Echo signal-to-noise ratio calibration method for infield space-fed radar semi-physical simulation system

Abstract

The invention discloses an echo signal-to-noise ratio calibration method for an infield space-fed radar semi-physical simulation system. The method comprises the following steps: calculating a theoretical signal-to-noise ratio in a simulation scene; quantizing the current echo data, and calculating the actual signal-to-noise ratio of the echo signal; judging whether the theoretical signal-to-noise ratio is greater than the current actual signal-to-noise ratio or not; if yes, adjusting the transmitting power of the radio frequency front end; if not, performing noise compensation on the digital back end; judging whether the difference between the actual signal-to-noise ratio and the theoretical signal-to-noise ratio of the echo signal after adjusting the transmitting power of the radio frequency front end or performing noise compensation on the digital rear end is smaller than a preset threshold value or not; if yes, calibration is completed. According to the method, the actual signal-to-noise ratio after original echo compensation is continuously close to the theoretical signal-to-noise ratio, and the problem that the actual signal-to-noise ratio is inconsistent with the theoretical signal-to-noise ratio in the working process simulated by the infield space-fed semi-physical simulation system is effectively solved.

Description

Technical Field

[0001] The invention belongs to the field of radar technology, and in particular relates to an echo signal-to-noise ratio calibration method for an indoor air-fed radar semi-physical simulation system. Background Art

[0002] Radar, as a kind of equipment with advantages such as all-day, all-weather and long detection distance, plays a vital role in modern information warfare. Radar not only realizes the function of discovering and locating targets by transmitting and receiving echo signals, but also can complete tasks such as target imaging, target identification and target scattering cross-sectional area measurement. Field experiments are an effective means for radar to verify system performance and evaluate combat effectiveness in actual combat environments. With the increasing complexity of radar systems and the accelerating iteration speed of radar technology, the cost of using field experiments to evaluate radar combat effectiveness is becoming more and more expensive and confidentiality is seriously threatened. Therefore, the simulation of indoor radar semi-physical simulation system is widely used in radar system performance verification and combat effectiveness evaluation due to its good flexibility, high fidelity and high repeatability.

[0003] The simulation system of the indoor radar semi-physical simulation system is generally composed of the RF front end, digital back end, cables / antennas, etc., and experiments are usually carried out indoors. The simulation of the indoor radar semi-physical simulation system can be divided into two types: injection type and air-fed type. Among them, the transceiver channel of the injection RF front end is connected with a cable, the signal is transmitted in the cable, and the characteristics of the target and the environment are described by a mathematical model; while the transceiver channel of the air-fed RF front end is connected to the transceiver antenna, and the transceiver antenna is connected to the detection loop. The simulation scene is constructed using a scaled model of the actual target to simulate the real process of signal propagation in the medium. Therefore, compared with the indoor injection semi-physical simulation system, the simulated working process of the indoor air-fed semi-physical simulation system is closer to the real working process of radar detection and has higher fidelity. However, the signal propagation path in the medium is uncontrollable and the actual transmission power of the RF front end deviates from the theoretical one, resulting in the actual signal-to-noise ratio of the original echo signal being inconsistent with the theoretical signal-to-noise ratio. This will affect the target detection, target recognition, target scattering cross-sectional area measurement, radar detection power, etc. of the digital back end. Therefore, the indoor air-fed semi-physical simulation system needs to measure and compensate the signal-to-noise ratio of the original echo signal, that is, signal-to-noise ratio calibration.

[0004] The existing signal-to-noise ratio calibration scheme includes: firstly, calculating the peak power of the linear frequency modulation signal after pulse compression and the average power of the noise pulse after compression, and calculating the signal-to-noise ratio of the signal after pulse compression; then calculating the actual signal-to-noise ratio of the original echo before pulse compression according to the pulse compression gain; finally, adjusting the corresponding transmission signal power according to the relationship between the actual signal-to-noise ratio and the theoretical signal-to-noise ratio.

[0005] However, the existing SNR calibration technology solution, which infers the actual SNR of the original echo by calculating the SNR of the signal after pulse compression, has low computational efficiency, is time-consuming, and is not suitable for complex experimental environments. Summary of the invention

[0006] In order to solve the above problems existing in the prior art, the present invention provides a method for calibrating the echo signal-to-noise ratio of an indoor air-fed radar semi-physical simulation system.

[0007] The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0008] A method for calibrating the echo signal-to-noise ratio of an indoor air-fed radar semi-physical simulation system, the system comprising a digital backend, a radio frequency frontend and a transceiver antenna; wherein the radio frequency frontend generates a radio frequency signal; the radio frequency signal is transmitted outwardly through the transceiver antenna; the transceiver antenna receives the echo signal, performs down-conversion, mixing, and analog / digital converter sampling on the received echo signal, and then forms echo data to be transmitted to the digital backend;

[0009] The calibration method comprises:

[0010] A. Calculate the theoretical signal-to-noise ratio in the simulation scenario;

[0011] B. Quantify the current echo data and calculate the actual signal-to-noise ratio of the echo signal;

[0012] C. Determine whether the theoretical signal-to-noise ratio is greater than the current actual signal-to-noise ratio; if the determination result is yes, execute step D; if the determination result is no, execute step E;

[0013] D. adjusting the transmission power of the RF front end, recalculating the actual signal-to-noise ratio of the echo signal, and then executing step F;

[0014] E. Perform noise compensation on the digital back end, recalculate the actual signal-to-noise ratio of the echo signal, and then execute step F;

[0015] F. Determine whether the difference between the actual signal-to-noise ratio currently calculated and the theoretical signal-to-noise ratio is less than a preset threshold; if so, complete the calibration; if not, receive new echo data and re-execute step B and subsequent steps.

[0016] Optionally, the calculation of the theoretical signal-to-noise ratio in the simulation scenario includes:

[0017]

[0018] Among them, SNR t The theoretical signal-to-noise ratio, P t is the radar transmission power, G tis the gain of the transmitting antenna in the transmitting and receiving antennas, G r is the gain of the receiving antenna in the transceiver antenna, λ is the wavelength of the RF signal, σ is the target scattering cross-sectional area, R is the distance between the target and the radar, k is the Boltzmann constant, T0 is the standard room temperature, B is the bandwidth of the RF signal, F is the system noise coefficient, and L is the system loss.

[0019] Optionally, quantifying the currently received echo data includes:

[0020] The integer echo data formed after the current analog / digital converter sampling is converted into floating-point echo data using a preset quantization coefficient.

[0021] Optionally, calculating the actual signal-to-noise ratio of the echo signal according to the quantized echo data includes:

[0022] Calculate the square of the modulus value of the quantized echo data as the original echo signal;

[0023] Detecting the starting position and the ending position of the target echo signal from the original echo signal;

[0024] According to the starting position and the ending position of the target echo signal, a noise sample and a mixed signal sample are extracted from the original echo signal; the mixed signal sample is a signal sample in which noise and the target echo signal are mixed;

[0025] Calculating noise power according to the noise samples, and calculating target echo signal power according to the mixed signal samples;

[0026] An actual signal-to-noise ratio of the echo signal is calculated according to the noise power and the target echo signal power.

[0027] Optionally, the detecting the starting position and the ending position of the target echo signal includes:

[0028] The starting position and the ending position of the target echo signal are detected by using a bidirectional unit average constant false alarm rate detection algorithm or a wavelet domain coherent edge detector.

[0029] Optionally, the noise sample is a vector with a length of L; the mixed signal sample is a vector with a length of M;

[0030] The calculating the noise power according to the noise sample comprises:

[0031]

[0032] Among them, n i is the i-th element of the noise sample, P Nr is the noise power;

[0033] The calculating the target echo signal power according to the mixed signal sample comprises:

[0034]

[0035] Among them, s i is the jth element of the mixed signal sample, P Nr is the noise power; P Sr is the target echo signal power.

[0036] Optionally, the method of detecting the starting position and the ending position of the target echo signal by using a bidirectional unit average constant false alarm rate detection algorithm includes:

[0037] The reference unit length of the bidirectional unit average constant false alarm rate detection algorithm is set, and the decision threshold of the bidirectional unit average constant false alarm rate detection algorithm is calculated by using the decision threshold calculation formula;

[0038] Inputting the decision threshold and the reference unit length into the bidirectional unit average constant false alarm rate detection algorithm to detect the starting position and the ending position of the target echo signal using the bidirectional unit average constant false alarm rate detection algorithm;

[0039] The decision threshold calculation formula is:

[0040]

[0041] Among them, P fa is the constant false alarm rate, M is the reference unit length set for the bidirectional unit average constant false alarm rate detection algorithm, x i is the i-th sample in the reference unit, D th is the decision threshold.

[0042] Optionally, the manner of performing noise compensation on the digital back end includes:

[0043] The power of the noise that needs to be compensated for in the digital backend is calculated using the following formula:

[0044]

[0045] Among them, P Sr is the target echo signal power, SNR t is the theoretical signal-to-noise ratio, P Nr is the noise power; P Nc The power of the noise that needs to be compensated by the digital backend

[0046] According to P Nc The digital back end is noise compensated.

[0047] Optionally, the manner of adjusting the transmit power of the radio frequency front end includes:

[0048] The transmit power that the RF front end needs to be adjusted to is calculated using the following formula:

[0049]

[0050] Wherein, P is the current transmit power of the RF front end, SNR r is the current actual signal-to-noise ratio; P′ is the transmit power that the RF front end needs to adjust to, SNR t is the theoretical signal-to-noise ratio;

[0051] A power control word corresponding to P′ is determined, and the power control word corresponding to P′ is sent to the radio frequency front end, so that the radio frequency front end generates a radio frequency signal of a corresponding size according to the power control word.

[0052] Compared with the prior art, the echo signal-to-noise ratio calibration method for the semi-physical simulation system of the indoor air-fed radar provided by the present invention has the following beneficial effects:

[0053] (1) The existing signal-to-noise ratio calibration scheme calculates the signal-to-noise ratio of the signal after pulse compression and then infers the original echo signal-to-noise ratio, which produces calculation errors. The present invention directly measures the signal-to-noise ratio of the original echo data to avoid such errors and improve the measurement accuracy.

[0054] (2) The existing signal-to-noise ratio calibration scheme calculates the signal-to-noise ratio of the signal after pulse compression and then infers the original echo signal-to-noise ratio. This scheme is time-consuming and inefficient. The technical scheme of measuring the signal-to-noise ratio of the original echo in the present invention reduces the processing time and improves the measurement efficiency compared with the existing technical scheme.

[0055] (3) The existing signal-to-noise ratio calibration scheme only considers the scheme for adjusting the signal transmission power, while the present invention uses two methods, digital back-end noise compensation and RF front-end transmission power adjustment, which can be applied to complex experimental scenarios.

[0056] The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a flow chart of a method for calibrating the echo signal-to-noise ratio of an indoor air-fed radar semi-physical simulation system provided by an embodiment of the present invention;

[0058] Figure 2 A simulation scene with completed settings is shown as an example;

[0059] Figure 3 It is a schematic diagram of the average constant false alarm rate detection algorithm of the bidirectional unit;

[0060] FIG4( a ) exemplarily shows an instantaneous power diagram of an echo signal input to a bidirectional unit average constant false alarm rate detection algorithm;

[0061] FIG4( b ) shows the detection result of the bidirectional unit average constant false alarm rate detection algorithm for the echo signal in FIG4( a );

[0062] Figure 5 A set of noise samples and mixed signal samples are shown as an example;

[0063] FIG6( a ) exemplarily shows a set of comparison results of the actual signal-to-noise ratio and the theoretical signal-to-noise ratio before and after noise compensation is performed on the digital back end;

[0064] FIG6( b ) exemplarily shows a set of comparison results between the actual signal-to-noise ratio and the theoretical signal-to-noise ratio before and after adjusting the transmit power of the RF front end. DETAILED DESCRIPTION

[0065] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0066] In view of the problem that the actual signal-to-noise ratio is inconsistent with the theoretical signal-to-noise ratio during the working process of the simulation of the indoor air-fed semi-physical simulation system, an embodiment of the present invention provides an echo signal-to-noise ratio calibration method for the indoor air-fed radar semi-physical simulation system. The method can make the actual signal-to-noise ratio after the original echo compensation continuously approach the theoretical signal-to-noise ratio, effectively solve the problem that the actual signal-to-noise ratio is inconsistent with the theoretical signal-to-noise ratio during the working process of the simulation of the indoor air-fed semi-physical simulation system, and improve the execution efficiency and flexibility of the indoor air-fed radar semi-physical simulation system when calibrating the echo signal-to-noise ratio.

[0067] The semi-physical simulation system of an indoor air-fed radar provided in an embodiment of the present invention includes a digital back end, a radio frequency front end and a transceiver antenna; wherein the radio frequency front end generates a radio frequency signal; the radio frequency signal is transmitted outwardly through the transceiver antenna; the transceiver antenna receives an echo signal, performs down-conversion, mixing, and analog / digital converter sampling on the received echo signal, and then forms echo data to be transmitted to the digital back end.

[0068] The echo signal-to-noise ratio calibration method provided by the embodiment of the present invention is as follows Figure 1 As shown, the following steps are included:

[0069] A. Calculate the theoretical signal-to-noise ratio in the simulation scenario.

[0070] In practice, there are many simulation scenarios. Figure 2 exemplarily shows a simulation scene that has been set up, which includes a radar and a flying target. It should be noted that the embodiment of the present invention does not limit the simulation scene.

[0071] For the simulation scenario, the theoretical signal-to-noise ratio in the simulation scenario is calculated, specifically including: setting the radar equipment parameters and target parameters according to the simulation scenario, and then calculating the theoretical signal-to-noise ratio. Among them, the radar equipment parameters may include the coordinates, antenna gain, and waveform parameters of the radar; the target parameters may include the target coordinates, speed, and target scattering cross-sectional area. After the simulation scenario is set, the theoretical signal-to-noise ratio in the simulation scenario can be calculated according to the basic radar equation. The calculation formula is as follows:

[0072]

[0073] Among them, SNR t is the theoretical signal-to-noise ratio, P t is the radar transmission power, G t is the gain of the transmitting antenna in the transceiver antenna, G r is the gain of the receiving antenna in the transceiver antenna, λ is the wavelength of the RF signal, σ is the target scattering cross-sectional area, R is the distance between the target and the radar, k is the Boltzmann constant, T0 is the standard room temperature, B is the bandwidth of the RF signal, F is the system noise coefficient, and L is the system loss.

[0074] When the radar equipment parameters in the simulation scenario are fixed, the above formula can be converted into:

[0075]

[0076] It can be seen that when the radar equipment parameters in the simulation scenario are fixed, the theoretical signal-to-noise ratio SNR t It only changes with the signal bandwidth B, and other parameters can be combined into a constant K0.

[0077] B. Quantify the current echo data and calculate the actual signal-to-noise ratio of the echo signal.

[0078] In the actual radar semi-physical simulation system, the digital backend sends a signal to generate a control word and a power control word to the RF front end. The RF front end generates a corresponding transmission signal pattern according to the received signal control word, and transmits a RF signal of corresponding power according to the received power control word. Then, the RF front end performs down-conversion, analog / digital converter sampling, and digital down-conversion on the RF signal containing echo data received by its receiving channel, and then transmits the original echo data to the digital back end. Since the main control chip of the RF front end is usually a field programmable gate array (FPGA), if the integer data after the analog / digital converter sampling is quantized into a floating point number in the FPGA, the computing resources of the FPGA will be wasted. Therefore, in the embodiment of the present invention, the echo data transmitted back by the RF front end is quantized at the digital back end.

[0079] Specifically, quantizing the current echo data includes: using a preset quantization coefficient to convert the integer echo data formed after the current analog / digital converter samples into floating-point echo data, which is expressed by the formula:

[0080] s o =A0d0,

[0081]

[0082] Among them, d0 is the integer echo data transmitted back by the RF front end, A0 is the quantization coefficient, n is the number of bits of the analog-to-digital converter, and s o It is the quantized floating-point echo data.

[0083] Then, the actual signal-to-noise ratio of the echo signal is calculated. Since the original echo signal is obtained by linearly superimposing the target echo signal and the noise, the actual signal-to-noise ratio of the echo signal calculated according to the quantized echo data may specifically include:

[0084] (1) Calculate the square of the modulus value of the quantized echo data as the original echo signal;

[0085] Specifically, the square of the modulus value of the quantized echo data is calculated as the original echo signal s0 is the quantized echo data, * represents conjugation, and s is the original echo signal.

[0086] (2) Detect the starting position and ending position of the target echo signal from the square modulus value s of the original echo signal.

[0087] Here, there are many specific implementation methods for detecting the starting position and the ending position of the target echo signal from the original echo signal. In order to make the layout of the specification clear, the specific implementation methods for detecting the starting position and the ending position of the target echo signal are described below with examples.

[0088] (3) According to the starting position and ending position of the target echo signal, noise samples and mixed signal samples are extracted from the original echo signal.

[0089] Here, the mixed signal sample is a signal sample in which noise and a target echo signal are mixed. Figure 5 A set of noise samples and mixed signal samples are shown as an example in FIG.

[0090] (4) calculating the noise power according to the noise samples, and calculating the target echo signal power according to the mixed signal samples;

[0091] Specifically, assuming that the noise sample is a vector with a length of L; the mixed signal sample is a vector with a length of M; then the noise power is calculated according to the noise sample, including:

[0092]

[0093] Among them, n i is the i-th element of the noise sample, P Nr is the noise power;

[0094] Calculate the target echo signal power based on the mixed signal samples, including:

[0095]

[0096] Among them, s i is the jth element of the mixed signal sample, P Nr is the noise power; P Sr is the target echo signal power.

[0097] (5) Calculate the actual signal-to-noise ratio of the echo signal based on the noise power and the target echo signal power.

[0098] Here, the calculation formula for calculating the actual signal-to-noise ratio of the echo signal based on the noise power and the target echo signal power is:

[0099] SNR r =P Sr / P Nr .

[0100] Among them, P Sr is the target echo signal power, P Nr is the noise power, SNR r is the actual signal-to-noise ratio.

[0101] C. Determine whether the theoretical signal-to-noise ratio is greater than the current actual signal-to-noise ratio; if the determination result is yes, execute step D; if the determination result is no, execute step E;

[0102] D. Adjust the transmit power of the RF front end, recalculate the actual signal-to-noise ratio of the echo signal, and then execute step F.

[0103] Specifically, there is the following relationship between the theoretical signal-to-noise ratio and the actual signal-to-noise ratio:

[0104]

[0105] in, Therefore, the following formula can be used to calculate the transmit power that the RF front end needs to be adjusted to:

[0106]

[0107] Wherein, P is the current transmit power of the RF front end, and P′ is the transmit power to which the RF front end needs to be adjusted.

[0108] Then, the transmit power of the RF front end is adjusted according to P′. The specific adjustment method is as follows:

[0109] (1) Use the following formula to calculate the transmit power that the RF front end needs to adjust to:

[0110]

[0111] Among them, P is the current transmit power of the RF front end, SNR r is the actual signal-to-noise ratio at present; P′ is the transmit power that the RF front end needs to adjust to, SNR t is the theoretical signal-to-noise ratio;

[0112] (2) Determine a power control word corresponding to P′, and send the power control word corresponding to P′ to the RF front end, so that the RF front end generates a RF signal of corresponding size according to the power control word.

[0113] After adjusting the transmit power of the RF front end, the transmit power of the RF front end changes, receives a new echo signal, re-forms echo data to the digital back end, recalculates the actual signal-to-noise ratio in the same manner as in step B, and then continues to step F.

[0114] E. Perform noise compensation on the digital back end, recalculate the actual signal-to-noise ratio of the echo signal, and then execute step F.

[0115] Specifically, the original echo signal is obtained by linearly superimposing the target echo signal and the noise, so the theoretical signal-to-noise ratio can be expressed as:

[0116]

[0117] Among them, P Nt is the theoretical signal-to-noise ratio SNR r The corresponding noise power, P Nr is the actual noise power, P Nc This is the power of the noise that needs to be compensated by the digital backend.

[0118] Accordingly, the power of the noise that needs to be compensated by the digital backend can be calculated using the following formula:

[0119]

[0120] Then, according to P Nc Noise compensation is performed on the digital backend. After noise compensation is performed on the digital backend, the echo signal at this time is expressed as:

[0121]

[0122] Among them, s0 is the original echo signal, n0 is the Gaussian noise generated by the digital backend, and its power is about 1W.

[0123] Then, the actual signal-to-noise ratio is recalculated in the same manner as in step B, and step F is continued.

[0124] F. Determine whether the difference between the actual signal-to-noise ratio and the theoretical signal-to-noise ratio currently calculated is less than a preset threshold; if so, complete the calibration; if not, receive new echo data and re-execute step B and subsequent steps.

[0125] The threshold may be set to 0.5 dB, but is not limited thereto.

[0126] FIG6(a) shows a set of comparison results of the actual signal-to-noise ratio and the theoretical signal-to-noise ratio before and after the noise compensation of the digital backend, where the solid line is the theoretical signal-to-noise ratio, the dotted line is the actual signal-to-noise ratio before the noise compensation of the digital backend, and "*" is the actual signal-to-noise ratio after the noise compensation of the digital backend. It can be seen from FIG6(a) that the actual signal-to-noise ratio after compensation is basically consistent with the theoretical signal-to-noise ratio, which means that by performing noise compensation on the echo signal whose actual signal-to-noise ratio is greater than the theoretical signal-to-noise ratio through the digital backend noise compensation scheme, the absolute value of the difference between the actual signal-to-noise ratio and the theoretical signal-to-noise ratio can be made less than the signal-to-noise ratio compensation accuracy.

[0127] FIG6(b) shows a set of comparison results of the actual signal-to-noise ratio and the theoretical signal-to-noise ratio before and after adjusting the transmit power of the RF front end, where the solid line is the theoretical signal-to-noise ratio, the dotted line is the actual signal-to-noise ratio before adjusting the transmit power of the RF front end, and "*" is the actual signal-to-noise ratio before and after adjusting the transmit power of the RF front end. As can be seen from FIG6(b), the actual signal-to-noise ratio after compensation is basically consistent with the theoretical signal-to-noise ratio, which means that by performing transmit power compensation on the echo signal whose actual signal-to-noise ratio is less than the theoretical signal-to-noise ratio through the RF front end transmit power adjustment scheme, the absolute value of the difference between the actual signal-to-noise ratio and the theoretical signal-to-noise ratio can be made less than the signal-to-noise ratio compensation accuracy.

[0128] In summary, compared with the prior art, the method for calibrating the echo signal-to-noise ratio of the semi-physical simulation system of the indoor air-fed radar provided in the embodiment of the present invention has the following beneficial effects:

[0129] (1) The existing signal-to-noise ratio calibration scheme calculates the signal-to-noise ratio of the signal after pulse compression and then infers the original echo signal-to-noise ratio, which produces calculation errors. The present invention directly measures the signal-to-noise ratio of the original echo data to avoid such errors and improve the measurement accuracy.

[0130] (2) The existing signal-to-noise ratio calibration scheme calculates the signal-to-noise ratio of the signal after pulse compression and then infers the original echo signal-to-noise ratio. This scheme is time-consuming and inefficient. The technical scheme of measuring the signal-to-noise ratio of the original echo in the present invention reduces the processing time and improves the measurement efficiency compared with the existing technical scheme.

[0131] (3) The existing signal-to-noise ratio calibration scheme only considers the scheme for adjusting the signal transmission power, which is not flexible and is not suitable for complex experimental environments. The present invention uses two methods, digital back-end noise compensation and RF front-end transmission power adjustment, which can be applied to complex experimental scenarios.

[0132] The following is an example of a specific implementation method for detecting the start position and the end position of the target echo signal from the original echo signal.

[0133] Exemplarily, in one implementation, a bidirectional unit average constant false alarm rate detection algorithm can be used to detect the starting position and the ending position of the target echo signal from the original echo signal. Specifically, the following steps are included:

[0134] (1) setting a reference unit length of a bidirectional unit average constant false alarm rate detection algorithm, and calculating a decision threshold of the bidirectional unit average constant false alarm rate detection algorithm using a decision threshold calculation formula;

[0135] Before setting the reference unit length of the bidirectional unit average constant false alarm rate detection algorithm, a protection unit of a suitable length may be selected to prevent the reference unit from being affected by the detection unit.

[0136] The decision threshold calculation formula is:

[0137]

[0138] Where P fa is the constant false alarm rate, M is the reference unit length set for the bidirectional unit average constant false alarm rate detection algorithm, x i is the i-th sample in the reference unit, D th is the decision threshold.

[0139] (2) The decision threshold and the reference unit length are input into the bidirectional unit average constant false alarm rate detection algorithm, so as to use the bidirectional unit average constant false alarm rate detection algorithm to detect the starting position and the ending position of the target echo signal from the echo signal.

[0140] Specifically, the original echo signal is subjected to a forward unit average constant false alarm rate detection to obtain the starting position of the target echo signal; the original echo signal is subjected to a reverse unit average constant false alarm rate detection to obtain the ending position of the target echo signal.

[0141] Figure 3FIG4( a ) shows a schematic diagram of a two-way unit average constant false alarm rate detection algorithm, and FIG4( a ) shows an exemplary power spectrum of an echo signal input to the two-way unit average constant false alarm rate detection algorithm, wherein the starting position of the target echo signal is marked as 266.867 us and the ending position is marked as 394.067 us. FIG4( b ) shows the detection result of the two-way unit average constant false alarm rate detection algorithm for the echo signal in FIG4( a ), and it can be seen that the starting position 266.667 us and the ending position 394.067 us of the detected target echo signal are basically consistent with those marked in FIG4( a ).

[0142] In another implementation, a wavelet domain coherent edge detector detection algorithm may be used to detect the starting position and the ending position of the target echo signal from the original echo signal. For the specific detection method, please refer to the related prior art and will not be described in detail in the embodiment of the present invention.

[0143] It should be noted that the terms "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure.

[0144] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0145] Although the present application is described herein in conjunction with various embodiments, in the process of implementing the claimed application, those skilled in the art can understand and implement other changes to the disclosed embodiments by viewing the drawings and the disclosed content. In the description of the present invention, the term "comprising" does not exclude other components or steps, "one" or "an" does not exclude multiple situations, and the meaning of "multiple" is two or more, unless otherwise clearly and specifically limited. In addition, certain measures are recorded in different embodiments, but this does not mean that these measures cannot be combined to produce good results.

[0146] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, devices (equipment), or computer program products. Therefore, the present application may adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware, which are collectively referred to as "modules" or "systems" herein. Moreover, the present application may adopt the form of computer program products implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program codes. The computer program is stored / distributed in a suitable medium, provided together with other hardware or as a part of hardware, or may adopt other distribution forms, such as by Internet or other wired or wireless telecommunication systems.

[0147] The present application is described with reference to the flowcharts and / or block diagrams of the methods, apparatuses (devices) and computer program products of the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0148] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0149] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0150] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A method for calibrating the echo signal-to-noise ratio of an indoor air-fed radar semi-physical simulation system, characterized in that: The system includes a digital backend, a radio frequency frontend and a transceiver antenna; wherein the radio frequency frontend generates a radio frequency signal; the radio frequency signal is transmitted outwardly through the transceiver antenna; the transceiver antenna receives an echo signal, performs down-conversion, mixing, and analog / digital converter sampling on the received echo signal, and then forms echo data to be transmitted to the digital backend; The calibration method comprises: A. Calculate the theoretical signal-to-noise ratio in the simulation scenario; B. Quantify the current echo data and calculate the actual signal-to-noise ratio of the echo signal; C. Determine whether the theoretical signal-to-noise ratio is greater than the current actual signal-to-noise ratio; if the determination result is yes, execute step D; if the determination result is no, execute step E; D. adjusting the transmission power of the RF front end, recalculating the actual signal-to-noise ratio of the echo signal, and then executing step F; E. Perform noise compensation on the digital back end, recalculate the actual signal-to-noise ratio of the echo signal, and then execute step F; F. Determine whether the difference between the actual signal-to-noise ratio currently calculated and the theoretical signal-to-noise ratio is less than a preset threshold; if so, complete the calibration; if not, receive new echo data and re-execute step B and subsequent steps.

2. The calibration method according to claim 1, characterized in that: The theoretical signal-to-noise ratio in the calculation simulation scenario includes: Among them, SNR t The theoretical signal-to-noise ratio, P t is the radar transmission power, G t is the gain of the transmitting antenna in the transmitting and receiving antennas, G r is the gain of the receiving antenna in the transceiver antenna, λ is the wavelength of the RF signal, σ is the target scattering cross-sectional area, R is the distance between the target and the radar, k is the Boltzmann constant, T0 is the standard room temperature, B is the bandwidth of the RF signal, F is the system noise coefficient, and L is the system loss.

3. The calibration method according to claim 1, characterized in that: The quantifying of the currently received echo data includes: The integer echo data formed after the current analog / digital converter sampling is converted into floating-point echo data using the preset quantization coefficient.

4. The calibration method according to claim 1, characterized in that: The calculating the actual signal-to-noise ratio of the echo signal according to the quantized echo data comprises: Calculate the square of the modulus value of the quantized echo data as the original echo signal; Detecting the starting position and the ending position of the target echo signal from the original echo signal; According to the starting position and the ending position of the target echo signal, a noise sample and a mixed signal sample are extracted from the original echo signal; the mixed signal sample is a signal sample in which noise and the target echo signal are mixed; Calculating noise power according to the noise samples, and calculating target echo signal power according to the mixed signal samples; An actual signal-to-noise ratio of the echo signal is calculated according to the noise power and the target echo signal power.

5. The calibration method according to claim 4, characterized in that: The detection of the starting position and the ending position of the target echo signal includes: The starting position and the ending position of the target echo signal are detected by using a bidirectional unit average constant false alarm rate detection algorithm or a wavelet domain coherent edge detector.

6. The calibration method according to claim 4, characterized in that: The noise sample is a vector with a length of L; the mixed signal sample is a vector with a length of M; The calculating the noise power according to the noise sample comprises: Among them, n i is the i-th element of the noise sample, P Nr is the noise power; The calculating the target echo signal power according to the mixed signal sample comprises: Among them, s i is the jth element of the mixed signal sample, P Nr is the noise power; P Sr is the target echo signal power.

7. The calibration method according to claim 5, characterized in that: The method of detecting the starting position and the ending position of the target echo signal by using the bidirectional unit average constant false alarm rate detection algorithm includes: The reference unit length of the bidirectional unit average constant false alarm rate detection algorithm is set, and the decision threshold of the bidirectional unit average constant false alarm rate detection algorithm is calculated by using the decision threshold calculation formula; Inputting the decision threshold and the reference unit length into the bidirectional unit average constant false alarm rate detection algorithm to detect the starting position and the ending position of the target echo signal using the bidirectional unit average constant false alarm rate detection algorithm; The decision threshold calculation formula is: Among them, P fa is the constant false alarm rate, M is the reference unit length set for the bidirectional unit average constant false alarm rate detection algorithm, x i is the i-th sample in the reference unit, D th is the decision threshold.

8. The calibration method according to claim 1, characterized in that: The method of performing noise compensation on the digital back end includes: The power of the noise that needs to be compensated for in the digital backend is calculated using the following formula: Among them, P Sr is the target echo signal power, SNR t is the theoretical signal-to-noise ratio, P Nr is the noise power; P Nc The power of the noise that needs to be compensated by the digital backend According to P Nc The digital back end is noise compensated.

9. The calibration method according to claim 1, characterized in that: The method of adjusting the transmission power of the radio frequency front end includes: The transmit power that the RF front end needs to be adjusted to is calculated using the following formula: Wherein, P is the current transmit power of the RF front end, SNR r is the current actual signal-to-noise ratio; P′ is the transmit power that the RF front end needs to adjust to, SNR t is the theoretical signal-to-noise ratio; A power control word corresponding to P′ is determined, and the power control word corresponding to P′ is sent to the radio frequency front end, so that the radio frequency front end generates a radio frequency signal of a corresponding size according to the power control word.

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