A radio frequency signal simulation control method

Abstract

This invention discloses a radio frequency (RF) signal simulation control method based on the equivalent control principle of RF signals in a semi-physical simulation system for radar countermeasures testing. This ensures that the interference-to-signal ratio (ISR) remains equivalent and consistent throughout the test. The method includes: determining a control reference signal M; under the driving force of the test scenario, the semi-physical simulation system calculates the target echo signal power and interference signal power for each simulation cycle; when the target echo signal power is less than the control reference signal M, both the interference signal and the target signal are controlled according to their actual calculated absolute values; when the target signal increases to the control reference signal M, the target power remains constant at the reference power, and the interference signal is normalized according to the reference signal while maintaining a constant real-time ISR. This invention, by changing the RF signal control from absolute to relative, can meet the large dynamic range simulation requirements of radar system signals while ensuring unchanged detection performance.

Description

Technical Field

[0001] This invention belongs to the field of radar countermeasures technology, and relates to a radar countermeasures simulation test method, and in particular to a radio frequency signal simulation control method. Background Technology

[0002] In radar countermeasures system tests, it is usually necessary to use a hardware-in-the-loop (HIL) system to simulate advanced radars with high power and long range. During the entire simulation test, the target echo and interference signal change range is large. When the signal control dynamic range of the existing HIL system does not meet the simulation requirements, it will directly lead to the unreliability of the simulated radar and make it difficult to achieve the purpose of verifying the performance of the radar countermeasures system. This brings great difficulty to the implementation of the test.

[0003] In the prior art, the radio frequency signal control equipment of the hardware-in-the-loop simulation system consists of a large number of digital devices and analog radio frequency devices. The radio frequency channel control unit in the analog radio frequency device is its control core, which consists of a radio frequency channel management computer and a radio frequency channel controller. The radio frequency channel controller analyzes and processes the combat data sent by the radio frequency channel management computer and the parameters of other sub-units, and generates control signals to control the sub-units, such as the generation of distance delay and Doppler parameters of DDM unit, the generation of interference patterns and data, the amplitude control of radio frequency channel, and the modulation of ABFU antenna pattern.

[0004] Currently, in the field of hardware-in-the-loop (HIL) simulation testing for radar countermeasures, HIL systems typically control radio frequency signals based on the absolute magnitude of the signal during testing. When the dynamic range of the system's signal control no longer meets the simulation requirements, the simulation system hardware needs to be replaced. However, due to the extreme complexity of the signal control equipment hardware, the cost of modification is extremely high, and the process is lengthy. Therefore, simulating more advanced simulation targets using the limited performance of HIL systems requires continuous iterative research to achieve this goal. Summary of the Invention

[0005] To address the problem that insufficient dynamic range of system signal control in existing hardware-in-the-loop simulation systems limits their radar simulation capabilities, this invention aims to provide a radio frequency signal simulation control method. This method transforms signal control from absolute magnitude control to relative magnitude control, which can meet the large dynamic range simulation requirements of radar system signals while ensuring unchanged detection performance. It achieves the experimental objective while greatly reducing experimental costs. The method is simple, time-saving, flexible, and timely.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0007] A radio frequency (RF) signal simulation control method, based on the RF signal equivalent control principle of a semi-physical simulation system for radar countermeasures testing, ensures that the interference-to-signal ratio remains equivalently consistent during the test; including:

[0008] Determine the control reference signal M: Under the driving force of the test situation, the hardware-in-the-loop simulation system calculates the target echo signal power and interference signal power for each simulation cycle. When the target echo signal power is less than the control reference signal M, both the interference signal and the target signal are controlled according to their actual calculated absolute values. When the target signal increases to the control reference signal M, the target power remains unchanged at the reference power, and the interference signal is normalized according to the reference signal while ensuring that the real-time interference-to-signal ratio remains unchanged, so as to ensure that the power of the interference signal is controlled within the upper limit of the actual dynamic range of the simulation system.

[0009] Furthermore, the selection requirements for the aforementioned control reference signal M include:

[0010] (a) Meets the requirements for the range of variation in the interference-to-signal ratio during coverage testing;

[0011] (b) Less than the saturation limit of the analog radar receiver;

[0012] (c) The noise floor requirement of the monitoring instrument during the test shall not be lower than that of the instrument.

[0013] A hardware-in-the-loop simulation system for radio frequency (RF) signal control, implementing the aforementioned RF signal simulation and control method, comprises a first down-conversion module, a second down-conversion module, a DDM delay and Doppler modulation module, a first amplitude control module, a second amplitude control module, a first ABFU antenna beamforming module, a second ABFU antenna beamforming module, an RF channel control module, a power combiner, and an up-conversion module, wherein...

[0014] The first down-conversion module is used to convert the radar transmitted signal into an intermediate frequency signal;

[0015] The second downconversion module is used to convert the interference signal into an intermediate frequency signal;

[0016] The DDM delay and Doppler modulation module is used to receive the intermediate frequency signal output by the first downconversion module, and to generate the target echo signal with delay, Doppler and amplitude characteristics.

[0017] The first amplitude control module is used to receive the target echo signal output by the DDM delay and Doppler modulation module, and to perform amplitude modulation on the target echo signal;

[0018] The second amplitude control module is used to receive the intermediate frequency signal output by the second downconverter module and to perform amplitude modulation on the intermediate frequency signal;

[0019] The first ABFU antenna beamforming module is used to receive the modulated signal output by the first amplitude control module and to modulate the radar antenna pattern.

[0020] The second ABFU antenna beamforming module is used to receive the modulated signal output by the second amplitude control module and to modulate the interference antenna pattern;

[0021] The radio frequency channel control module is used to receive combat information and parameters from the above modules, analyze and process them, and generate control signals to control the sub-units.

[0022] The power combiner is used to combine the signals output by the first ABFU antenna beamforming module and the second ABFU antenna beamforming module.

[0023] The upconversion module is used to receive the signal output by the power combiner and convert this signal into a radio frequency signal to output a target echo signal and an interference signal with time delay, Doppler and amplitude characteristics.

[0024] The control method for the radio frequency signal control device of the aforementioned hardware-in-the-loop simulation system includes the following steps:

[0025] Under the control of the RF channel control module, the first amplitude control module, and the second amplitude control module, the RF signal is controlled through pulse modulation and programmable attenuator modulation. The relative magnitude of the signal is controlled by modifying the control logic of the programmable attenuator amplitude control program in the first and second amplitude control modules. The control logic mainly follows the RF signal equivalent control principle. Its strategy is to set a control signal reference M. When the calculated target signal is less than the control reference signal, the simulation system controls according to the absolute magnitude of the signal. When the calculated signal is greater than the control reference signal, all signals are normalized according to the control reference signal to ensure that the interference-to-signal ratio is consistent with the calculated value during the experiment.

[0026] Due to the adoption of the technical solution described above, the present invention has the following advantages:

[0027] This radio frequency (RF) signal simulation control method establishes an equivalent control principle for RF signals in a semi-physical simulation test system, ensuring consistent interference-to-signal ratio during the test. This lays a scientific theoretical foundation for RF signal control methods based on unchanged detection performance. The RF control strategy changes the RF signal control from absolute to relative control, which can meet the large dynamic range simulation requirements of radar system signals while ensuring unchanged detection performance. It significantly improves the radar simulation capability of existing simulation systems at a relatively low cost, which is conducive to the development of advanced radar countermeasure technology tests. By transforming hardware technical problems into software model problems, the method is simple, time-saving, flexible, and timely, reducing the construction and testing costs of related simulation test systems and has good application value. Attached Figure Description

[0028] Figure 1 This is a structural block diagram of the radio frequency signal control device of the hardware-in-the-loop simulation system of the present invention;

[0029] Figure 2 This is a flowchart of an embodiment of the radio frequency signal simulation control method of the present invention;

[0030] Figure 3 This is a schematic diagram of the signal power change before the signal control was improved;

[0031] Figure 4 This is a schematic diagram of the signal power change after the signal control was improved;

[0032] Figure 5 This is a graph showing the trend of target signal change after actual measurement and improved signal control;

[0033] Figure 6 This is a graph showing the trend of interference signal changes after actual measurement and improvement of signal control. Detailed Implementation

[0034] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0035] The radio frequency signal simulation control method of the present invention is based on the equivalent control principle of radio frequency signals in a semi-physical simulation system for radar countermeasures tests. The equivalent radio frequency signal means that the signal detection performance of the simulated radar is consistent in both absolute control and relative control modes of the semi-physical simulation system throughout the entire radar countermeasures simulation test.

[0036] In radar detection, the Neyman-Pearson detector is commonly used. Detection theory dictates that radar target signal detection is a typical deterministic signal detection involving unknown parameters. The detection statistic approximates a probability density function with a mean-shifted Gaussian-Gaussian problem. In this case, the shift coefficient determines the detection performance. The shift coefficient is:

[0037]

[0038] Where T(x[n]) is the detection statistic; E(T(x[n]); H1) is the expected value of the statistic when the radar target signal is present; E(T(x[n]); H0) is the expected value of the statistic when the radar target signal is absent; var(T(x[n]); H0) is the variance of the statistic when the radar target signal is absent; d 2 The physical meaning of is the signal-to-noise ratio used for detection.

[0039] Based on the aforementioned offset coefficient d 2 In physical terms, for signal control, maintaining constant detection performance means controlling the relative magnitude of the signal, not its absolute magnitude. The principle of equivalent control for radio frequency signals is that signal control must ensure that the interference-to-signal ratio remains equivalent and consistent throughout the experiment.

[0040] A control reference signal M is determined. Under typical test conditions, the hardware-in-the-loop simulation system calculates the target echo signal power and interference signal power for each simulation cycle. When the target echo signal power is less than the control reference signal M, both the interference signal and the target signal are controlled according to their actual calculated absolute values. When the target signal increases to the control reference signal M, the target power remains constant at the reference power, and the interference signal is normalized according to the control reference signal while ensuring that the real-time interference-to-signal ratio remains constant, thereby ensuring that the power of the interference signal is controlled within the upper limit of the actual dynamic range of the simulation system.

[0041] Based on fully utilizing the actual dynamic range of the simulation system, the basic requirements for selecting the control reference signal M, as described above, include:

[0042] (a) Meets the requirements for the range of interference-to-signal ratio variation in the coverage test, with M being greater than the maximum interference-to-signal ratio during the test; (b) Meets the requirements for analog radar processing, with M being less than the upper limit of saturation of the analog radar receiver, ensuring that the AD chip of the analog radar RF receiver front-end and digital signal processor is not saturated; (c) Meets the requirements for easy monitoring, with stable system output signal, and M not less than the noise floor requirements of the monitoring instrument during the test.

[0043] like Figure 1 As shown, a hardware-in-the-loop (HIL) simulation system radio frequency (RF) signal control device includes a first down-conversion module, a second down-conversion module, a DDM delay and Doppler modulation module, a first amplitude control module, a second amplitude control module, a first ABFU antenna beamforming module, a second ABFU antenna beamforming module, an RF channel control module, a power combiner, and an up-conversion module.

[0044] The first down-conversion module is used to convert the radar transmitted signal into an intermediate frequency signal;

[0045] The second downconversion module is used to convert the interference signal into an intermediate frequency signal;

[0046] The DDM delay and Doppler modulation module is used to receive the intermediate frequency signal output by the first downconversion module, and to generate the target echo signal with delay, Doppler and amplitude characteristics.

[0047] The first amplitude control module is used to receive the target echo signal output by the DDM delay and Doppler modulation module, and to perform amplitude modulation on the target echo signal;

[0048] The second amplitude control module is used to receive the intermediate frequency signal output by the second downconverter module and to perform amplitude modulation on the intermediate frequency signal;

[0049] The first ABFU antenna beamforming module is used to receive the modulated signal output by the first amplitude control module and to modulate the radar antenna pattern.

[0050] The second ABFU antenna beamforming module is used to receive the modulated signal output by the second amplitude control module and to modulate the interference antenna pattern;

[0051] The radio frequency channel control module is used to receive combat information and parameters of the above modules (first downconversion module, second downconversion module, DDM delay and Doppler modulation module, first amplitude control module, second amplitude control module, first ABFU antenna beamforming module, and second ABFU antenna beamforming module), analyze and process them, and generate control signals for controlling the sub-units. The control signals include, but are not limited to, control of the receiving unit switch, intermediate frequency distribution unit pulse data, antenna pattern modulation, Doppler modulation, and electromagnetic wave propagation attenuation.

[0052] The power combiner is used to combine the signals output by the first ABFU antenna beamforming module and the second ABFU antenna beamforming module.

[0053] The upconversion module is used to receive the signal output by the power combiner and convert this signal into a radio frequency signal to output a target echo signal and an interference signal with time delay, Doppler and amplitude characteristics.

[0054] like Figure 2 As shown, the above-mentioned radio frequency signal simulation control method includes the following steps:

[0055] Step S1: Initialize parameters, set the current simulation cycle number i and the total number of cycles; based on the initial parameter settings, further determine whether to continue execution. If the current simulation cycle number i is less than the total number of cycles, proceed to step S2; otherwise, end.

[0056] Step S2: Based on the current simulation cycle number i, calculate the actual radar target echo signal power Sr(i) using simulation.

[0057] Step S3: Based on the current simulation cycle number i, calculate the actual interference signal power Sj(i) using simulation.

[0058] Step S4: Based on the radar target echo signal power of the current simulation period, further determine whether to adjust the signal amplitude. If the radar target echo signal power of the current simulation period is greater than the reference signal M, proceed to step S5; otherwise, proceed to step S1.

[0059] Step S5: Adjust the radar target echo signal power to M according to the current simulation period;

[0060] Step S6: Normalize the interference power according to the current simulation cycle, Sj(i) = Sj(i) - Sr(i) + M.

[0061] like Figure 3 As shown, the simulation example verifying the RF signal simulation control method of this invention is a schematic diagram of the signal power change before improvement. During the experiment, the target echo signal power is inversely proportional to the fourth power of the distance, increasing from -120dBm to approximately -30dBm, while the interference signal power is inversely proportional to the square of the distance, increasing from -80dBm to approximately -30dBm. The dynamic ranges of the two are 90dB and 50dB respectively. The 60dB dynamic range of the hardware-in-the-loop simulation test system cannot simultaneously guarantee the requirements of large dynamic range and control accuracy for both the echo signal and the interference signal.

[0062] like Figure 4 As shown, the simulation example of the RF signal simulation control method of this invention is a schematic diagram of the improved signal power change. First, the reference signal M for signal control is determined. The selection of M needs to consider three aspects: 1. The interference-to-signal ratio variation range in this example is approximately 45dB; 2. Assuming the maximum interference signal during the experiment is -20dBm, considering a pulse compression signal with a time-width-bandwidth product of 30dB, the maximum signal pulse compression must not exceed -20dBm, i.e., the target signal must not be greater than -50dBm; 3. Facilitating instrument monitoring. Considering that the noise floor of the spectrum analyzer at a bandwidth of 5MHz (signal bandwidth) is approximately -60dBm, to ensure that the signal power can be read by the instrument, the signal must not be less than -60dBm. Considering all these factors, the reference signal size is selected as -55dBm in this simulation example. When the target echo signal power is less than the reference signal, both the interference signal and the target signal are controlled according to the actual calculated absolute magnitude. When the target signal increases to the reference signal, the target power remains unchanged at -55dBm. The interference signal is normalized according to the reference signal while ensuring that the real-time interference-to-signal ratio remains unchanged. The interference-to-signal ratio varies by about 45dB, which is much smaller than the dynamic range when controlled according to the absolute magnitude of the signal.

[0063] like Figure 5 As shown in the example of the radio frequency signal simulation control method of the present invention, the intermediate frequency signal is obtained by performing AD quantization on the controlled radio frequency signal. The curve shows the trend of target signal change after the improved signal control. Due to the presence of interference, the target is detected in three distance segments. The general trend of target signal change is that it first increases and then remains unchanged. For precise control of the signal, the instrument is used to measure and verify the signal at typical values.

[0064] like Figure 6 As shown in the example of the radio frequency signal simulation control method of the present invention, the intermediate frequency signal is obtained by AD quantization of the controlled radio frequency signal. The curve shows the trend of interference signal change after the improved signal control. After the target signal increases to the reference signal, it is gradually reduced to keep the interference-to-signal ratio consistent with the actual solution. The interference-to-signal ratio of the system output signal remains unchanged before and after the adjustment, which does not affect the evaluation of the test results. For the precise control of the signal, the instrument is used to measure and verify the typical value.

[0065] An example of the radio frequency signal simulation control method of this invention works as follows: During the experiment, under the control of the radio frequency channel control module, the first amplitude control module, and the second amplitude control module, the radio frequency signal is controlled by pulse modulation and programmable attenuator modulation; the relative magnitude of the signal is controlled by modifying the control logic of the programmable attenuator amplitude control program in the first amplitude control module and the second amplitude control module; the control logic mainly follows the principle of equivalent control of radio frequency signals, and its strategy is to set a signal control reference M. When the calculated target signal is less than the reference signal, the simulation system controls according to the absolute magnitude of the signal; when the calculated signal is greater than the reference signal, all signals are normalized according to the reference signal to ensure that the interference-to-signal ratio is consistent with the calculated signal during the experiment.

[0066] The hardware-in-the-loop simulation system of this invention achieves signal control with unchanged detection performance according to the above control strategy, with short test preparation time, high system stability, and correct evaluation of radar countermeasure test results.

[0067] The above description is only a preferred embodiment of the present invention and not a limitation thereof. Any equivalent changes and modifications made in accordance with the scope of the present invention without departing from the spirit and scope of the present invention shall be within the scope of patent protection of the present invention.

Claims

1. A radio frequency signal simulation control method, characterized in that: Based on The equivalent control principle of radio frequency signals in the semi-physical simulation system for radar countermeasures testing ensures that the interference-to-signal ratio remains equivalently consistent throughout the test; including: Determine the control reference signal M: Under the driving force of the test situation, the hardware-in-the-loop simulation system calculates the target echo signal power and interference signal power for each simulation cycle; When the target echo signal power is less than the control reference signal M, both the interference signal and the target signal are controlled according to the actual calculated absolute magnitude. When the target signal increases to the control reference signal M, the target power remains unchanged at the reference power, and the interference signal is normalized according to the reference signal while ensuring that the real-time interference-to-signal ratio remains unchanged, so as to ensure that the power of the interference signal is controlled within the upper limit of the actual dynamic range of the simulation system.

2. The radio frequency signal simulation control method according to claim 1, characterized in that: The selection criteria for its control reference signal M include: (a) Meets the requirements for the range of variation in the interference-to-signal ratio during coverage testing; (b) Less than the upper limit of analog radar receiver saturation; (c) The noise level of the monitoring instrument during the test shall not be lower than the noise floor requirement.

3. A hardware-in-the-loop simulation system radio frequency signal control device for implementing the radio frequency signal simulation control method of claim 1 or 2, characterized in that: It includes a first down-conversion module, a second down-conversion module, a DDM delay and Doppler modulation module, a first amplitude control module, a second amplitude control module, a first ABFU antenna beamforming module, a second ABFU antenna beamforming module, an RF channel control module, a power combiner, and an up-conversion module, wherein... The first down-conversion module is used to convert the radar transmitted signal into an intermediate frequency signal; The second downconversion module is used to convert the interference signal into an intermediate frequency signal; The DDM delay and Doppler modulation module is used to receive the intermediate frequency signal output by the first downconversion module, and to generate the target echo signal with delay, Doppler and amplitude characteristics. The first amplitude control module is used to receive the target echo signal output by the DDM delay and Doppler modulation module, and to perform amplitude modulation on the target echo signal; The second amplitude control module is used to receive the intermediate frequency signal output by the second downconverter module and to perform amplitude modulation on the intermediate frequency signal; The first ABFU antenna beamforming module is used to receive the modulated signal output by the first amplitude control module and to modulate the radar antenna pattern. The second ABFU antenna beamforming module is used to receive the modulated signal output by the second amplitude control module and to modulate the interference antenna pattern; The radio frequency channel control module is used to receive combat information and parameters from the above modules, analyze and process them, and generate control signals to control the sub-units. The power combiner is used to combine the signals output by the first ABFU antenna beamforming module and the second ABFU antenna beamforming module. The upconversion module is used to receive the signal output by the power combiner and convert this signal into a radio frequency signal to output a target echo signal and an interference signal with time delay, Doppler and amplitude characteristics.

4. A control method for the radio frequency signal control device of the hardware-in-the-loop simulation system as described in claim 3, characterized in that: It includes the following steps: Under the control of the RF channel control module, the first amplitude control module, and the second amplitude control module, the RF signal is controlled through pulse modulation and programmable attenuator modulation. The relative magnitude of the signal is controlled by modifying the control logic of the programmable attenuator amplitude control program in the first and second amplitude control modules. The control logic mainly follows the RF signal equivalent control principle. Its strategy is to set a control signal reference M. When the calculated target signal is less than the control reference signal, the simulation system controls according to the absolute magnitude of the signal. When the calculated signal is greater than the control reference signal, all signals are normalized according to the control reference signal to ensure that the interference-to-signal ratio is consistent with the calculated value during the experiment.

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