Radar test system

Abstract

To provide a radar test system capable of appropriately simulating even a radar (for example, a weather radar) that observes a target whose Doppler velocity of clouds, precipitation or the like fluctuates.SOLUTION: A radar test system includes: a receiving circuit that receives a signal from a test subject; a delay circuit that creates a fixed time delay in transmission without changing a waveform of an input signal; a fluctuation component injection circuit that generates a simulated target by injecting an average Doppler and a standard deviation of Doppler velocity as Doppler drift components into the input signal; a transmitting circuit that converts the input signal into a radio wave that can be transmitted; and a display control unit that controls a signal or the like generated and processed by the delay circuit and the fluctuation component injection circuit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a radar test system, and more particularly to a weather radar test system for verifying the correctness of a radar reflectivity factor and Doppler velocity of a weather radar, and the variance (deviation) of a target echo of a cloud or the like and the Doppler velocity. [Background technology]

[0002] Conventional radar test systems or target simulators have been designed for "hard targets" such as automotive radars and aircraft radars, where the term "hard target" refers to a target that has no Doppler spread or standard deviation of the echo.

[0003] For example, Patent Document 1 discloses a radar testing device that performs time domain analysis of a transmission wave from an FM-CW radar to obtain time domain frequency data, virtually calculates a receiving frequency characteristic based on this time domain frequency data, forms a beat signal using this receiving frequency characteristic, performs frequency analysis of the formed beat signal to obtain a target spectrum, and tests and evaluates the target detection performance of the FM-CW radar based on this target spectrum. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2005-241602 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the radar testing device of Patent Document 1 may not be able to properly simulate a radar (e.g., weather radar) that observes "soft targets" whose Doppler velocities fluctuate, such as clouds and precipitation. Here, a "soft target" refers to a target whose echo has a Doppler spread and a standard deviation. Also, "simulate" refers to reproducing the specifications of a target (especially a soft target) (e.g., reproducing in real time) so that the radar reflection factor and Doppler velocity of a radar (e.g., weather radar) can be correctly confirmed.

[0006] The present invention has been made in consideration of the above circumstances, and has as its main object to provide a radar test system that can properly simulate even a radar (e.g., a weather radar) that observes targets whose Doppler velocity varies, such as clouds and precipitation. [Means for solving the problem]

[0007] In order to achieve the above object, the radar test system of the present invention includes a receiving circuit that receives a signal from a test subject, a delay circuit that creates a fixed time delay in transmission without changing the waveform of the input signal, a fluctuation component injection circuit that generates a simulated target by injecting an average Doppler and a standard deviation of Doppler velocity as Doppler drift components into the input signal, a transmitting circuit that converts the input signal into a radio wave that can be transmitted, and a display control unit that controls the signals generated and processed by the delay circuit and the fluctuation component injection circuit. Effect of the Invention

[0008] The radar test system according to the present invention can appropriately simulate even a radar (for example, a weather radar) that observes targets whose Doppler velocities vary, such as clouds and precipitation. Note that the effects described herein are not necessarily limited to this range, and may be any of the effects described in this specification. [Brief description of the drawings]

[0009] [Figure 1] 1 is a block diagram showing an example of the configuration of a radar test system according to a first embodiment of the present invention. [Diagram 2] 1 is a block diagram showing an example of the configuration of a fluctuation component injection circuit in a radar test system according to a first embodiment of the present invention. [Diagram 3] FIG. 11 is a block diagram showing an example of the configuration of a radar test system according to a second embodiment of the present invention. [Figure 4] FIG. 11 is a block diagram showing an example of the configuration of a radar test system according to a third embodiment of the present invention. [Diagram 5] FIG. 11 is a block diagram showing an example of the configuration of a radar test system according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, preferred embodiments for carrying out the present invention will be described with reference to the drawings. Note that the embodiment described below shows an example of a typical embodiment of the present invention, and does not limit the scope of the present invention, and various combinations, modifications, and changes are possible within the scope of the gist of the present invention. In addition, in the description using the drawings, the same or equivalent elements are given the same reference numerals, and duplicated descriptions may be omitted.

[0011] <1. First embodiment> A radar test system according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG.

[0012] <1-1. Radar test system configuration> First, a configuration example of a radar test system 100 according to a first embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a block diagram showing a configuration example of the radar test system according to this embodiment.

[0013] The radar test system 100 is a radar test system that simulates "soft targets" whose Doppler velocity fluctuates, such as clouds and precipitation, by specifying the average Doppler μ and the standard deviation σ of the Doppler velocity as the Doppler drift components in the echo signal.

[0014] As shown in FIG. 1, the radar test system 100 includes a downconverter circuit 101, a delay circuit 102, a fluctuation component injection circuit 103, an upconverter circuit etc. 104, and a display control unit 105.

[0015] The downconverter circuit 101 is, for example, a circuit that receives radio waves from a weather radar under test and converts the high-frequency signal of the received radio waves into a low-frequency signal. Here, converting the high-frequency signal of the received radio waves into a low-frequency signal means lowering (reducing) the frequency of the received radio wave signal and converting it into a signal with a predetermined frequency. Note that a receiving circuit may be used instead of the downconverter circuit 101 (the same applies below).

[0016] The delay circuit 102 is connected to the downconverter circuit 101 and the fluctuation component injection circuit 103. The delay circuit 102 is a circuit that creates a certain time delay in the transmission of the radio wave signal input from the downconverter circuit 101 without changing the waveform of the signal.

[0017] The fluctuation component injection circuit 103 is connected to the delay circuit 102 and an up-converter circuit 104. The fluctuation component injection circuit 103 injects the average Doppler μ and the standard deviation σ of the Doppler velocity as the Doppler drift components into the echo signal of the radio wave input from the delay circuit 102 to simulate a "soft target."

[0018] The upconverter circuit 104 is a circuit that converts the low-frequency video signal of the simulated "soft target" into a high-frequency radio wave signal and transmits the converted radio wave to, for example, the weather radar under test. Here, converting the low-frequency video signal of the simulated "soft target" into a high-frequency radio wave signal means increasing (raising) the frequency of the video signal of the simulated "soft target" and converting it into a radio wave signal of a predetermined frequency. Note that a transmission circuit may be used instead of the upconverter circuit 104 (the same applies below).

[0019] The display control unit 105 is connected to the delay circuit 102 and the fluctuation component injection circuit 103, and controls the signals generated and processed in each circuit. The display control unit 105 can include a data generator .

[0020] The data generator 106 generates data for checking the echo of a "soft target" whose Doppler velocity fluctuates due to clouds, precipitation, etc., and the variance (deviation) of the Doppler velocity. Note that the display control unit 105 is not limited to having the data generator 106, and the fluctuation component injection circuit 103 may have the data generator 106.

[0021] Next, a configuration example of the fluctuation component injection circuit 103 in the radar test system 100 according to this embodiment will be described with reference to Fig. 2. Fig. 2 is a block diagram showing a configuration example of the fluctuation component injection circuit 103 in the radar test system 100.

[0022] As shown in FIG. 2, the fluctuation component injection circuit 103 includes, for example, an average Doppler frequency generating circuit 501, a fluctuation generator 502, a quadrature modulation section 503, and a fluctuation component combining circuit 504.

[0023] The average Doppler frequency generating circuit 501 is a circuit that generates I and Q signals at a frequency of an average Doppler μ as a Doppler drift component, and transmits the generated signals to the quadrature modulation unit 503 .

[0024] The fluctuation generator 502 is a generator that generates I and Q signals of noise with a Gaussian distribution in the Doppler direction and transmits the generated signals to the quadrature modulation unit 503. A simple way to generate Doppler fluctuations is to generate pseudo-random numbers using software or firmware, but it can also be created using hardware, using a thermal noise generator.

[0025] The orthogonal modulation unit 503 converts the analog I and Q signals input from the average Doppler frequency generating circuit 501 and the fluctuation generator 502 into radio waves or electrical signals, and outputs the modulated radio waves or electrical signals to the fluctuation component synthesis circuit 504.

[0026] The fluctuation component synthesis circuit 504 is a circuit that takes the sum of I and Q signals, which are quadrature modulated radio waves or electrical signals, and outputs the signal into which fluctuation has been injected to the up-converter or other circuit 104 .

[0027] <1-2. Radar test system operation> Next, an example of the operation of the radar test system 100 will be described with reference to FIGS.

[0028] First, the downconverter circuit 101 receives radio waves from the weather radar under test, converts the high-frequency signal of the received radio waves into a low-frequency signal, and outputs the low-frequency signal to the delay circuit 102.

[0029] Secondly, while the display control unit 105 controls the signal processing, the delay circuit 102 creates a certain time delay in the transmission of the input radio wave signal without changing its waveform, and outputs the signal to the fluctuation component injection circuit 103 .

[0030] Thirdly, while the display control unit 105 controls the signal generation, the fluctuation component injection circuit 103 injects the average Doppler μ and the standard deviation σ of the Doppler velocity as the Doppler drift components into the echo signal of the radio wave input from the delay circuit 102 to simulate a "soft target". At this time, the Doppler fluctuation component can be generated by the data generator 106 in the display control unit 105, or by the fluctuation generator 502 provided in the fluctuation component injection circuit 103. Thereafter, the fluctuation component injection circuit 103 outputs the echo signal of the simulated "soft target" to the upconverter circuit 104.

[0031] Fourth, the upconverter etc. circuit 104 converts the low frequency video signal of the simulated "soft target" into a high frequency radio wave signal and transmits the converted radio wave to the weather radar being tested.

[0032] According to the radar test system 100 of this embodiment, by injecting the average Doppler μ and the standard deviation σ of the Doppler velocity as the Doppler drift components into the echo signal of the radio wave to simulate a "soft target," it is possible to perform an appropriate simulation by observing the time difference of only one point of the soft target. This makes it possible to determine whether the radar performance is as designed.

[0033] The radar test system 100 can also simulate a "soft target" based on a test scenario generated by, for example, a real-time simulator. The radar test system 100 can also be applied to a radar test system that simulates a "hard target."

[0034] <2. Second embodiment> A radar test system according to a second embodiment of the present invention will be described with reference to Fig. 3. Fig. 3 is a block diagram showing an example of the configuration of a radar test system 200 according to this embodiment.

[0035] <2-1. Radar test system configuration> The radar test system 200 is a radar test system that simulates a simulated target (pseudo target) that has a "thickness" in the distance direction of the radar. The radar test system 200 differs from the radar test system 100 according to the first embodiment in that a branch circuit 201 is arranged between the downconverter circuit 101 and the delay circuit 102, and a synthesis circuit 202 is arranged between the fluctuation component injection circuit 103 and the upconverter circuit 104.

[0036] 3, the radar test system 200 includes a downconverter circuit 101, a branching circuit 201, a delay circuit 102, a fluctuation component injection circuit 103, a combining circuit 202, an upconverter circuit 104, and a display control unit 105. The display control unit 105 also includes a data generator 106.

[0037] The branching circuit 201 branches the radio wave signal input from the down-converter circuit 101 into a plurality of signals, and outputs the branched plurality of signals to the delay circuit 102 .

[0038] The synthesis circuit 202 synthesizes the echo signals of a plurality of “soft targets” input from the fluctuation component injection circuit 103 , and outputs the synthesized echo signal to the up-converter circuit 104 .

[0039] <2-2. Radar test system operation> Next, an example of the operation of the radar test system 200 will be described with reference to FIG.

[0040] First, the downconverter circuit 101 receives radio waves from the weather radar under test, converts the high-frequency signal of the received radio waves into a low-frequency signal, and outputs the low-frequency signal to the branch circuit 201 .

[0041] Secondly, the branching circuit 201 branches the radio wave signal input from the down-converter circuit 101 into a plurality of signals, and outputs the branched plurality of signals to the delay circuit 102 .

[0042] Thirdly, while the display control unit 105 controls the signal processing, the delay circuit 102 creates a certain time delay in the transmission of the multiple radio wave signals input from the branching circuit 201 without changing their waveforms, and outputs them to the fluctuation component injection circuit 103.

[0043] Thirdly, while the display control unit 105 controls signal generation, the fluctuation component injection circuit 103 injects the average Doppler μ and the standard deviation σ of the Doppler velocity as the Doppler drift components into the echo signals of the multiple radio waves input from the delay circuit 102 to simulate a "soft target". At this time, the Doppler fluctuation component can be generated by the data generator 106 in the display control unit 105, or by the fluctuation generator 502 provided in the fluctuation component injection circuit 103. Thereafter, the fluctuation component injection circuit 103 outputs the echo signals of the simulated "soft targets" to the synthesis circuit 202.

[0044] Fourth, the synthesis circuit 202 synthesizes the echo signals of the multiple “soft targets” input from the fluctuation component injection circuit 103 , and outputs the synthesized echo signal to the up-converter circuit 104 .

[0045] Fifth, an upconverter or similar circuit 104 converts the low frequency video signal of the composite "soft target" into a high frequency radio signal and transmits the converted radio signal to the weather radar under test.

[0046] According to the radar test system 200 of this embodiment, even if there is a “thickness” in the distance direction of the radar, it is possible to appropriately perform a simulation by simulating a “soft target” as in the first embodiment.

[0047] <3. Third embodiment> A radar test system according to a third embodiment of the present invention will be described with reference to Fig. 4. Fig. 4 is a block diagram showing an example of the configuration of a radar test system 300 according to this embodiment.

[0048] <3-1. Radar test system configuration> The radar test system 300 is a radar test system that simulates a simulated target (pseudo target) that has only "thickness" in the distance direction of the radar but has no Doppler fluctuation in the "thickness" direction. The radar test system 300 includes a first delay circuit 301 and a second delay circuit 302 in the delay circuit 102 of the radar test system 100 according to the first embodiment.

[0049] 4, the radar test system 300 includes a downconverter circuit 101, a branching circuit 201, a first delay circuit 301, a combining circuit 202, a second delay circuit 302, a fluctuation component injection circuit 103, an upconverter circuit 104, and a display control unit 105. The display control unit 105 also includes a data generator 106.

[0050] The branching circuit 201 branches the radio wave signal input from the down-converter circuit 101 into a plurality of signals, and outputs the branched plurality of signals to a first delay circuit 301 .

[0051] The first delay circuit 301 is a delay circuit for creating a certain time delay in transmission without changing the waveforms of the multiple radio wave signals input from the branch circuit 201, thereby producing "depth" in the distance direction. The amount of delay by the first delay circuit 301 is usually a value around the resolution of the radar, and the first delay circuit 301 is a circuit that realizes delays whose difference is about the distance resolution.

[0052] The combining circuit 202 combines the multiple radio wave signals input from the first delay circuit 301 , and outputs the combined radio wave signal to the second delay circuit 302 .

[0053] The second delay circuit 302 is a circuit that creates a certain time delay in the transmission of the radio wave signal input from the synthesis circuit 202 without changing the waveform, and provides a delay equivalent to the distance to the dummy target. The amount of delay provided by the second delay circuit 302 is usually larger than the amount of delay provided by the first delay circuit 301, and since the distance to the dummy target changes, the amount of delay and its amplitude are often variable in the second delay circuit 302. Therefore, the second delay circuit 302 is a circuit that achieves a delay that simulates the distance between the dummy target and the radar, and is usually much longer than the first delay circuit 301.

[0054] <3-2. Radar test system operation> Next, an example of the operation of the radar test system 300 will be described with reference to FIG.

[0055] First, the downconverter circuit 101 receives radio waves from the weather radar under test, converts the high-frequency signal of the received radio waves into a low-frequency signal, and outputs the low-frequency signal to the branch circuit 201 .

[0056] Secondly, the branching circuit 201 branches the radio wave signal input from the downconverter circuit 101 into a plurality of signals, and outputs the branched plurality of signals to the first delay circuit 301 .

[0057] Thirdly, first delay circuit 301 creates a certain time delay in the transmission of the multiple radio wave signals input from branching circuit 201 without changing their waveforms, and outputs the signals to combining circuit 202 .

[0058] Fourth, the combining circuit 202 combines the multiple radio wave signals input from the first delay circuit 301 and outputs the combined radio wave signal to the second delay circuit 302 .

[0059] Fifth, while the display control unit 105 controls the signal processing, the second delay circuit 302 creates a certain time delay in the transmission of the combined radio wave signal input from the combining circuit 202 without changing the waveform, and outputs it to the fluctuation component injection circuit 103.

[0060] Sixth, while the display control unit 105 controls signal generation, the fluctuation component injection circuit 103 injects the average Doppler μ and the standard deviation σ of the Doppler velocity as the Doppler drift components into the echo signal of the radio wave input from the second delay circuit 302 to simulate a "soft target". At this time, the Doppler fluctuation component can be generated by the data generator 106 in the display control unit 105, or by the fluctuation generator 502 provided in the fluctuation component injection circuit 103. Thereafter, the fluctuation component injection circuit 103 outputs the echo signal of the simulated "soft target" to the upconverter circuit 104.

[0061] Seventh, the upconverter etc. circuit 104 converts the low frequency video signal of the simulated "soft target" into a high frequency radio wave signal and transmits the converted radio wave to the weather radar being tested.

[0062] According to the radar test system 300 of this embodiment, even if there is only a “thickness” in the distance direction of the radar but no Doppler fluctuation in the “thickness” direction, it is possible to perform an appropriate simulation by simulating a “soft target” as in the first embodiment.

[0063] <4. Fourth embodiment> A radar test system according to a fourth embodiment of the present invention will be described with reference to Fig. 5. Fig. 5 is a block diagram showing an example of the configuration of a radar test system 400 according to this embodiment.

[0064] <4-1. Radar test system configuration> The radar test system 400 is a radar test system that generates a simulated target (pseudo target) having a "width" in the angle direction of the radar. The radar test system 400 includes the delay circuit 102 of the radar test system 100 according to the first embodiment, which includes a first delay circuit 301 and a second delay circuit 302, and also includes a plurality of up-converter circuits 104 (three in this embodiment, as an example).

[0065] 5, the radar test system 400 includes a downconverter circuit 101, a second delay circuit 302, a branching circuit 201, a first delay circuit 301, a fluctuation component injection circuit 103, a first upconverter circuit 401, a second upconverter circuit 402, a third upconverter circuit 403, and a display control unit 105. The display control unit 105 also includes a data generator 106.

[0066] The three upconverter circuits, ie, the first upconverter circuit 401 to the third upconverter circuit 403, each receive an echo signal from the fluctuation component injection circuit 103. The number of upconverter circuits included in the radar test system 400 is not limited to three, and may be two, four or more as long as there is more than one.

[0067] <4-2. Operation of the radar test system> Next, an example of the operation of the radar test system 400 will be described with reference to FIG.

[0068] First, the downconverter circuit 101 receives radio waves from the weather radar under test, converts the high-frequency signal of the received radio waves into a low-frequency signal, and outputs the low-frequency signal to the second delay circuit 302 .

[0069] Secondly, while the display control unit 105 controls the signal processing, the second delay circuit 302 creates a certain time delay in the transmission of the radio wave signal input from the downconverter circuit 101 without changing the waveform of the signal, and outputs it to the branch circuit 201.

[0070] Thirdly, the branch circuit 201 branches the radio wave signal input from the second delay circuit 302 into a plurality of signals, and outputs the branched plurality of signals to the first delay circuit 301 .

[0071] Fourth, first delay circuit 301 creates a certain time delay in the transmission of the multiple radio wave signals input from branch circuit 201 without changing their waveforms, and outputs the signals to fluctuation component injection circuit 103 .

[0072] Fifth, while the display control unit 105 controls signal generation, the fluctuation component injection circuit 103 injects the average Doppler μ and the standard deviation σ of the Doppler velocity as the Doppler drift components into the echo signals of the multiple radio waves input from the first delay circuit 301 to simulate multiple "soft targets." At this time, the Doppler fluctuation components can be generated by the data generator 106 in the display control unit 105, or by the fluctuation generator 502 provided in the fluctuation component injection circuit 103. After that, the fluctuation component injection circuit 103 outputs the echo signals of the simulated multiple "soft targets" to each of the upconverter circuits 401 to 403.

[0073] Sixth, the first upconverter circuit 401 to the third upconverter circuit 403 each input low-frequency video signals of multiple simulated "soft targets," convert them into high-frequency radio wave signals, and transmit the converted radio waves to the weather radar being tested.

[0074] According to the radar test system 400 of this embodiment, even when a simulated target (pseudo target) having a “width” in the angular direction of the radar is generated, a “soft target” is generated in a similar manner to the first embodiment, so that an appropriate simulation can be performed.

[0075] <5. Summary> In conventional "hard target" radars, a Doppler velocity v or a Doppler frequency fd is specified to simulate a target with that Doppler velocity. In contrast, the radar test systems 100 to 400 according to the above embodiments are radar test systems that simulate and generate "soft targets" such as clouds with a mean Doppler velocity μ and standard deviation σ.

[0076] As described above, the radar test system according to the present invention can also simulate targets that have a "thickness" in the distance direction or a "spread" in the angle direction for radar testing. In particular, by setting the "thickness" or "spread" to be equal to or less than the distance resolution or the angular resolution, it is possible to simulate a "soft target."

[0077] Specifically, by generating a data string of sufficient length (for example, 1 PRT or more if the target is a pulse Doppler radar, and preferably several PRTs or more if possible) with a term of mean velocity μ, mean velocity 0, and appropriate distribution (often Gaussian distribution) with standard deviation σ for the phase term of the "soft target," and using it repeatedly, it is possible to simulate a soft target with standard deviation σ.

[0078] The radar test system according to the present invention may include a scenario generating device. The scenario generating device generates a scenario (e.g., a weather scenario) based on past data (e.g., past weather data). The scenario generating device may, for example, perform machine learning on past weather data in advance, predict future weather using artificial intelligence, and generate a weather scenario according to the weather prediction data. Then, based on the scenario (e.g., the weather scenario), the radar test system according to the present invention may be implemented to test a radar (e.g., a weather radar). The scenario generating device may be provided as an external device to the radar test system according to the present invention. In this case, the scenario is transmitted to the radar test system according to the present invention as, for example, data, and after the transmission, the radar test system according to the present invention is implemented to test a radar (e.g., a weather radar).

[0079] The radar test system according to the present invention can be applied not only to a weather radar test system but also to a simulation system for ordinary "hard target" radars, such as weather clutter, sea clutter, or angel clutter. In addition, the system can be applied to generating stochastically fluctuating clutter other than ground clutter, which is generally a "hard target," and to evaluating the clutter suppression performance of the radar.

[0080] The present invention can have the following configuration. (1) a receiving circuit for receiving a signal from a test subject; A delay circuit that creates a certain time delay in transmission without changing the waveform of the input signal. a fluctuation component injection circuit for injecting an average Doppler and a standard deviation of a Doppler velocity as Doppler drift components into an input signal to generate a simulated target; A transmission circuit that converts the input signal into radio waves that can be transmitted; a display control unit that controls signals generated and processed by the delay circuit and the fluctuation component injection circuit. (2) A branching circuit that branches an input signal into a plurality of signals; The radar test system according to (1), further comprising a synthesis circuit that synthesizes a plurality of input signals. (3) The delay circuit includes a first delay circuit that applies a delay of a value around the resolution of the radar, and a second delay circuit that applies a delay corresponding to a distance to the simulated target, The radar test system according to (1), further comprising: a branching circuit that branches an input signal into a plurality of signals; and a combining circuit that combines the plurality of input signals. (4) the receiving circuit is a down-converter circuit that receives a signal from the test subject and converts the received high-frequency signal into a low-frequency signal; 2. The radar test system according to claim 1, wherein the transmission circuit is a circuit such as an up-converter that converts a low-frequency video signal into a high-frequency signal. (5) The delay circuit includes a first delay circuit that applies a delay of a value around the resolution of the radar, and a second delay circuit that applies a delay corresponding to a distance to the simulated target, A plurality of the up-converter circuits, The radar test system according to (4), further comprising a branching circuit that branches an input signal into a plurality of signals. (6) The radar test system according to any one of (1) to (5), further comprising a data generator for generating data for confirming target echoes whose Doppler velocities vary due to clouds, precipitation, etc., and the variance of the Doppler velocities. (7) The fluctuation component injection circuit is an average Doppler frequency generating circuit for generating a signal having an average Doppler frequency as a Doppler drift component; a fluctuation generator that generates a noise signal having a Gaussian distribution in the Doppler direction; a fluctuation component synthesis circuit that synthesizes the signals generated by the average Doppler frequency generation circuit and the fluctuation generator; 13. A radar test system according to claim 12, further comprising: [Explanation of symbols]

[0081] 100, 200, 300, 400 Radar Test Systems 101 Down converter circuit 102 Delay circuit 103 Fluctuation component injection circuit 104 Up-converter and other circuits 105 Display control unit 106 Data Generator 201 Branch Circuit 202 Synthesis circuit 301 First Delay Circuit 302 Second Delay Circuit 401 First up-converter etc. circuit 402 Second up-converter etc. circuit 403 3rd up-converter etc. circuit 501 Average Doppler Frequency Generator 502 Fluctuation Generator 503 Quadrature Modulation Section 504 Fluctuation Component Synthesis Circuit

Claims

1. a receiving circuit for receiving a signal from a test subject; A delay circuit that creates a certain time delay in transmission without changing the waveform of the input signal. a fluctuation component injection circuit for injecting an average Doppler and a standard deviation of a Doppler velocity as Doppler drift components into an input signal to generate a simulated target; A transmission circuit that converts the input signal into radio waves that can be transmitted; a display control unit that controls the signals generated and processed by the delay circuit and the fluctuation component injection circuit.

2. A branching circuit that branches an input signal into a plurality of signals; 2. The radar test system according to claim 1, further comprising: a synthesis circuit for synthesizing a plurality of input signals.

3. The delay circuit includes a first delay circuit that applies a delay of a value around the resolution of a radar, and a second delay circuit that applies a delay corresponding to a distance to the simulated target, 2. The radar test system according to claim 1, further comprising: a branching circuit that branches an input signal into a plurality of signals; and a combining circuit that combines the plurality of input signals.

4. the receiving circuit is a down-converter circuit that receives a signal from the test subject and converts the received high-frequency signal into a low-frequency signal; 2. The radar test system of claim 1, wherein the transmission circuit is an up-converter or similar circuit that converts a low frequency video signal to a higher frequency signal.

5. The delay circuit includes a first delay circuit that applies a delay of a value around the resolution of a radar, and a second delay circuit that applies a delay corresponding to a distance to the simulated target, A plurality of the up-converter circuits, 5. The radar test system according to claim 4, further comprising a branching circuit for branching an input signal into a plurality of signals.

6. 10. The radar test system of claim 1 further comprising a data generator for generating data for identifying target echoes with varying Doppler velocities such as clouds, precipitation, etc., and Doppler velocity variance.

7. The fluctuation component injection circuit is an average Doppler frequency generating circuit for generating a signal having an average Doppler frequency as a Doppler drift component; a fluctuation generator that generates a noise signal having a Gaussian distribution in the Doppler direction; 2. The radar test system according to claim 1, further comprising: a fluctuation component synthesis circuit for synthesizing the signals generated by said average Doppler frequency generation circuit and said fluctuation generator.

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