Portable radar transponder tester and test method

Abstract

The invention discloses a portable radar transponder tester and a test method, comprising: a transmitting unit: used for generating a simulated radar signal to trigger the radar transponder to work; a receiving unit: used for receiving a response signal of a detected radar transponder, wherein the response signal has the same frequency as a signal transmitted by the transmitting unit, and mixing and amplifying the response signal; an intermediate frequency unit: used for receiving the intermediate frequency signal after mixing and amplification, wherein the intermediate frequency signal is converted into an amplitude component and a frequency component, and the amplitude component is amplitude modulated and demodulated to obtain a signal envelope; a digital signal processing unit and a main control unit. The whole instrument is small and can be conveniently carried for on-site testing, and integrates multiple functions in one, so as to solve the testing problem on-site in real time.

Description

Technical Field

[0001] The invention relates to the field of communication and navigation, and in particular to a portable radar transponder tester and a test method. Background Art

[0002] A radar transponder is a navigation device that emits a specific coded signal after receiving a radar signal. It is mainly used for channel navigation and key area identification. A radar transponder can be regarded as a passive radar. By receiving the signal from the ship's radar, the radar transponder immediately emits a response signal after receiving the signal, so that nearby ships can accurately detect the target and correctly guide the ship's navigation. Radar transponder detection generally has the following problems:

[0003] The detection of radar transponders requires special environment and equipment.

[0004] Currently, on-site inspections are limited to partial qualitative testing by vessels equipped with radar, which gradually change distances.

[0005] Reading Morse code from radar charts is relatively complicated and difficult, and requires a certain level of radio expertise.

[0006] On-site testing is based solely on the sound of the radar transponder's self-test. Radar transponders without self-test functions cannot be tested on-site. In actual work, even if the self-test passes, there are cases where the system does not work properly.

[0007] There have been no professional instruments and equipment for detecting radar transponders either internationally or domestically.

[0008] The detection of radar transponders requires special environment and equipment. It can only be carried out in the laboratory with complex equipment. In addition, the equipment is expensive and has high requirements for operators, and the environment must be laboratory-based. Summary of the invention

[0009] In order to overcome the shortcomings and deficiencies of the prior art, the present invention provides a portable radar transponder tester and a testing method. The entire instrument is compact and can be conveniently carried for on-site testing. It integrates multiple functions in one and can solve testing problems on-site in real time.

[0010] The present invention adopts the following technical solution:

[0011] A portable radar transponder tester, comprising:

[0012] Transmitter unit: used to generate simulated radar signals to trigger the radar transponder to work;

[0013] Receiving unit: used to receive the response signal of the detected radar transponder, whose response signal has the same frequency as the transmitting signal of the transmitting unit, and performs mixing and amplification;

[0014] Intermediate frequency unit: used to receive the intermediate frequency signal after mixing and amplification, convert the intermediate frequency signal into amplitude component and frequency component, and demodulate the amplitude component to obtain the signal envelope;

[0015] Digital signal processing unit: connected to the intermediate frequency unit and the transmitting unit respectively; used to receive corresponding signals, the corresponding signals including the frequency component and amplitude component of the intermediate frequency unit, and the transmission intensity signal of the transmitting unit;

[0016] Main control unit: connected with the digital signal processing unit, receiving unit, intermediate frequency unit and transmitting unit respectively, and obtains the sensitivity value, agile frequency, Morse code, transmission power and working bandwidth of the radar transponder to be detected by acquiring the data signal.

[0017] Further, the transmitting unit comprises:

[0018] Microwave signal generator: uses a fractional frequency phase-locked loop circuit with VCO, and the frequency reference source uses a temperature-compensated crystal oscillator;

[0019] The output microwave signal is filtered out of harmonics by a filter and then amplified by a gain amplifier. One path of the amplified signal is divided by a frequency divider to obtain a square wave signal that is input into the main control unit to detect the frequency. The other path is switched by a signal switch. A switching signal is input into a power amplifier circuit and a digitally controlled attenuation circuit, and is transmitted to the radar transponder under test through a transmitting antenna.

[0020] Further, the receiving unit includes:

[0021] Under the control of the main control unit, receiving the response signal of the radar transponder under test and the internal calibration signal;

[0022] The signal undergoes power detection. When the signal is very strong, the switching signal is directly connected to the mixer for mixing to obtain an intermediate frequency signal. When the signal is small, it is amplified by a low-noise amplifier and then added to the mixing circuit.

[0023] Furthermore, the intermediate frequency unit includes:

[0024] The input intermediate frequency signal is filtered, one path is amplified by a logarithmic amplifier, and signal strength detection is performed. The strength detection includes power component and amplitude component. The power component is input into the digital signal processing unit, and the signal envelope is obtained through the amplitude component and input into the main control unit; the other path is amplified by the amplifier, and the input frequency voltage is converted into voltage and input into the digital signal processing unit.

[0025] Furthermore, the digital signal processing unit includes four ADC sampling circuits.

[0026] Furthermore, the transmitting unit also outputs an internal calibration signal, and the internal calibration signal is input into the receiving unit, and then processed by the receiving unit and input into the digital processing unit.

[0027] Furthermore, the transmitting unit also includes a signal switch switching, and the signal after being amplified by the gain amplifier is switched by the other signal switch. One switching signal inputs the power amplifier circuit and the digital controlled attenuation circuit, and the other switching signal outputs the internal calibration signal through the digital attenuation circuit.

[0028] A testing method for a portable radar transponder tester, comprising:

[0029] The user sets the detection criteria, which include detection frequency, bandwidth and sensitivity;

[0030] Transmitting a simulated radar signal within a frequency bandwidth to trigger the transponder to respond and send a reply signal;

[0031] After receiving the response signal, it is mixed and cut into amplitude component and frequency component;

[0032] The signal envelope is obtained according to the amplitude component, and the Morse code is further obtained;

[0033] Obtaining voltage based on frequency components;

[0034] Adjust the signal strength according to the step value, repeat the above steps, and obtain the detection value of the radar transponder under test.

[0035] Further, the specific process of obtaining the detection value of the radar transponder under test is as follows:

[0036] According to the step value, lower the signal transmission strength until there is no response. The lowest signal strength that can trigger the transponder is the sensitivity of the radar transponder under test.

[0037] If the response signal of the radar transponder under test is obtained at any frequency point within the frequency bandwidth, the radar transponder meets the frequency response requirements;

[0038] If the radar transponder tunes its response frequency to be consistent with the receiving frequency according to the frequency of the received transmission signal, it has the function of agile frequency conversion.

[0039] further,

[0040] The transmitting power of the radar transponder is further calculated based on the received reply radio frequency signal strength;

[0041] The effective range of the radar transponder is calculated based on the transmitting power of the radar transponder and the receiving sensitivity of the conventional radar.

[0042] Beneficial effects of the present invention:

[0043] The instrument of the present invention is portable and can be used to perform on-site testing on a radar transponder, thereby realizing the measurement of radar transponder sensitivity, agile frequency, response bandwidth, transmission power and Morse code. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the structure of the present invention;

[0045] Figure 2 yes Figure 1 The schematic diagram of the structure of the transmitting unit;

[0046] Figure 3 yes Figure 1 A schematic diagram of the structure of the receiving unit;

[0047] Figure 4 yes Figure 1 Schematic diagram of the structure of the intermediate frequency unit;

[0048] Figure 5 yes Figure 1 A schematic diagram of the structure of the digital signal processing unit;

[0049] Figure 6 yes Figure 1 The structural diagram of the main control unit;

[0050] Figure 7 It is a schematic diagram of the process of the detection method of the present invention. DETAILED DESCRIPTION

[0051] The present invention will be further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0052] Example

[0053] like Figure 1 As shown, a portable radar transponder tester includes the following hardware devices:

[0054] Transmitter unit: used to simulate radar signals and trigger radar transponders to work. The lower end of the working frequency band is lower than the lower limit of the radar frequency band, and the higher end is higher than the upper limit of the radar frequency band, detecting the response frequency range of the radar transponder. The output signal strength of the transmitter unit is adjustable, which is used to detect the sensitivity test of the radar transponder.

[0055] Specific structure such as Figure 2 As shown,

[0056] The microwave signal generator uses a fractional frequency phase-locked loop circuit with VCO, and the frequency reference source uses a temperature-compensated crystal oscillator. Its output signal is filtered by a filter to remove harmonics, and then amplified by a gain amplifier. One signal is divided by a frequency divider to obtain a square wave signal after division, which is sent to the main control unit to detect the frequency. The other signal is switched by a signal switch. The control signal is controlled by the main control unit. When the signal switch is switched upward, the signal is input into the power amplifier circuit and the digital control attenuation circuit, and then transmitted to the radar transponder under test through the transmitting antenna of the transmitting unit. When the signal switch is switched downward, the signal is input into the digital control attenuation circuit to output the internal calibration signal. The signal strength of the transmission or calibration is all strength-detected, and the ADC is sampled and quantized into a digital signal and sent to the digital signal processing unit for processing.

[0057] Furthermore, through the combination of the two-stage cascaded digital attenuation circuit and the power amplifier circuit, different output powers can be generated to stimulate the response of the tested radar transponder, thereby testing the sensitivity of the radar transponder.

[0058] By varying the combination of frequency and amplitude, the frequency response curve of the radar transponder can be tested.

[0059] In this embodiment, the power amplifier circuit has an output RSSI strength indicator, which can accurately obtain the excitation power through ADC sampling, detection and calibration. The frequency of the signal is set by the main control MCU, and its frequency stability is guaranteed by the voltage-controlled temperature-compensated crystal oscillator.

[0060] The receiving unit is used to receive the internal calibration signal of the transmitting unit and the response signal of the detected radar transponder. The response signal has the same frequency as the transmitting signal of the transmitting unit. The specific structure is as follows: Figure 3 shown.

[0061] The switch signal is used to switch the internal calibration signal received from the antenna or the transmitting unit. Any signal is power-detected, and the switching signal is directly connected to the mixer for mixing to obtain the intermediate frequency signal. When the signal is small, it is amplified by a low-noise amplifier and then added to the mixer to be converted into an intermediate frequency signal.

[0062] Since the transmission signal of the transmitting unit has a strength and frequency known to the user, this signal is loaded into the receiving unit, thereby correcting the data at the receiving end through the known data, which is the role of the calibration signal.

[0063] Furthermore, the transmitting antenna and the receiving antenna in this embodiment are both microstrip antenna arrays, specifically a 4X4 microstrip antenna array.

[0064] Intermediate frequency unit, such as Figure 4As shown, the intermediate frequency signal is input to the filter for filtering to remove other interference signals. One path is amplified by the logarithmic amplifier, and then the signal strength detection is performed. The strength detection includes power component and amplitude component. After quantization conversion, the power component is input to the digital signal processing unit through the ADC, and the amplitude component is converted to obtain the signal envelope and input to the main control unit. The other path is amplified by the amplifier, and then the frequency voltage conversion circuit changes the frequency into voltage. This voltage represents the frequency signal. After digital conversion, it is input to the digital signal processing unit through the ADC sampling circuit.

[0065] The envelope signal is the Morse code modulated by the radar transponder response. The envelope signal is sent to the main control unit and decoded to obtain the Morse code value.

[0066] Digital signal processing unit: includes data processing calculation and generation of clock and control signals.

[0067] Under the coordinated control of the main control unit, the amplitude of the transmitted signal, the frequency and amplitude data of the intermediate frequency unit are received. These data are raw data and vary according to different devices.

[0068] When the test equipment is turned on, the digital signal processing unit will calibrate the calibration signal strength and frequency, and use the calibrated strength and frequency signals to calibrate the received signal to obtain the amplitude and voltage correspondence table and the frequency and voltage correspondence table. Based on this relationship table, the subsequent detection results are calculated.

[0069] The data signal processing unit receives the frequency and amplitude data of the intermediate frequency unit, obtains the amplitude and voltage correspondence of the received signal, and the frequency domain voltage correspondence table, and obtains the test result output by comparing with the calibration relationship table, thereby realizing result calibration, equipment self-test and calibration, and output of test results.

[0070] like Figure 5 As shown, the digital signal processing unit controls four ADC sampling circuits, which are respectively used to receive the emission intensity data of the emission unit, the calibration signal intensity data, and the field intensity and frequency data of the intermediate frequency unit.

[0071] Since the received and sent signals are all pulse signals, synchronous sampling is required, otherwise it is easy to collect useless data. Therefore, the data signal processing unit will remove the front source and the back source of the collected pulse signal and intercept the average value of the intermediate signal.

[0072] Furthermore, the ADC sampling circuit in this embodiment performs high-speed (40MHz sampling rate) sampling processing after differential amplification of the signal. This circuit is also applied to output signal strength sampling, received signal strength sampling, and received phase sampling (for receiving frequency calculation).

[0073] Main control unit: used to connect with the digital signal processing unit, receiving unit, intermediate frequency unit and transmitting unit respectively, and obtain the sensitivity value, agile frequency measurement, Morse code, transmission power and effective range of the radar transponder to be detected by acquiring data signals.

[0074] like Figure 6 As shown, the main control unit implements the following control:

[0075] Transmitter unit control: Control the transmitting frequency, transmission intensity, and internal calibration signal intensity of the transmitting unit. Receive the transmission frequency division signal and detect the transmission frequency. Control signal transmission or calibration.

[0076] Receiving unit control: Control the receiving unit local oscillator frequency and obtain the receiving power signal.

[0077] IF unit control: obtain field strength pulse envelope signal and demodulate Morse code.

[0078] Human-computer interaction: Display and set the detection content. Operate the equipment to run.

[0079] Network connection: Connect to the professional operation system through the network to transmit on-site inspection data and update operation records.

[0080] Working voltage environment detection: Due to the high frequency of the system, effective detection needs to be carried out in a suitable environment. The detection unit is in an internal sealed state and operates in a relative temperature environment filled with nitrogen. Therefore, environmental detection is very necessary. The detected data includes voltage, current of each module, temperature, pressure and humidity, etc.

[0081] In this embodiment, WiFi and Bluetooth are used to connect the various units, and no wired connection is provided to the user, thereby avoiding the generation of crosstalk.

[0082] Each unit circuit is separated by a shielding cavity. To avoid mutual interference between unit circuits, each unit circuit is designed in a different shielding cavity to improve the detection accuracy of the instrument, avoid harassment, and resist external interference.

[0083] Each power supply of each unit circuit is equipped with a filter circuit to remove the crosstalk introduced by the power supply.

[0084] Each power supply circuit outputs a 6V main power supply voltage from a low-noise switching voltage regulator circuit, which then generates an analog power supply for each circuit through low-noise linear voltage regulation. The digital power supply is generated by a step-down switching voltage regulator circuit.

[0085] The specific detection process of the present invention is as follows:

[0086] Power-on calibration process:

[0087] The frequency scanning step value and amplitude scanning step value are set by the user; the transmitting unit sends a starting scanning amplitude, and the frequency is scanned from the actual scanning frequency to the high end according to the step value, so that a frequency response characteristic of a set of known amplitude values ​​of the receiving unit is obtained, and then the amplitude is adjusted according to the amplitude step value to perform frequency scanning; thus, the corresponding relationship between the frequency, amplitude and detection value is obtained by scanning to the maximum amplitude, and accurate detection results can be obtained through fitting and interpolation compensation of the response curve of the radar transponder during the detection process.

[0088] Testing process:

[0089] The user sets the detection criteria, which include detection frequency, bandwidth and sensitivity;

[0090] Transmitting a simulated radar signal within a frequency bandwidth to trigger the transponder to respond and send a reply signal;

[0091] After receiving the response signal, it is mixed and cut into amplitude component and frequency component;

[0092] The signal envelope is obtained according to the amplitude component, and the Morse code is further obtained;

[0093] Obtaining voltage based on frequency components;

[0094] Adjust the signal strength according to the step value, repeat the above steps, and obtain the detection value of the radar transponder under test.

[0095] Adjust the system output amplitude to the sensitivity value that the transponder under test receives, and change the frequency; if the test results can accurately receive the response information, and the response code meets the setting; the equipment inspection is qualified. If no response information is received from individual frequency points, increase the amplitude value until all frequency points receive the response information. The value at this time is the detected sensitivity value.

[0096] Technical parameters determination:

[0097] Agile frequency measurement:

[0098] Change the frequency. If the corresponding signal also changes with the same frequency, it is determined that the radar transponder under test has agile frequency characteristics.

[0099] Response frequency range measurement: Determine whether the device can respond within the specified frequency range.

[0100] Minimum sensitivity measurement:

[0101] The transmission amplitude is continuously adjusted downward according to the step value set by the user until the radar transponder fails to respond. At this time, the previous amplitude is the minimum sensitivity.

[0102] Measurement of Morse Code:

[0103] The signal envelope is obtained based on the amplitude component to obtain the Morse code.

[0104] Transmit power measurement

[0105] Select a higher amplitude, start the measurement, and the transponder output power will be displayed after receiving the response packet.

[0106] The performance test indicators of the present invention are exemplified as follows:

[0107] Detection frequency and transmission frequency range: 9300MHz~9500MHz;

[0108] Sensitivity detection range: -10dB~-55dB;

[0109] The detection range of reply transmission power is 100mW~20W;

[0110] Detection distance (distance between detector and transponder) 0.5m~2m;

[0111] Morse code analysis range: All code values ​​suitable for radar transponders can be analyzed.

[0112] The detection process of this embodiment is as follows:

[0113] When starting operation, the system is first initialized to ensure the system operating environment and detection parameter settings; the system automatically detects the working conditions, power supply conditions, operating environment, etc. of each part of the system; the system is calibrated through internal standard signals to obtain a series of correction parameters for system detection, so that the system detection results accurately meet the system design requirements; according to the set detection parameters, the sample target is fully tested to obtain the detection data, and the detection results are calculated through the calibration data and the set detection parameters, and the detection results are displayed to determine whether it is a qualified product.

[0114] During the whole testing process, the ambient temperature is tested. If the temperature change exceeds the calibration temperature by 3°C, the system will automatically recalibrate to ensure the accuracy of the test results.

[0115] like Figure 7 As shown, the specific detection steps are as follows:

[0116] The transmitting unit transmits a radar simulation signal to trigger the transponder to respond.

[0117] The transponder receives the radar wave and determines its intensity;

[0118] (Optional) Tune your own answering frequency to match the receiving frequency.

[0119] When the set intensity is reached, the response is triggered and the set Morse code is transmitted as an amplitude modulated response signal.

[0120] The receiving unit receives the response signal and collects the signal strength and signal frequency.

[0121] The Morse code is parsed based on the received strength envelope.

[0122] The emission intensity starts from the minimum and gradually increases. The emission intensity when a response occurs can be used to calculate the response sensitivity.

[0123] Increase the transmit power by 3dB, and gradually change the frequency to test the response frequency bandwidth. Start from the low end of the frequency and gradually increase the transmit frequency. The frequency point where the response appears first is the low end starting point of the frequency response. Conversely, start from the highest point of the frequency band and gradually reduce the frequency. The frequency point where the response appears first is the high end point of the frequency response bandwidth. The response frequency range is between these two frequency points.

[0124] While testing the bandwidth, it is possible to determine whether the transponder has the agile frequency capability based on the transmitting frequency and the receiving end response frequency.

[0125] Calculate the transmit power based on the received RF strength and test distance.

[0126] Transmit power = response intermediate frequency signal strength - intermediate frequency gain - mixing gain - high frequency gain - receiving antenna gain + spatial attenuation.

[0127] The operating range is calculated based on the transmit power and minimum sensitivity.

[0128] Transmit power - receiving antenna gain = maximum spatial attenuation, and the distance is obtained from the relationship between spatial attenuation and distance.

[0129] According to the setting criteria or the device setting parameters obtained from the system through the network, the results are compared to determine whether the device is qualified.

[0130] The qualification is determined by the user settings or the settings in the management system.

[0131] The test process of this tester is external detection. The index characteristics of the equipment are reflected in the response signal of the radar transponder. Any tested equipment can be tested as long as it responds after receiving the radar scanning signal. The detection range includes ship distress lifesaving radar transponders and radar transmitters with sufficient gain in close-range channels.

[0132] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A portable radar transponder tester, characterized in that: include: Transmitter unit: used to generate simulated radar signals to trigger the radar transponder to work; Receiving unit: used to receive the response signal of the detected radar transponder, whose response signal has the same frequency as the transmitting signal of the transmitting unit, and performs mixing and amplification; Intermediate frequency unit: used to receive the intermediate frequency signal after mixing and amplification, convert the intermediate frequency signal into amplitude component and frequency component, and demodulate the amplitude component to obtain the signal envelope; Digital signal processing unit: connected to the intermediate frequency unit and the transmitting unit respectively; used to receive corresponding signals, the corresponding signals including the frequency component and amplitude component of the intermediate frequency unit, and the transmission intensity signal of the transmitting unit; Main control unit: connected with the digital signal processing unit, receiving unit, intermediate frequency unit and transmitting unit respectively, and obtains the sensitivity value, agile frequency, Morse code, transmission power and working bandwidth of the radar transponder to be detected by acquiring the data signal; The transmitting unit comprises: Microwave signal generator: uses a fractional frequency phase-locked loop circuit with VCO, and the frequency reference source uses a temperature-compensated crystal oscillator; The output microwave signal is filtered out of harmonics by a filter, and then amplified by a gain amplifier. One path of the amplified signal is divided by a frequency divider to obtain a square wave signal that is input into the main control unit to detect the frequency. The other path is switched by a signal switch. One switching signal is input into a power amplifier circuit and a digital control attenuation circuit, and then transmitted to the radar transponder under test through a transmitting antenna. The receiving unit comprises: Under the control of the main control unit, receiving the response signal of the radar transponder under test and the internal calibration signal; The signal undergoes power detection. When the signal is very strong, the switching signal is directly connected to the mixer for mixing to obtain an intermediate frequency signal. When the signal is small, it is amplified by a low-noise amplifier and then added to the mixing circuit. The intermediate frequency unit comprises: The input intermediate frequency signal is filtered by a filter, one path is amplified by a logarithmic amplifier, and the signal strength detection is performed. The strength detection includes a power component and an amplitude component. The power component is input to a digital signal processing unit, and a signal envelope is obtained through the amplitude component and input to a main control unit; the other path is amplified by an amplifier, and the input frequency voltage is converted into a voltage and input to a digital signal processing unit; The transmitting unit, the receiving unit, the intermediate frequency unit, the digital signal processing unit and the main control unit are separated by a shielding cavity.

2. The portable radar transponder tester according to claim 1, characterized in that: The digital signal processing unit includes four ADC sampling circuits.

3. The portable radar transponder tester according to any one of claims 1 to 2, characterized in that: The transmitting unit also outputs an internal calibration signal, which is input into the receiving unit, processed by the receiving unit and then input into the digital processing unit.

4. The portable radar transponder tester according to claim 3, characterized in that: The transmitting unit also includes a signal switch switching, and the signal after being amplified by the gain amplifier is switched by the other signal switch. One switching signal inputs the power amplifier circuit and the digital controlled attenuation circuit, and the other switching signal outputs the internal calibration signal through the digital attenuation circuit.

5. A testing method based on the portable radar transponder tester according to any one of claims 1 to 4, characterized in that: include: The user sets the detection criteria, which include detection frequency, bandwidth and sensitivity; Transmitting a simulated radar signal within a frequency bandwidth to trigger the transponder to respond and send a reply signal; After receiving the response signal, it is mixed and cut into amplitude component and frequency component; The signal envelope is obtained according to the amplitude component, and the Morse code is further obtained; Obtaining voltage based on frequency components; Adjust the signal strength according to the step value, repeat the above steps, and obtain the detection value of the radar transponder under test.

6. The testing method according to claim 5, characterized in that: According to the step value, lower the signal transmission strength until there is no response. The lowest signal strength that can trigger the transponder is the sensitivity of the radar transponder under test. If the response signal of the radar transponder under test is obtained at any frequency point within the frequency bandwidth, the radar transponder meets the frequency response requirements; If the radar transponder tunes its response frequency to be consistent with the receiving frequency according to the frequency of the received transmission signal, it has the function of agile frequency conversion.

7. The testing method according to claim 5, characterized in that: The transmitting power of the radar transponder is further calculated based on the received reply radio frequency signal strength; The effective range of the radar transponder is calculated based on the transmitting power of the radar transponder and the receiving sensitivity of the conventional radar.

Images