Radar detector

Abstract

To provide a radar detector that reduces false determinations that an electric wave emitted from another device is an electric wave from a vehicle rate measuring device.SOLUTION: The radar detector includes a reception unit, a first signal mixing unit, a second signal mixing unit, a first detection unit, a detection frequency specification unit, a second detection unit, and a modulation wave determination unit. The second detection unit detects a second detection signal changeable according to the amplitude of a first detection signal from the first detection signal, and outputs the second detection signal. The modulation wave determination unit determines whether a target electric wave in a reception electric signal is a modulation signal on the basis of a first signal level and a second signal level.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to radar detectors. [Background technology]

[0002] 2. Description of the Related Art Radar detectors that are configured to detect microwave radio waves emitted from vehicle speed measuring devices are known. There are multiple types of radio waves with different frequency bands emitted by vehicle speed measuring devices. Radar detectors for detecting each of these multiple types of radio waves (e.g., X-band radio waves, K-band radio waves, etc.) have been proposed (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6810843 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the above-mentioned radar detector receives radio waves emitted from a device other than the vehicle speed measuring device and in the same frequency band as the radio waves emitted by the vehicle speed measuring device, there is a possibility that the radar detector may mistakenly determine that it has detected radio waves from the vehicle speed measuring device.

[0005] For example, the motion sensor of a vending machine uses radio waves in the same frequency band as K-band radio waves, so if a radar detector detects radio waves emitted by a motion sensor of a vending machine, it may mistakenly determine that it has detected K-band radio waves from a vehicle speed measurement device.

[0006] Therefore, it is desirable to provide a radar detector that, when detecting radio waves from a vehicle speed measurement device, which is a target radio wave, prevents radio waves emitted by other devices from being mistakenly determined to be radio waves from a vehicle speed measurement device. [Means for solving the problem]

[0007] A radar detector according to one aspect of the present disclosure includes a receiving unit, a first signal mixing unit, a second signal mixing unit, a first detection unit, a detection frequency identification unit, a second detection unit, and a modulated wave determination unit. The receiving unit is configured to receive received radio waves including the target radio waves and output the received signal. The first signal mixing unit is configured to output a first mixed signal obtained by mixing a signal of a first frequency with the received signal. The first frequency is determined according to the frequency of the target radio waves. The second signal mixing unit is configured to output a second mixed signal obtained by mixing a signal of a second frequency with the first mixed signal. The second signal mixing unit is configured to be able to change the second frequency.

[0008] The first detection unit is configured to detect a signal of a predetermined frequency band including a predetermined intermediate frequency from the second mixed signal. The first detection unit is configured to output a first detected signal obtained by detection. The detection frequency identification unit is configured to control the second signal mixing unit to change the second frequency and to identify a detection frequency corresponding to the second frequency when the first detected signal becomes a signal of the intermediate frequency. The second detection unit is configured to detect a second detected signal from the first detected signal, the second detected signal changing according to the amplitude of the first detected signal, and output the second detected signal.

[0009] The modulated wave determination unit is configured to determine whether the target radio wave included in the received radio wave is a modulated wave based on a first signal level and a second signal level. The first signal level corresponds to the amplitude of the second detection signal when the second frequency is not the detection frequency. The second signal level corresponds to the amplitude of the second detection signal when the second frequency is the detection frequency.

[0010] This radar detector includes a second detection unit, and can extract the second detection signal from the first detection signal. The second signal level indicates a different value depending on whether the target radio wave included in the received radio wave is a modulated wave or an unmodulated wave. Therefore, by using the second signal level, it is possible to determine whether the target radio wave included in the received radio wave is a modulated wave or an unmodulated wave.

[0011] Furthermore, the first signal level is affected by so-called white noise, but is little affected by whether the target radio wave included in the received radio wave is a modulated wave or an unmodulated wave. Therefore, by making a determination based on the first signal level and the second signal level, rather than only the second signal level, the influence of white noise, etc. can be suppressed when determining whether the target radio wave included in the received radio wave is a modulated wave.

[0012] Therefore, since this radar detector can determine whether the target radio wave contained in the received radio wave is a modulated wave, it can prevent mistakenly determining that the target radio wave has been received when the received radio wave contains an unmodulated wave of the same frequency as the target radio wave.

[0013] Next, the modulated wave determination unit may be configured to determine that the target radio wave is a modulated wave based on a level difference value and a determination threshold value when the level difference value is greater than the determination threshold value. The modulated wave determination unit may be configured to determine that the target radio wave is not a modulated wave based on a level difference value and a determination threshold value when the level difference value is equal to or less than the determination threshold value.

[0014] The level difference value is determined according to each of the first signal level and the second signal level, and has a characteristic that the level difference value varies depending on whether the target radio wave included in the received radio wave is a modulated wave or not, while suppressing the influence of white noise, etc.

[0015] Therefore, by using the comparison result between the level difference value and the judgment threshold value, the radar detector can suppress the influence of white noise, etc. when determining whether the target radio wave contained in the received radio wave is a modulated wave, thereby improving the judgment accuracy.

[0016] Next, the detection frequency identification unit may be configured to determine whether or not the first detection signal is a signal of the intermediate frequency while varying the second frequency from a predetermined start frequency to a predetermined end frequency, and to identify the second frequency at which the first detection signal becomes a signal of the intermediate frequency as the detection frequency.

[0017] The detection frequency identifying unit may vary the second frequency so as to increase the second frequency from a start frequency to an end frequency in the variation range, or may vary the second frequency so as to decrease the second frequency from a start frequency to an end frequency in the variation range.

[0018] The modulated wave determination unit may be configured to obtain the first signal level in either a first period or a second period. The first period may correspond to a period from when the second frequency is the start frequency to when it reaches the detection frequency. The second period may correspond to a period from when the second frequency deviates from the detection frequency to when it reaches the end frequency.

[0019] It is clear that in the first period and the second period, the second frequency is not the detection frequency, and the level of the second detection signal in the first period or the second period can be used as the first signal level.

[0020] When the first signal level is acquired in the first period, the first signal level is already acquired at the time when the second signal level is acquired. In this case, the radar detector can determine whether the target radio wave included in the received radio wave is a modulated wave immediately after acquiring the second signal level.

[0021] When the first signal level is acquired in the second period, the first signal level may be acquired after the second signal level is acquired. In an environment in which the first signal level can be acquired with less influence of noise and the like in the second period than in the first period, the first signal level may be acquired in the second period. Such a radar detector can improve the detection accuracy of the first signal level, and can thereby improve the accuracy of determining whether the target radio wave included in the received radio wave is a modulated wave.

[0022] The modulated wave determination unit may be configured to acquire at least one of the first signal level and the second signal level while the second frequency is maintained at a constant frequency, thereby making it possible to acquire at least one of the first signal level and the second signal level with higher accuracy than when the first signal level and the second signal level are acquired while the second frequency is fluctuating.

[0023] The modulated wave determination unit may be configured to acquire the second signal level while the second frequency is maintained at the detection frequency, thereby making it possible to acquire the second signal level with higher accuracy than when the period during which the second frequency is the detection frequency is short.

[0024] The modulated wave determination unit may be configured to acquire the first signal level in a state where the second frequency is maintained at a non-detection frequency that is not the detection frequency, thereby making it possible to acquire the first signal level with higher accuracy than when the first signal level is acquired in a state where the second frequency is fluctuating.

[0025] The second detection unit may be configured to obtain the second detected signal by performing envelope detection on the first detected signal. By using envelope detection, the second detected signal, which changes depending on the amplitude of the first detected signal, can be detected from the first detected signal.

[0026] The second detection unit may be configured to obtain the second detected signal by performing average value detection on the first detected signal. By using average value detection, the second detected signal that changes according to the amplitude of the first detected signal can be detected from the first detected signal.

[0027] The first signal mixing unit may be configured to be able to change the first frequency. By allowing the first signal mixing unit to change the first frequency, this radar detector can determine whether each of the multiple types of target radio waves having different frequencies is a modulated wave. In other words, this radar detector can suppress erroneous determination that a modulated wave of a target radio wave has been received when an unmodulated wave of the target radio wave is included in the received radio waves for multiple types of target radio waves.

[0028] The radar detector may include a notification unit. The notification unit may be configured to notify a user of the reception of the received radio wave including the modulated wave when the modulated wave determination unit determines that the target radio wave included in the received radio wave is a modulated wave. The radar detector can notify a user of the reception of the received radio wave including the modulated wave. [Brief description of the drawings]

[0029] [Figure 1] FIG. 2 is a block diagram showing the hardware configuration of a radar detector. [Diagram 2] 13 is a flowchart showing the contents of a K-band speed camera detection process. [Diagram 3] This is an explanatory diagram showing the waveforms of each signal when a radar detector that performs envelope detection receives K-band radio waves emitted by a K-band enforcement camera. [Figure 4] FIG. 2 is an explanatory diagram showing the waveforms of each signal when a radar detector that performs envelope detection receives K-band radio waves emitted by another device. [Diagram 5] This is an explanatory diagram showing the waveforms of each signal when a radar detector that performs average value detection receives K-band radio waves emitted by a K-band enforcement device. [Figure 6] FIG. 1 is an explanatory diagram showing the waveforms of each signal when a radar detector that performs average value detection receives K-band radio waves emitted by another device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Hereinafter, embodiments to which the present disclosure is applied will be described with reference to the drawings. It goes without saying that the present disclosure is in no way limited to the following embodiments, and various forms can be adopted as long as they fall within the technical scope of the present disclosure.

[0031] [1. First embodiment] [1-1. Overall composition] The radar detector 1 of this embodiment shown in Fig. 1 is mounted in the cabin of a vehicle such as an automobile. The radar detector 1 is configured to detect microwave radio waves emitted from a vehicle speed measurement device. The microwave radio waves emitted from the vehicle speed measurement device correspond to the target radio waves of the radar detector 1.

[0032] The vehicle speed measuring device is configured to emit radio waves to a vehicle and receive the radio waves reflected by the vehicle to measure the traveling speed of the vehicle. The vehicle speed measuring device may be fixedly installed on a road or at the side of a road, or may be portable.

[0033] The vehicle speed measuring device includes, for example, a vehicle speed measuring device that emits X-band radio waves (hereinafter also referred to as an X-band speed camera), a vehicle speed measuring device that emits K-band radio waves (hereinafter also referred to as a K-band speed camera), etc. X-band radio waves are radio waves with an X-band frequency (10.525 [GHz]). K-band radio waves are radio waves with a K-band frequency (24.100 [GHz]). K-band radio waves emitted from a K-band speed camera are radio waves modulated based on a predetermined procedure. Note that the type of modulation performed by a K-band speed camera includes frequency modulation, etc.

[0034] The radar detector 1 is configured to detect a vehicle speed measuring device (X-band or K-band enforcement camera) based on the result of determining whether or not a target radio wave (for example, an X-band radio wave or a K-band radio wave) is included in the radio wave received from outside. The radar detector 1 is also configured to determine whether the K-band radio wave included in the radio wave received from outside is a modulated K-band radio wave or an unmodulated K-band radio wave.

[0035] The radar detector 1 comprises a receiving unit 11, a first oscillator 13, a first mixer 15, an amplifier 17, a second oscillator 18, a second mixer 19, a first detection unit 21, a sweep control unit 23, a bandpass filter 27, a second detection unit 29, a main control unit 31, and an alarm unit 33.

[0036] The receiving unit 11 is configured to receive radio waves including microwaves and output the received signal Sre. The receiving unit 11 may be configured to include an antenna. The first oscillator 13 is configured to output a first frequency signal Sf1. The first frequency signal Sf1 is a signal having a first frequency Fr1.

[0037] The first oscillator 13 includes an X-band oscillator 13a and a K-band oscillator 13b. The X-band oscillator 13a is configured to output an X-band signal Sx of an X frequency Fx (=11.525 [GHz]). The K-band oscillator 13b is configured to output a K-band signal Sk of a K frequency Fk (=25.100 [GHz]). The first oscillator 13 outputs the X-band signal Sx or the K-band signal Sk as the first frequency signal Sf1.

[0038] The X frequency Fx is determined based on the X band frequency of the X band radio wave and a predetermined intermediate frequency Fm. The K frequency Fk is determined based on the K band frequency of the K band radio wave and the intermediate frequency Fm. The intermediate frequency Fm is set to, for example, 1000 [MHz]. The X frequency Fx may be 9.525 [GHz]. In this case, the K frequency Fk may be 23.100 [GHz].

[0039] The first oscillator 13 is configured to output the X band signal Sx or the K band signal Sk as the first frequency signal Sf1 in response to the frequency assignment signal Sfs received from the main control unit 31. In other words, the first oscillator 13 is configured to be able to change the first frequency Fr1 of the first frequency signal Sf1 in response to the frequency assignment signal Sfs.

[0040] The first mixer 15 is configured to mix the received signal Sre with the first frequency signal Sf1 and output the first mixed signal Sm1 obtained by mixing. The first mixer 15 frequency-converts the received signal Sre based on the first frequency Fr1 of the first frequency signal Sf1 and outputs the first mixed signal Sm1 after frequency conversion. The first mixed signal Sm1 corresponds to a signal obtained by frequency-converting the received signal Sre based on the first frequency Fr1.

[0041] The amplifier 17 is configured to amplify the first mixed signal Sm1. The second oscillator 18 is configured to output a second frequency signal Sf2. The second oscillator 18 is configured to be able to change the frequency of the second frequency signal Sf2 (hereinafter also referred to as the second frequency Fr2). The second oscillator 18 sets the second frequency Fr2 in response to a frequency control signal Sfc received from the sweep control unit 23, and outputs the second frequency signal Sf2.

[0042] The second mixer 19 is configured to mix the amplified first mixed signal Sm1 and the second frequency signal Sf2 and output the second mixed signal Sm2 obtained by mixing. The second mixer 19 frequency-converts the first mixed signal Sm1 based on the second frequency Fr2 of the second frequency signal Sf2 and outputs the second mixed signal Sm2 after frequency conversion. The second mixed signal Sm2 corresponds to a signal obtained by frequency-converting the first mixed signal Sm1 based on the second frequency Fr2.

[0043] The first detection unit 21 is configured to detect a signal of a predetermined frequency band from the second mixed signal Sm2. The first detection unit 21 is configured to output a first detection signal Sd1 obtained by detection from the second mixed signal Sm2. The "predetermined frequency band" here is a frequency band including the intermediate frequency Fm. The predetermined frequency band in the first detection unit 21 is fixed (unchanged), but the frequency of the radio wave detected as the first detection signal Sd1 can be changed by changing the first frequency Fr1 of the first frequency signal Sf1. For example, by changing the first frequency Fr1, the first detection signal Sd1 can be set to a signal corresponding to an X-band radio wave, or the first detection signal Sd1 can be set to a signal corresponding to a K-band radio wave.

[0044] The sweep control unit 23 is configured to start a sweep process of the second frequency Fr2 in response to receiving a start signal Sst from the main control unit 31. The sweep control unit 23 is configured to control the second oscillator 18 to execute a sweep process of the second frequency Fr2. The sweep process is a process of changing the second frequency Fr2. The sweep process of this embodiment is set so as to change the second frequency Fr2 from a start frequency Fr2a to an end frequency Fr2b. The sweep control unit 23 executes the sweep process of the second frequency Fr2 and determines whether or not the first detection signal Sd1 includes a signal of the intermediate frequency Fm. In other words, the sweep control unit 23 executes the sweep process of the second frequency Fr2 and determines whether or not the first detection signal Sd1 includes a signal corresponding to an X-band radio wave or a signal corresponding to a K-band radio wave.

[0045] The start frequency Fr2a and the end frequency Fr2b are set to specific values ​​so as to include the intermediate frequency Fm between the start frequency Fr2a and the end frequency Fr2b. The start frequency Fr2a and the end frequency Fr2b may be set to any appropriate value depending on conditions such as the application and the environment. For example, the start frequency Fr2a may be set to a frequency obtained by subtracting a predetermined adjustment value Fv from the intermediate frequency Fm. In this case, the end frequency Fr2b may be set to a frequency obtained by adding the adjustment value Fv to the intermediate frequency Fm. For example, the adjustment value Fv may be several tens of MHz.

[0046] When the sweep control unit 23 determines that the first detection signal Sd1 contains a signal of the intermediate frequency Fm (in other words, that the first detection signal Sd1 contains a signal corresponding to an X-band radio wave or a K-band radio wave) during the sweep process of the second frequency Fr2, the sweep control unit 23 controls the second oscillator 18 to temporarily stop the sweep process of the second frequency Fr2. After stopping the sweep process of the second frequency Fr2, the sweep control unit 23 starts measuring the elapsed time, and when a predetermined stop time Tst has elapsed, resumes the sweep process of the second frequency Fr2.

[0047] The sweep control unit 23 is configured to output an input signal Sb1 and an end signal Sb2. The sweep control unit 23 temporarily stops the sweep process of the second frequency Fr2, and outputs the input signal Sb1 when a stop time Tst has elapsed. The input signal Sb1 is a signal indicating that the sweep process of the second frequency Fr2 has resumed. In the sweep process of the second frequency Fr2, when the second frequency Fr2 reaches the end frequency Fr2b, the sweep control unit 23 outputs the end signal Sb2. The end signal Sb2 is a signal indicating that the sweep process of the second frequency Fr2 has ended.

[0048] That is, the sweep control unit 23 is configured to receive the start signal Sst and start the sweep process of the second frequency Fr2, and then, while varying the second frequency Fr2, identify the detection frequency Fde corresponding to the second frequency Fr2 when the first detection signal Sd1 contains a signal of the intermediate frequency Fm (in other words, the first detection signal Sd1 contains a signal corresponding to the X-band radio wave or the K-band radio wave). In response to the first detection signal Sd1 containing a signal corresponding to the X-band radio wave or the K-band radio wave, the sweep control unit 23 temporarily stops the sweep process of the second frequency Fr2 by maintaining the second frequency Fr2 at a constant value (here, the detection frequency Fde) for the stop time Tst. After that, the sweep control unit 23 resumes the sweep process of the second frequency Fr2 when the stop time Tst has elapsed.

[0049] For example, if the first oscillator 13 is set to output a signal of K frequency Fk, when the first detection signal Sd1 becomes a signal of intermediate frequency Fm (in other words, a signal corresponding to a K-band radio wave), the sweep control unit 23 maintains the second frequency Fr2 at a constant value for the stop time Tst, and then resumes the sweep process of the second frequency Fr2.

[0050] The bandpass filter 27 is configured to extract frequency components of a predetermined target frequency band from the first detection signal Sd1 and output the extracted signal (hereinafter, also referred to as an extracted signal Sbp). In Fig. 1, the bandpass filter 27 is written as BPF27. The "predetermined target frequency band" here is any frequency band including the intermediate frequency Fm.

[0051] The second detection unit 29 is configured to perform envelope detection on the extraction signal Sbp and output the second detection signal Sd2 obtained by the detection. The second detection unit 29 may include, for example, a diode detection circuit that performs diode detection. The second detection unit 29 may perform envelope detection on the extraction signal Sbp by performing diode detection.

[0052] The bandpass filter 27 and the second detection section 29 are configured to detect a second detection signal Sd2, which changes according to the amplitude of the first detection signal Sd1, from the first detection signal Sd1, and output the second detection signal Sd2.

[0053] The main control unit 31 is configured to control each unit provided in the radar detector 1. The main control unit 31 includes a calculation unit 31a (hereinafter also referred to as CPU 31a) and a storage unit 31b (hereinafter also referred to as MEM 31b). The MEM 31b includes a ROM, a RAM, a NVRAM, etc. (not shown). The CPU 31a is configured to execute processing in accordance with a computer program stored in the ROM. The RAM is used as a working area when the CPU 31a executes processing. The NVRAM is an electrically rewritable non-volatile memory, and stores various data referenced when the CPU 31a executes processing. The processing executed by the main control unit 31 is realized by the CPU 31a executing processing in accordance with a computer program stored in the ROM.

[0054] The main control unit 31 includes an A / D conversion unit (not shown). The A / D conversion unit is configured to convert an analog signal into a digital signal. The main control unit 31 is configured to receive the second detection signal Sd2 as an analog signal from the second detection unit 29, and perform A / D conversion using the A / D conversion unit. The main control unit 31 executes various control processes using the second detection signal Sd2 as a digital signal.

[0055] The main control unit 31 is configured to execute at least a part of the K-band speed camera detection process, which will be described later, as one of various control processes. The K-band speed camera detection process is a process that uses the second detection signal Sd2 to determine whether or not the radio waves received by the receiver 11 include K-band radio waves, and to determine whether the K-band radio waves are modulated K-band radio waves or unmodulated K-band radio waves.

[0056] The main control unit 31 is configured to output a start signal Sst to the sweep control unit 23. The start signal Sst is a command signal for notifying the sweep control unit 23 of the timing to start the sweep process of the second frequency Fr2.

[0057] The notification unit 33 is configured to notify that a vehicle speed measuring device has been detected in response to a notification command from the main control unit 31. The notification unit 33 may include an audio output unit such as a speaker and perform a notification operation by audio output of a warning sound. The notification unit 33 may include a warning light and perform a notification operation by turning on or blinking the warning light. The notification unit 33 may include an image display unit and perform a notification operation by image display of a warning image.

[0058] [1-2. Traffic camera detection process] A description will now be given of the enforcement camera detection process executed by the radar detector 1. The enforcement camera detection process is a process for detecting enforcement cameras (in other words, vehicle speed measurement devices) that enforce vehicle speed regulations using X-band radio waves or K-band radio waves.

[0059] The speed camera detection process is executed by each part of the radar detector 1 (such as the sweep control unit 23) mainly by the main control unit 31. The main control unit 31 is configured to be started up when the radar detector 1 receives power from an accessory power source (not shown) of the vehicle. In response to being started up, the main control unit 31 executes various control processes. The main control unit 31 is configured to execute at least the speed camera detection process.

[0060] The speed camera detection process includes an X-band speed camera detection process and a K-band speed camera detection process. The X-band speed camera detection process is a process for detecting an X-band speed camera that uses X-band radio waves to regulate vehicle speed. The K-band speed camera detection process is a process for detecting a K-band speed camera that uses K-band radio waves to regulate vehicle speed.

[0061] The radar detector 1 is configured to execute the speed camera detection process to alternately execute the X-band speed camera detection process and the K-band speed camera detection process twice each. In detail, the radar detector 1 repeats the process of executing the X-band speed camera detection process twice, then executing the K-band speed camera detection process twice, and then executing the X-band speed camera detection process twice again, then executing the K-band speed camera detection process twice.

[0062] Here, the K-band speed camera detection process will be described with reference to FIG. When the radar detector 1 starts the K-band speed camera detection process, first in S110 (S represents step), the K-band oscillator 13b is set to the ON state. Specifically, the main control unit 31 outputs a frequency designation signal Sfs for setting the K frequency Fk to the first oscillator 13. In response to the frequency designation signal Sfs received from the main control unit 31, the first oscillator 13 outputs the K-band signal Sk as the first frequency signal Sf1.

[0063] In S120, the radar detector 1 starts the sweep process of the second frequency Fr2. Specifically, the main control unit 31 outputs a start signal Sst to the sweep control unit 23. In response to receiving the start signal Sst, the sweep control unit 23 starts the sweep process of the second frequency Fr2. The sweep control unit 23 starts the process of changing the second frequency Fr2 from the start frequency Fr2a to the end frequency Fr2b.

[0064] In S130, the radar detector 1 detects the value of the second detection signal Sd2 and records the detected value as the first signal level Y1. Specifically, the main control unit 31 detects the digital value of the second detection signal Sd2 and records the detected value in the MEM 31b as the first signal level Y1. The first signal level Y1 corresponds to the amplitude of the second detection signal Sd2 when the second frequency Fr2 is not the detection frequency Fde.

[0065] In S140, the radar detector 1 determines whether the sweep process of the second frequency Fr2 has ended, and ends this process if the determination is affirmative, and proceeds to S150 if the determination is negative. Here, the sweep control unit 23 determines whether the second frequency Fr2 has reached the end frequency Fr2b. In response to the second frequency Fr2 reaching the end frequency Fr2b, the sweep control unit 23 determines that the sweep process of the second frequency Fr2 has ended. When the sweep control unit 23 determines that the sweep process of the second frequency Fr2 has ended, it outputs an end signal Sb2 to the main control unit 31.

[0066] In S150, the radar detector 1 determines whether or not the first detected signal Sd1 includes a K-band signal Sk, and if the determination is affirmative, the process proceeds to S160, whereas if the determination is negative, the process proceeds to S140. Here, the sweep control unit 23 determines whether or not the first detected signal Sd1 includes a signal of intermediate frequency Fm (in other words, whether or not the first detected signal Sd1 includes a signal corresponding to a K-band radio wave).

[0067] In S160, the radar detector 1 temporarily stops the sweep process of the second frequency Fr2. Here, the sweep control unit 23 controls the second oscillator 18 to maintain the second frequency Fr2 at a constant frequency, thereby temporarily stopping the sweep process of the second frequency Fr2. The second frequency Fr2 at this time corresponds to the detection frequency Fde. After stopping the sweep process of the second frequency Fr2, the sweep control unit 23 starts measuring the elapsed time.

[0068] In S170, the radar detector 1 determines whether or not a stop time Tst has elapsed after stopping the sweep process of the second frequency Fr2, and proceeds to S180 if the determination is affirmative, or proceeds to S140 if the determination is negative. Here, the sweep control unit 23 determines whether or not the stop time Tst has elapsed since the sweep process of the second frequency Fr2 was stopped.

[0069] In S180, the radar detector 1 detects the value of the second detection signal Sd2, records the detected value as the second signal level Y2, and then resumes the sweep process of the second frequency Fr2. Specifically, first, the sweep control unit 23 outputs an input signal Sb1 to the main control unit 31. In response to receiving the input signal Sb1, the main control unit 31 detects the digital value of the second detection signal Sd2, and records the detected value in the MEM 31b as the second signal level Y2. The second signal level Y2 corresponds to the amplitude of the second detection signal Sd2 when the second frequency Fr2 is the detection frequency Fde. In addition, after outputting the input signal Sb1, the sweep control unit 23 resumes the sweep process of the second frequency Fr2.

[0070] In S190, the radar detector 1 compares the level difference value Dr (=Y2-Y1) obtained by subtracting the first signal level Y1 from the second signal level Y2 with a predetermined judgment threshold α to determine whether the level difference value Dr is greater than the judgment threshold α, and if the result is positive, the process proceeds to S200, and if the result is negative, the process proceeds to S210.

[0071] Here, the main control unit 31 judges whether or not the level difference value Dr is greater than the judgment threshold value α. The judgment threshold value α is pre-recorded in the MEM 31b. The main control unit 31 reads out the second signal level Y2, the first signal level Y1, and the judgment threshold value α from the MEM 31b, and performs a comparison process between the level difference value Dr and the judgment threshold value α. The main control unit 31 makes a positive judgment when the level difference value Dr is greater than the judgment threshold value α (Y2-Y1>α), and makes a negative judgment when the level difference value Dr is equal to or less than the judgment threshold value α (Y2-Y1≦α).

[0072] In S200, the radar detector 1 determines that a K-band enforcement camera has been detected. Specifically, the main control unit 31 determines that a K-band enforcement camera present around the radar detector 1 has been detected.

[0073] In S220 following S200, the radar detector 1 executes a notification process for notifying that a K-band enforcement camera has been detected. Specifically, the main control unit 31 controls the notification unit 33, causing the notification unit 33 to execute a notification operation. Through the notification operation by the notification unit 33, the radar detector 1 notifies the user of the radar detector 1 that a K-band enforcement camera has been detected.

[0074] In S210, the radar detector 1 determines that another device other than a vehicle speed measurement device has been detected. Specifically, the main control unit 31 determines that another device other than a K-band speed sensor that emits unmodulated K-band radio waves has been detected. An example of the other device is a vending machine equipped with a human presence sensor. The human presence sensor is configured to emit unmodulated K-band radio waves.

[0075] When the radar detector 1 completes S210 or S220, the process proceeds to S140 again. After that, the radar detector 1 repeatedly executes the processes from S140 to S220 until a positive determination is made in S140. When a positive determination is made in S140, the radar detector 1 ends this process.

[0076] In this way, the radar detector 1 can detect a K-band enforcement camera by executing the K-band enforcement camera detection process and detecting modulated K-band radio waves. Since the radar detector 1 can distinguish between modulated K-band radio waves and unmodulated K-band radio waves, it is possible to suppress erroneous determination that unmodulated K-band radio waves emitted from devices other than a K-band enforcement camera are K-band radio waves from a K-band enforcement camera.

[0077] In addition, in a series of sweep processes until the second frequency Fr2 reaches the end frequency Fr2b from the start frequency Fr2a, the sweep process of the second frequency Fr2 may be temporarily stopped multiple times due to a positive determination multiple times in S150. This is considered to be caused by a false positive determination in S150 due to the influence of noise, etc. However, the radar detector 1 does not immediately determine that a K-band speed camera has been detected in response to a positive determination in S150, but determines that a K-band speed camera has been detected when a positive determination is made in S190. This allows the radar detector 1 to reduce the influence of noise, etc. when detecting a K-band speed camera.

[0078] Although detailed description of the X-band speed camera detection process is omitted, it can be realized using a known method. For example, the first oscillator 13 is set to a state in which the X-band signal Sx is output as the first frequency signal Sf1, and the main control unit 31 determines whether or not the received signal Sre contains a signal corresponding to the X-band radio wave based on the second detection signal Sd2. The main control unit 31 determines that an X-band speed camera has been detected in response to detecting the signal corresponding to the X-band radio wave.

[0079] The radar detector 1 can detect K-band speed cameras and X-band speed cameras by executing a K-band speed camera detection process and an X-band speed camera detection process, respectively. [1-3. Signal waveform] The waveforms of the signals in the radar detector 1 when the received radio waves include K-band radio waves will be described with reference to Figs.

[0080] Specifically, the difference in the waveforms of each signal when receiving K-band radio waves emitted by a K-band enforcement device and when receiving K-band radio waves emitted by other devices (for example, a human presence sensor in a vending machine) will be explained. Figure 3 shows the signal waveform when receiving K-band radio waves emitted by a K-band enforcement device, and Figure 4 shows the signal waveform when receiving K-band radio waves emitted by other devices. K-band radio waves emitted by a K-band enforcement device are modulated K-band radio waves. K-band radio waves emitted by other devices are unmodulated K-band radio waves.

[0081] 3 and 4, the radar detector 1 executes the above-mentioned K-band speed camera detection process to perform a sweep process of the second frequency signal Sf2. In the sweep process, the second frequency Fr2 of the second frequency signal Sf2 is changed from a start frequency Fr2a to an end frequency Fr2b.

[0082] Time t1 is the time when the radar detector 1 starts receiving the reception signal Sre. Time t2 is the start time of the sweep process, and time t7 is the end time of the sweep process. The sections from time t2 to time t3, from time t4 to time t5, and from time t6 to time t7 are sections in which the sweep process of the second frequency Fr2 is being executed, and the sections from time t3 to time t4, and from time t5 to time t6 are sections in which the sweep process of the second frequency Fr2 is temporarily stopped.

[0083] Among these, the first period W1 from time t2 to t3 corresponds to the period from when the second frequency Fr2 is the start frequency Fr2a to when it reaches the detection frequency Fde, and the second period W2 from time t4 to t7 corresponds to the period from when the second frequency Fr2 deviates from the detection frequency Fde to when it reaches the end frequency Fr2b.

[0084] The radar detector 1 of this embodiment acquires the first signal level Y1 in the first period W1. The radar detector 1 acquires the second signal level Y2 in the period from time t3 to t4 when the second frequency Fr2 is the detection frequency Fde.

[0085] The waveform shown in Fig. 3 is different from the waveform shown in Fig. 4 in the magnitude of the amplitude of the extraction signal Sbp and the value of the second detection signal Sd2 in the section from time t3 to time t4. Specifically, the waveform shown in Fig. 3 is different from the waveform shown in Fig. 4 in that the amplitude of the extraction signal Sbp is larger and the value of the second detection signal Sd2 is larger. Accordingly, in the waveform shown in Fig. 3, the level difference value Dr is larger than the decision threshold value α (Y2-Y1>α). In the waveform shown in Fig. 4, the level difference value Dr is equal to or smaller than the decision threshold value α (Y2-Y1≦α).

[0086] For these reasons, the radar detector 1 can distinguish between modulated K-band radio waves and unmodulated K-band radio waves based on the comparison result between the level difference value Dr and the judgment threshold value α. In other words, the radar detector 1 can distinguish between K-band radio waves emitted by a K-band enforcement device and K-band radio waves emitted by other devices.

[0087] Therefore, when detecting a K-band traffic camera, the radar detector 1 can suppress erroneous determination that another device is a K-band traffic camera. [1-4. Effects] As described above, the radar detector 1 includes the second detection unit 29, and thus can extract the second detection signal Sd2 from the first detection signal Sd1. The second signal level Y2 indicates a different value when the K-band radio wave included in the received radio wave is a modulated wave or an unmodulated wave. Therefore, by using the second signal level Y2, it can be determined whether the K-band radio wave included in the received radio wave is a modulated wave or an unmodulated wave.

[0088] Furthermore, the first signal level Y1 is affected by so-called white noise, but is little affected by whether the K-band radio waves included in the received radio waves are modulated or unmodulated. Therefore, by making a determination based on the first signal level Y1 and the second signal level Y2, rather than only the second signal level Y2, the influence of white noise, etc., can be suppressed when determining whether the K-band radio waves included in the received radio waves are modulated.

[0089] Therefore, the radar detector 1 can determine whether the K-band radio waves contained in the received radio waves are modulated waves or not, and can prevent the radar detector 1 from erroneously determining that modulated K-band radio waves have been received when unmodulated K-band radio waves are contained in the received radio waves.

[0090] Next, if the level difference value Dr is greater than the judgment threshold value α (Y2-Y1>α), the main control unit 31 determines that the K-band radio wave included in the received radio wave is a modulated wave. If the level difference value Dr is equal to or less than the judgment threshold value α (Y2-Y1≦α), the main control unit 31 determines that the K-band radio wave included in the received radio wave is not a modulated wave.

[0091] The level difference value Dr is determined according to each of the first signal level Y1 and the second signal level Y2. Therefore, the level difference value Dr has a characteristic of varying depending on whether the K-band radio wave included in the received radio wave is a modulated wave or not, while suppressing the influence of white noise and the like.

[0092] Therefore, by using the comparison result between the level difference value Dr and the judgment threshold value α, the radar detector 1 can suppress the influence of white noise, etc. when determining whether the K-band radio waves contained in the received radio waves are modulated waves, thereby improving the judgment accuracy.

[0093] Next, since the radar detector 1 acquires the first signal level Y1 in the first period W1, the first signal level Y1 has been acquired at the time of acquiring the second signal level Y2. In this case, the radar detector 1 can determine whether or not the K-band radio waves included in the received radio waves are modulated waves immediately after acquiring the second signal level Y2.

[0094] Next, the main control unit 31 is configured to acquire the second signal level Y2 in a state where the second frequency Fr2 is maintained at a constant detection frequency Fde. This allows the radar detector 1 to acquire the second signal level Y2 with higher accuracy than when the second frequency Fr2 is acquired in a fluctuating state. Furthermore, the radar detector 1 can acquire the second signal level Y2 with higher accuracy than when the period during which the second frequency Fr2 is the detection frequency Fde is short.

[0095] The second detection unit 29 is configured to perform envelope detection on the first detection signal Sd1 to obtain the second detection signal Sd2. That is, the second detection unit 29 can detect the second detection signal Sd2, which changes according to the amplitude of the first detection signal Sd1, from the first detection signal Sd1 by using envelope detection. Therefore, the radar detector 1 can detect the second detection signal Sd2 from the first detection signal Sd1 by using envelope detection.

[0096] The first oscillator 13 and the first mixer 15 are configured to be able to change the first frequency Fr1 of the first frequency signal Sf1 in response to the frequency designation signal Sfs. In other words, the radar detector 1 can determine whether or not each of the K-band radio waves and the X-band radio waves contained in the received radio waves is a modulated wave, because the first oscillator 13 and the first mixer 15 can change the first frequency Fr1. In other words, the radar detector 1 can suppress erroneous determination that a modulated wave of the first frequency has been received for multiple types of received radio waves (K-band radio waves and X-band radio waves) when the received radio waves contain unmodulated waves of the first frequency.

[0097] The radar detector 1 includes a notification unit 33. The notification unit 33 is configured to notify the user of the radar detector 1 that K-band radio waves (or X-band radio waves) including modulated waves have been received in response to the main control unit 31 determining that the K-band radio waves (or X-band radio waves) included in the received radio waves are modulated waves. Thus, the radar detector 1 can notify the user of the radar detector 1 that K-band radio waves (or X-band radio waves) including modulated waves have been received.

[0098] [1-5. Correspondence of Wording] Here, the correspondence between the words will be described. The first oscillator 13 and the first mixer 15 correspond to an example of a first signal mixer in the present disclosure. The second oscillator 18 and the second mixer 19 correspond to an example of a second signal mixer in the present disclosure. The sweep control unit 23 corresponds to an example of a detection frequency identifying unit in the present disclosure. The main control unit 31 corresponds to an example of a modulated wave determining unit in the present disclosure.

[0099] 2. Other embodiments Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and can be embodied in various forms without departing from the gist of the present disclosure.

[0100] (a) In the above embodiment, a radar detector 1 is described that is configured to alternately execute the X-band speed camera detection process and the K-band speed camera detection process two times each. However, the radar detector of the present disclosure is not limited to such a configuration.

[0101] For example, the radar detector may be configured to alternately execute the X-band camera detection process and the K-band camera detection process once each, or to alternately execute the X-band camera detection process and the K-band camera detection process three or more times.

[0102] (b) In the above embodiment, a radar detector that detects X-band radio waves and K-band radio waves was described. However, the frequencies of the radio waves to be detected are not limited to the above frequencies and may be any frequency.

[0103] Although the above-mentioned radar detector is configured to detect two types of radio waves with different frequencies, it may be configured to detect three or more types of radio waves with different frequencies. For example, the first oscillator 13 may be configured to output one of three or more types of frequency signals with different frequencies as the first frequency signal Sf1.

[0104] (c) In the above embodiment, a radar detector has been described in which, in the sweep process of the second frequency Fr2, the second frequency Fr2 is increased from the start frequency to the end frequency as shown in Fig. 3 and Fig. 4, but the radar detector of the present disclosure is not limited to this configuration. For example, the radar detector of the present disclosure may be configured to decrease the second frequency Fr2 from the start frequency to the end frequency in the sweep process of the second frequency Fr2.

[0105] (d) In the above embodiment, the radar detector of the present disclosure is described as acquiring the first signal level Y1 in the first period W1, but the radar detector of the present disclosure is not limited to this. For example, the radar detector of the present disclosure may acquire the first signal level Y1 in the second period W2. When acquiring the first signal level Y1 in the second period W2, the radar detector may acquire the first signal level Y1 after acquiring the second signal level Y2.

[0106] For example, in an environment where the first signal level Y1 can be acquired with less influence of noise and the like in the second period W2 than in the first period W1, the first signal level Y1 may be acquired in the second period W2. Such a radar detector can improve the detection accuracy of the first signal level Y1, and can therefore improve the accuracy of determining whether a target radio wave (e.g., K-band radio wave, X-band radio wave, etc.) included in the received radio wave is a modulated wave.

[0107] (e) In the above embodiment, a configuration was described in which the first signal level Y1 is acquired while the second frequency Fr2 is changing, and the second signal level Y2 is acquired while the second frequency Fr2 is maintained at a constant frequency, but the radar detector of the present disclosure is not limited to such a configuration.

[0108] For example, the radar detector of the present disclosure may be configured to acquire the first signal level Y1 while the second frequency Fr2 is maintained at a constant frequency. The radar detector of the present disclosure may be configured to acquire the first signal level Y1 while the second frequency Fr2 is maintained at a constant frequency (hereinafter also referred to as the non-detection frequency Fun), and acquire the second signal level Y2 while the second frequency Fr2 is maintained at a constant frequency (in other words, the detection frequency Fde). The non-detection frequency Fun is a frequency different from the detection frequency Fde.

[0109] As a result, the radar detector disclosed herein can acquire the first signal level and the second signal level with greater accuracy than when acquiring the first signal level and the second signal level in a state in which the second frequency is fluctuating.

[0110] (f) In the above embodiment, the second detection unit 29 detects the second detection signal Sd2 by envelope detection, but the radar detector of the present disclosure is not limited to this configuration. For example, the second detection unit may be configured to obtain the second detection signal Sd2 by average value detection. By using average value detection, the second detection signal Sd2, which changes according to the amplitude of the first detection signal Sd1, can be detected from the first detection signal Sd1.

[0111] Here, the second detected signal Sd2 obtained by average detection from the same extracted signal Sbp as the extracted signal Sbp shown in Figures 3 and 4 is shown in Figures 5 and 6. The second detected signal Sd2 obtained by average detection (Figures 5 and 6) does not have a completely identical waveform when compared with the second detected signal Sd2 obtained by envelope detection (Figures 3 and 4), but shows a waveform with a similar changing state.

[0112] That is, the level difference value Dr (=Y2-Y1) obtained using the second detection signal Sd2 obtained by average detection is different when receiving a K-band radio wave emitted by a K-band enforcement device (FIG. 5) from when receiving a K-band radio wave emitted by another device (e.g., a human presence sensor in a vending machine) (FIG. 6). Specifically, in the waveform shown in FIG. 5, the level difference value Dr is greater than the judgment threshold value α (Y2-Y1>α). In the waveform shown in FIG. 6, the level difference value Dr is equal to or less than the judgment threshold value α (Y2-Y1≦α).

[0113] For this reason, even if the radar detector is configured to obtain the second detection signal Sd2 by average value detection, it can distinguish between modulated K-band radio waves and unmodulated K-band radio waves based on the comparison result between the level difference value Dr and the judgment threshold value α. In other words, even if the radar detector is configured to obtain the second detection signal Sd2 by average value detection, it can distinguish between K-band radio waves emitted by a K-band enforcement device and K-band radio waves emitted by other devices.

[0114] Therefore, even if the radar detector is configured to obtain the second detection signal Sd2 by average value detection, when detecting a K-band enforcement camera, it is possible to prevent the radar detector from erroneously determining that another device is a K-band enforcement camera.

[0115] (g) The function of one component in the above embodiments may be distributed as multiple components, or the functions of multiple components may be integrated into one component. At least a part of the configuration of the above embodiments may be replaced with a known configuration having a similar function. A part of the configuration of the above embodiments may be omitted. At least a part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. Any aspect included in the technical idea identified only by the wording described in the claims is an embodiment of the present disclosure. [Explanation of symbols]

[0116] 1...radar detector, 11...receiving unit, 13...first oscillator, 13a...X-band oscillator, 13b...K-band oscillator, 15...first mixer, 17...amplifier, 18...second oscillator, 19...second mixer, 21...first detection unit, 23...sweep control unit, 27...bandpass filter (BPF), 29...second detection unit, 31...main control unit, 31a...calculation unit (CPU), 31b...memory unit, 33...alarm unit.

Claims

1. A receiving unit configured to receive a reception radio wave including a target radio wave and output the reception signal as a reception signal; a first signal mixing unit configured to output a first mixed signal obtained by mixing the received signal with a signal of a first frequency, the first frequency being determined according to a frequency of the target radio wave; a second signal mixing unit configured to output a second mixed signal obtained by mixing a signal of a second frequency with the first mixed signal and to change the second frequency; a first detection unit configured to detect a signal of a predetermined frequency band including a predetermined intermediate frequency from the second mixed signal and output a first detection signal obtained by the detection; a detection frequency specifying unit configured to control the second signal mixing unit to change the second frequency and to specify a detection frequency corresponding to the second frequency when the first detection signal becomes a signal of the intermediate frequency; a second detection unit configured to detect a second detection signal, the second detection signal changing depending on an amplitude of the first detection signal, from the first detection signal and output the second detection signal; a modulated wave determination unit configured to determine whether or not the target radio wave included in the received radio wave is a specific modulated wave based on a first signal level corresponding to an amplitude of the second detection signal when the second frequency is not the detection frequency and a second signal level corresponding to an amplitude of the second detection signal when the second frequency is the detection frequency; Equipped with The specific modulated wave is a frequency-modulated modulated wave, and the second signal level is higher than the first signal level. Radar detector.

2. 2. The radar detector according to claim 1, the modulated wave determination unit is configured to determine, based on a level difference value obtained by subtracting the first signal level from the second signal level and a predetermined determination threshold, that the target radio wave is the specific modulated wave when the level difference value is greater than the determination threshold, and to determine that the target radio wave is not the specific modulated wave when the level difference value is equal to or less than the determination threshold. Radar detector.

3. The radar detector according to claim 1 or 2, the detection frequency identification unit is configured to determine whether or not the first detection signal is a signal of the intermediate frequency while varying the second frequency from a predetermined start frequency to a predetermined end frequency, and to identify, as the detection frequency, the second frequency at which the first detection signal becomes a signal of the intermediate frequency. Radar detector.

4. 4. The radar detector according to claim 3, the modulated wave determination unit is configured to acquire the first signal level in either a first period or a second period, the first period corresponding to a period from when the second frequency is the start frequency to when it reaches the detection frequency, and the second period corresponding to a period from when the second frequency deviates from the detection frequency to when it reaches the end frequency. Radar detector.

5. A radar detector according to any one of claims 1 to 4, the modulated wave determination unit is configured to acquire at least one of the first signal level and the second signal level in a state in which the second frequency is maintained at a constant frequency. Radar detector.

6. 6. The radar detector according to claim 5, the modulated wave determination unit is configured to acquire the second signal level in a state in which the second frequency is maintained at the detection frequency. Radar detector.

7. The radar detector according to claim 5 or 6, the modulated wave determination unit is configured to acquire the first signal level in a state in which the second frequency is maintained at a non-detection frequency that is not the detection frequency. Radar detector.

8. A radar detector according to any one of claims 1 to 7, The second detection unit is configured to perform envelope detection on the first detection signal to obtain the second detection signal. Radar detector.

9. A radar detector according to any one of claims 1 to 7, The second detection unit is configured to perform average value detection on the first detection signal to obtain the second detection signal. Radar detector.

10. A radar detector according to any one of claims 1 to 9, The first signal mixing unit is configured to be able to change the first frequency. Radar detector.

11. A radar detector according to any one of claims 1 to 10, a notification unit configured to notify that the received radio wave including the specific modulated wave has been received in response to the determination by the modulated wave determination unit that the target radio wave included in the received radio wave is the specific modulated wave, Radar detector.

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