indicated by the frequency information Df included in the received information Dr is within a more specific range within the K band (step S325).

[0177] The notification control unit 52 determines, if the frequency information Df included in the received information Dr is within a more specific range within the K band (step S325, Yes), whether the detected signal S is an unmodulated wave (step S328). If the detected signal Sc is an unmodulated wave (step S328, Yes), it notifies information indicating that the radar wave of the speed measuring device has been received (step S326). At this time, the notification content includes information identifying the speed measuring device that emits an unmodulated radar wave in the K band. Then, it returns to step S101 to initialize the received information Dr and start the sweep for the next cycle (steps S301~).

[0178] On the other hand, if the frequency information Df included in the received information Dr is within a more specific range within the K band (step S325, Yes), but the detected signal S is not an unmodulated wave (step S328, No), the notification control unit 52 does not broadcast the information, returns to step S101, initializes the received information Dr, and starts the sweep for the next cycle (steps S301~).

[0179] Furthermore, even if the frequency indicated by the frequency information Df included in the received information Dr is not within a more specific range within the K band (step S325, No), the notification control unit 52 further determines whether the detected signal S is an unmodulated wave (step S329).

[0180] If the detected signal S is not an unmodulated wave (step S329, No), information indicating that the radar wave of a speed measuring device has been received is broadcast (step S326). At this time, the broadcast content includes information identifying the speed measuring device that emits a modulated radar wave in the K-band. Then, the system returns to step S101 to initialize the received information Dr and start the sweep for the next cycle (steps S301~).

[0181] On the other hand, if the frequency information Df included in the received information Dr is not within a specific range within the K band (step S325, No), and if the detected signal S is an unmodulated wave (step S329, Yes), the notification control unit 52 does not broadcast the information, returns to step S101, initializes the received information Dr, and starts the sweep for the next cycle (steps S301~).

[0182] (Fourth embodiment) A detector 1 according to the fourth embodiment of the present invention will be described in detail with reference to the drawings. In the fourth embodiment, components that are the same as those in the first to third embodiments or have the same functions will be denoted by the same reference numerals and their detailed descriptions will be omitted.

[0183] The detector 1 in the first to third embodiments was described using the reception of modulated radar waves in the K band as an example. However, it is not limited to this, and the detector may also detect and broadcast information based on the reception of unmodulated radar waves in the X band emitted by a speed measuring device.

[0184] Figure 28 is a block diagram showing the configuration of the detector 1 according to the fourth embodiment. As shown in Figure 28, the first-stage local oscillator 23 is equipped with a switchable X-band oscillator 23X and a K-band oscillator 23K.

[0185] The X-band oscillator 23X generates a first-stage local oscillator signal LFf, which is mixed with the X-band received signal RF, and inputs it to the first-stage mixer 24. The K-band oscillator 13b generates a first-stage local oscillator signal LFf, which is mixed with the K-band received signal RF, and inputs it to the first-stage mixer 24. If the first-stage intermediate frequency signal IFs is set to 1000 MHz, for example, and the X-band is 10.525 GHz and the K-band is 24.100 GHz, then the X-band oscillator 23X generates a first-stage local oscillator signal LFf of 9.525 GHz, and the K-band oscillator 23K generates a first-stage local oscillator signal LFf of 23.100 GHz.

[0186] Figure 29 is a flowchart showing the operation of the detector 1 in the fourth embodiment. As shown in Figure 29, the tuning control unit 57 reads out the next band information Db (step S401), generates a sweep start control signal Cs (step S402), and inputs it to the first-stage local oscillator unit 23 (step S403). In step S401, the next band information Db is information indicating the type of band to be received and examined in the radio wave reception mode and examination mode of the next cycle. The tuning control unit 57 stores this next band information Db. The tuning control unit 57 generates a sweep start control signal Cs that includes information identifying the band indicated by this next band information Db.

[0187] The first-stage local oscillator 23 inputs the first-stage local oscillator signal LFf corresponding to the band indicated by the sweep start control signal Cs to the first-stage mixer 24 during the radio wave reception mode and scrutiny mode of the next cycle (step S404). That is, if the band indicated by the sweep start control signal Cs is the X band, the X band oscillator 23X generates the first-stage local oscillator signal LFf and inputs it to the first-stage mixer 24. If the band indicated by the sweep start control signal Cs is the K band, the K band oscillator 23K generates the first-stage local oscillator signal LFf and inputs it to the first-stage mixer 24.

[0188] When the refinement mode ends (step S405, Yes), the refinement unit 51 rewrites the next band information Db with different content (step S406). If the next band information Db indicates the K band, it is rewritten to indicate the X band. If the next band information Db indicates the X band, it is rewritten to indicate the K band. Then, the process returns to step S401, and the next cycle of radio wave reception mode and refinement mode is started.

[0189] Thus, in this detector 1, the first-stage local oscillator 23 is configured to alternately change and output signals of different frequencies each time the sweep is repeated. Specifically, the first-stage local oscillator signals LFs corresponding to the X-band and K-band frequencies are alternately changed and output. This makes it possible to detect radar waves from multiple types of speed measuring devices with a single detector 1, and in continuity testing, the cycle time can be shortened in each band by narrowing down the examination to a predetermined number of received information Dr.

[0190] (Modification of the fourth embodiment) In the detector 1 of the fourth embodiment, any of the methods of the continuity inspection of the first embodiment, the waveform inspection of the second embodiment, or the method of the third embodiment can be used for the X-band inspection. However, the speed measuring device may emit unmodulated X-band radar waves. Therefore, it is preferable to use a waveform inspection that can handle unmodulated waves.

[0191] Figure 30 is a flowchart showing the operation of a waveform inspection according to a modified example of the fourth embodiment. As shown in Figure 30, once the sweep from steps S101 to S106 is completed and the received information Dr is selected (step S410), the tuning control unit 57 sets the frequency of the radio wave to be received to the frequency information Df in the received information Dr (step S411), and then modulates the second stage local oscillator signal until the demodulated signal Sd reaches a voltage level at or near the zero point Sz (step S413, Yes) (step S412).

[0192] When the demodulated signal Sd reaches a voltage level at or near the zero point Sz (step S413, Yes), the low-pass filter 59a cuts out high-frequency components from the demodulated signal Sd output by the detection unit 28 (step S414). The signal waveform analysis unit 59b detects a waveform from the demodulated signal Sd that has passed through the low-pass filter 59a (step 415). After passing through the low-pass filter 59a, in the case of an unmodulated X-band wave, no waveform appears in the demodulated signal Sd, and the demodulated signal Sd becomes linear.

[0193] If no waveform appears in the demodulated signal Sd (step S415, No), the notification control unit 52 causes the notification unit 6 to notify (step S416). That is, the detector 1, after careful examination, determines that it has received radar waves emitted by the speed measuring device and notifies the information. Then, it returns to step S101 to initialize the received information Dr and start the sweep for the next cycle (steps S102~).

[0194] If a waveform appears in the demodulated signal Sd (step S415, Yes), and if there are any unexamined received information Drs among the received information Drs selected by the examination target selection unit 55 (step S417, Yes), the examination of the remaining received information Drs continues (steps S411~). On the other hand, if the examination of all received information Drs is completed (step S417, No), the process returns to step S101, the received information Drs are initialized, and the sweep for the next cycle is started (steps S102~).

[0195] Thus, when the speed measuring device emits X-band radar waves, it is sufficient to determine whether or not the signal is unmodulated by setting the demodulated signal Sd to a voltage level at or near the zero point Sz and passing it through the low-pass filter 59a. This improves the accuracy of the analysis while shortening the analysis time.

[0196] (Fifth embodiment) A detector 1 according to the fifth embodiment of the present invention will be described in detail with reference to the drawings. In the fifth embodiment, components that are the same as those in the first to fourth embodiments or have the same functions will be denoted by the same reference numerals and their detailed descriptions will be omitted.

[0197] In the fourth embodiment of the detector 1, the first-stage local oscillator signal LFs corresponding to the X-band and K-band frequencies is alternately changed and output. However, in the fifth embodiment of the detector 1, if a detailed examination confirms or suggests that the signal is a radar wave from a speed measuring device, the detector receives radio waves in the same band in the next radio wave reception mode cycle without changing the band.

[0198] Figure 31 is a flowchart showing the operation of the detector 1 according to the fifth embodiment. As shown in Figure 31, the tuning control unit 57 reads out the next band information Db (step S501), generates a sweep start control signal Cs (step S502), and inputs it to the first-stage local oscillator unit 23 (step S503). In step S501, the next band information Db is information indicating the type of band to be received and examined in the radio wave reception mode and examination mode of the next cycle. The tuning control unit 57 stores this next band information Db. The tuning control unit 57 generates a sweep start control signal Cs that includes information identifying the band indicated by this next band information Db.

[0199] The first-stage local oscillator 23 inputs the first-stage local oscillator signal LFf corresponding to the band indicated by the sweep start control signal Cs to the first-stage mixer 24 during the radio wave reception mode and scrutiny mode of the next cycle (step S504). That is, if the band indicated by the sweep start control signal Cs is the X band, the X band oscillator 23X generates the first-stage local oscillator signal LFf and inputs it to the first-stage mixer 24. If the band indicated by the sweep start control signal Cs is the K band, the K band oscillator 23K generates the first-stage local oscillator signal LFf and inputs it to the first-stage mixer 24.

[0200] When the refinement mode ends (step S505, Yes), if the refinement unit 51 determined in the refinement mode that the signal was from a radar wave of a speed measuring device (step S506, Yes), it maintains the contents of the next band information Db (step S507). Then, it returns to step S401 and starts the radio wave reception mode and refinement mode for the next cycle.

[0201] On the other hand, when the refinement mode ends (step S505, Yes), if the refinement unit 51 has not determined that the signal is a radar wave from a speed measuring device during the refinement mode (step S506, No), it rewrites the next band information Db to different content (step S508). Then, it returns to step S401 and starts the radio wave reception mode and refinement mode for the next cycle.

[0202] In step S506, the determination that the signal is a radar wave from a speed measuring device includes not only confirmation by waveform inspection, but also cases where the demodulated signal Sd continues for a predetermined time or longer in the continuity inspection.

[0203] As a determination method, for example, the signal monitoring unit 58, the signal waveform analysis unit 59b, or both may store radar wave reception information Dd indicating that they have determined the signal to be a radar wave from a speed measuring device. The refinement unit 51 maintains the contents of the next band information Db if radar wave reception information Dd exists. When starting the radio wave reception mode and refinement mode for the next cycle, the refinement unit 51 clears the reception information Dd.

[0204] Thus, the first-stage local oscillator 23 outputs a signal without changing the band during the next sweep when the analysis unit 51 determines that it has received a radar wave from the speed measuring device. As a result, even when monitoring multiple bands such as the X-band and K-band, the bands that are most likely to receive radar waves from the speed measuring device can be closely monitored, thereby improving the ability to monitor radar waves from the speed measuring device.

[0205] (Other embodiments) As described above, several embodiments of the present invention have been presented, but these embodiments are presented as examples and are not intended to limit the scope of the invention. Specifically, combinations of all or any of the first to sixth embodiments and their variations are also included. The embodiments described above can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the scope of the invention. These embodiments and their variations are included in the scope and essence of the invention, as well as in the claims and their equivalents.

[0206] For example, when a demodulated signal Sd, which is a signal with a voltage level above a certain level, i.e., a signal exceeding white noise Sn, is received, reception information Dr is generated. Alternatively, the frequency and voltage of all radio waves, including white noise Sn, may be sampled and stored, and a predetermined number of high-voltage signals may be picked from this sample. In other words, the reception information storage unit 54 may store all radio waves, including white noise Sn, as reception information Dr, and the reception determination unit 53 that distinguishes between white noise Sn and demodulated signal Sd may be eliminated. [Explanation of Symbols]

[0207] 1 detector 10 cabinets 11 Back 12 Front 13 Reception Area 14 screens 15 speakers 16 lamps 2. Radio wave receiving system 21 Receiving unit 22 Receiving detection unit 23. First stage local oscillator 24. Mixed section of the first stage 25 Second stage local oscillator 26. Second stage mixing section 27 Sweep Control Unit 28 Detection section 3. Positioning signal receiving system 4 Input section 5. Control Unit 51. Inspection Department 52 Notification Control Unit 53 Reception determination unit 54 Received Information Storage Unit 55 Selection of items to be examined 56. Examination and Judgment Department 57 Synchronization Control Unit 58 Signal Monitoring Unit 59a Low-pass filter 59b Signal waveform analysis section 6 Hochi Department RF Received Signal LFf is the local oscillator signal of the first stage. IFf First stage intermediate frequency signal LFs Second stage local oscillator signal IFs: Second stage intermediate frequency signal fb predetermined frequency range fs starting frequency fe Termination frequency SV sweep voltage signal SVs Start sweep voltage signal SVe termination sweep voltage signal CV constant voltage signal AV adjustment signal Cs sweep start control signal Ce sweep completion notification signal Cc Specific Frequency Continuous Control Signal Sc detection signal Sn White Noise SL Low-Frequency Noise Sw swell signal Sd demodulated signal Dr. Received Information Df frequency information Ds signal strength level Db Next band information Dd Radar wave reception information Dd

Claims

1. A detector installed on a vehicle that detects radar waves from a speed measuring device, The receiving section, including the antenna, A receiving detection unit that generates an intermediate frequency signal while sweeping a predetermined frequency range up to the terminal frequency, and detects radio wave reception based on the intermediate frequency signal, After the receiving detection unit sweeps up to the termination frequency, a reconnaissance unit determines whether the radio wave reception detected by the receiving detection unit is the reception of the radar wave of the speed measuring device. Equipped with, The aforementioned inspection unit determines whether a predetermined number of radio waves with high signal strength levels among those detected during the sweep are radar waves from the speed measuring device. A detector characterized by the following.

2. The aforementioned inspection unit determines, in the order in which the radio waves detected during the sweep had high signal strength levels, whether they were received from the radar wave of the speed measuring device. The detector according to claim 1, characterized by the following:

3. The aforementioned inspection unit, A storage unit that stores, as reception information, a set of frequency information that identifies the frequency at which the radio wave reception was detected and the radio wave intensity level at which the radio wave reception was detected. A selection unit for reviewing data sweeps up to the aforementioned termination frequency and then selects a predetermined number of received data in descending order of radio wave intensity level. After sweeping up to the aforementioned termination frequency, the frequency of the radio wave to be received is fixed based on the frequency information included in the received information selected by the selection target unit, and the selection determination unit determines whether it is a radar wave from a speed measuring device. Having The detector according to claim 1, characterized by the following:

4. The receiving unit receives radio waves and converts them into a received signal. The reception detection unit is, A multi-stage local oscillator, each outputting a signal of a predetermined frequency, The first stage mixer mixes the received signal with a signal of the frequency output by the first stage local oscillator to output an intermediate frequency signal of the first stage, A second or subsequent stage mixing unit mixes the signal of the frequency output by the local oscillator of the same stage with the intermediate frequency signal of the preceding stage to output the intermediate frequency signal of the next stage, A sweep control unit that sweeps the frequency of the signal output by any of the local oscillators from the second stage onward to the termination frequency of a predetermined frequency band, Having A detector according to claim 1 or 3, characterized by the above.

5. The receiving unit receives radio waves and converts them into a received signal. The reception detection unit is, A two-stage local oscillator, each outputting a signal of a predetermined frequency, The first stage mixer mixes the received signal with a signal of the frequency output by the first stage local oscillator to output an intermediate frequency signal of the first stage, The second stage mixer mixes the frequency signal output by the second stage local oscillator with the intermediate frequency signal of the first stage to output the intermediate frequency signal of the next stage, A sweep control unit that sweeps the frequency of the signal output by the second-stage local oscillator up to the termination frequency of a predetermined frequency band, Having A detector according to claim 1 or 3, characterized by the above.

6. The aforementioned inspection unit fixes the frequency to a predetermined number of radio waves with high radio wave intensity levels, and when radio wave reception is detected continuously for a predetermined time, it determines that it is the reception of radar waves from the speed measuring device. A detector according to claim 1 or 3, characterized by the above.

7. The frequencies of a predetermined number of radio waves with high signal strength levels are the frequencies at the peak of the signal strength when the radio waves were received. The detector according to claim 6, characterized by the following:

8. The radio waves detected during the sweep are undulating signals generated by low-frequency noise superimposed when radio waves are received while sweeping. The aforementioned inspection unit identifies from the undulation signal the frequency at which the radio wave with a high signal strength level is generated when the low-frequency noise is not superimposed, and makes a determination regarding the radio wave at that frequency. The detector according to claim 6, characterized by the following:

9. The aforementioned analysis unit identifies the zero signal level included in the undulation signal, excluding the range of white noise, and sets the frequency shifted by a pre-stored offset value from that zero signal level to be the frequency of the radio wave with a high radio wave intensity level. The detector according to claim 8, characterized by the following:

10. The receiving detection unit has a detection unit that demodulates the intermediate frequency signal, The aforementioned inspection unit determines that if a certain number or more of specific frequency components are present in the output of the detection unit, it is the reception of radar waves from the speed measuring device. A detector according to claim 1 or 3, characterized by the above.

11. The aforementioned inspection unit has a low-pass filter that passes the signal output by the detection unit, and if the number of occurrences of waveform periods corresponding to a specific frequency component is greater than or equal to a certain amount in the signal that has passed through the low-pass filter, it is determined that the signal is a reception of the radar wave from the speed measuring device. The detector according to claim 10, characterized by the following:

12. The aforementioned inspection unit fixes the frequency at or near the zero point of the waveform that appears when the radio wave reception is detected. The detector according to claim 11, characterized by the following:

13. When the waveform detected upon receiving the aforementioned radio waves is an S-shaped waveform that drops below zero before rising towards a peak, the zero point is the zero point at a position where the frequency is lower than that of the peak. When the waveform detected upon reception of the aforementioned radio waves is an N-shaped waveform that rises towards a peak and then drops below the zero point, the zero point is the zero point at a position where the frequency is higher than that of the peak. The detector according to claim 12, characterized by the following:

14. The aforementioned inspection unit determines that if a certain number or more of the specified frequency components are present and are more numerous than other frequency components, it is a reception of radar waves from the speed measuring device. The detector according to claim 10, characterized by the following:

15. The aforementioned inspection unit, when the frequency of the radio waves detected by the receiving detection unit is within a specific range, determines that the reception of radio waves is from the radar wave of the speed measuring device, even if the output of the detection unit has fewer than a certain number of specific frequency components, if the radio wave reception is detected continuously for a predetermined time. The detector according to claim 10, characterized by the following:

16. The aforementioned inspection unit fixes the frequency to a predetermined number of radio waves with high radio wave intensity levels, and determines that the reception of radio waves is received by the speed measuring device if the reception detection unit detects that radio wave reception continues for a predetermined time, that the frequency of the radio wave detected by the reception detection unit is within a specific range, and that the radio wave detected by the reception detection unit is an unmodulated wave. The detector according to claim 6, characterized by the following:

17. Equipped with a broadcasting unit to disseminate information, The aforementioned inspection unit fixes the frequency to a predetermined number of radio waves with high radio wave intensity levels, detects radio wave reception for a predetermined period of time, determines whether the frequency of the radio wave detected by the reception detection unit is within a specific range, and determines whether the radio wave detected by the reception detection unit is an unmodulated wave. The notification unit determines that, if the results of the analysis unit indicate that radio wave reception is detected for a predetermined period of time, but the frequency of the radio wave detected by the reception detection unit is not within a specific range, and the radio wave detected by the reception detection unit is an unmodulated wave, then the radio wave detection information does not identify it as reception of the radar wave of the speed measuring device. The detector according to claim 6, characterized by the following:

18. Equipped with a broadcasting unit to disseminate information, The aforementioned inspection unit fixes the frequency to a predetermined number of radio waves with high radio wave intensity levels, detects radio wave reception for a predetermined period of time, determines whether the frequency of the radio wave detected by the reception detection unit is within a specific range, and determines whether the radio wave detected by the reception detection unit is an unmodulated wave. The notification unit shall, if the results of the analysis unit indicate that radio wave reception is detected for a predetermined period of time, but the frequency of the radio wave detected by the reception detection unit is not within a specific range, and the radio wave detected by the reception detection unit is not an unmodulated wave, then provide information indicating that it is the reception of a radar wave from the speed measuring device. The detector according to claim 6, characterized by the following:

19. Equipped with a broadcasting unit to disseminate information, The aforementioned inspection unit fixes the frequency to a predetermined number of radio waves with high radio wave intensity levels, detects radio wave reception for a predetermined period of time, determines whether the frequency of the radio wave detected by the reception detection unit is within a specific range, and determines whether the radio wave detected by the reception detection unit is an unmodulated wave. The notification unit, when the results of the detailed analysis unit indicate that radio wave reception has been detected for a predetermined period of time, identifies the type of speed measuring device and notifies information indicating that it is a radar wave from the speed measuring device, depending on whether the frequency of the radio wave detected by the reception detection unit is within a specific range and whether the radio wave detected by the reception detection unit is an unmodulated wave. The detector according to claim 6, characterized by the following:

20. The aforementioned first-stage local oscillator alternately changes and outputs signals of different bands each time the sweep is repeated. The detector according to claim 4, characterized by the following:

21. The first-stage local oscillator, when the analysis unit determines that it has received a radar wave from the speed measuring device, outputs a signal without changing the band during the next sweep. The detector according to claim 20, characterized by the following:

22. The system includes a notification unit that notifies information when it is determined that the radar wave of the speed measuring device has been received. A detector according to claim 1 or 3, characterized by the above.

23. The notification unit shall notify information when it is determined that the radar wave of the speed measuring device has been received a predetermined number of times during a series of sweeps. The detector according to claim 22, characterized by the following:

24. A detector installed on a vehicle that detects radar waves from a speed measuring device, The receiving section, including the antenna, A receiving detection unit having a detection unit that generates an intermediate frequency signal while sweeping a predetermined frequency range up to the termination frequency, and demodulates the intermediate frequency signal with the detection unit to detect radio wave reception, After the reception detection unit sweeps up to the termination frequency, a refinement unit determines whether the radar wave of the speed measuring device has been received, An input section that accepts the user's selection of the strength of false alarm suppression, Equipped with, The aforementioned inspection unit, During the sweep, a predetermined number of radio waves with high signal strength levels are selected to determine whether they are radar waves from the speed measuring device. A storage unit that stores, as reception information, a set of frequency information that identifies the frequency at which the radio wave reception was detected and the radio wave intensity level at which the radio wave reception was detected. A selection unit for reviewing data sweeps up to the aforementioned termination frequency and then selects a predetermined number of received data in descending order of radio wave intensity level. After sweeping up to the aforementioned termination frequency, the frequency of the radio wave to be received is fixed based on the frequency information included in the received information selected by the selection target unit, and the selection determination unit determines whether it is a radar wave from a speed measuring device. It has, If the input unit accepts the selection of "weak" false alarm suppression, The detailing and determination unit fixes the frequency of the received radio wave to the frequency based on the frequency information included in the received information selected by the detailing target selection unit, and when radio wave reception is detected to continue for a predetermined time, it determines that it is the reception of radar waves from the speed measuring device. If the input unit receives a selection for strong false alarm suppression, The aforementioned inspection and determination unit has a low-pass filter that passes the signal output by the detection unit, and based on the reception information selected by the inspection target selection unit, it fixes the frequency to the zero point or its vicinity of the waveform that appears when radio wave reception is detected, and if the number of occurrences of waveform periods corresponding to a specific frequency component is greater than or equal to a certain amount after passing through the low-pass filter, it determines that it is the reception of radar waves from the speed measuring device. A detector characterized by the following.

Images