Radio correction command error detection method for direct radio frequency sampling iq signals

Abstract

The application provides a radio correction instruction error code detection method of a direct radio frequency sampling IQ signal, and the radio correction instruction error code detection technology of the direct radio frequency sampling IQ signal directly collects, digitizes, frequency down-converts the intermittent radiation radio frequency signal of a radar into I and Q two-way signals, and obtains modulation parameter information through only one demodulation, obtains the radio correction instruction through a matching filter, and compares the radio correction instruction with a standard instruction code recovery signal to realize error code detection and error code positioning. The technology has clear principles, simple implementation approaches, accurate standards, and can be applied to error code detection of different types of radio correction instructions.

Description

Technical Field

[0001] This invention belongs to the field of guidance technology in radio electronics, and specifically relates to a method for detecting radio correction command errors in directly sampled radio frequency (RF) IQ signals. Background Technology

[0002] Currently, the calibration of bit error rate, modulation index, and other coding characteristics and dynamic characteristics of radar guidance signal radio correction commands in missile integrated testing equipment adopts the standard seeker function calibration method. The standard seeker receives the radar guidance signal, and the onboard computer / decoder encodes and parses the guidance command based on the guidance information to obtain the guidance command requirements. The performance of the radar guidance signal radio correction command is judged by the quality of the standard seeker's reception. The disadvantages of this method are: because the standard seeker is pre-programmed with address codes, it only receives guidance information in the radar guidance signal radio correction command that matches its address code, and does not respond to radio correction commands sent to other seekers. Therefore, it cannot obtain complete radar guidance signal radio correction command encoding information, thus failing to determine the correctness of the radio correction command throughout the entire cycle. Furthermore, when decoding the radio correction command, the standard seeker can only determine whether it can be decoded correctly, but cannot determine the occurrence of errors or locate their positions. Therefore, the method of calibrating radar guidance signal radio correction commands using the standard seeker can only qualitatively determine the technical characteristics of the radar guidance signal radio correction command, and cannot quantitatively calibrate related values. Summary of the Invention

[0003] The purpose of this invention is to provide a method for detecting bit error rate of radio correction command signals by directly sampling IQ signals, thereby solving the technical problems of bit error rate detection and error location of radio correction command signals.

[0004] The technical solution adopted in this invention is as follows:

[0005] A method for detecting radio correction command errors in directly sampled IQ signals includes the following steps:

[0006] Step 1: Directly acquire I and Q signal data from the radio frequency signal, perform digital processing, and store the data in the IQ data storage module;

[0007] Step 2: Read the I and Q signal data, and obtain the mixed time-domain signal through two-stage demodulation;

[0008] Step 3: Encode and detect the mixed time-domain signal to obtain radio correction instruction symbols;

[0009] Step 4: Perform a matching operation between the radio correction command symbols and the standard radio correction command error codes to achieve error detection and error location.

[0010] Furthermore, step 1 specifically includes the following steps:

[0011] Step 11: Feed the radio frequency signal from the antenna into the limiter;

[0012] Step 12: The radio frequency signal after the limiter is passed through a low noise amplifier and narrowband filtering is performed to remove in-band and in-band interference signals.

[0013] Step 13: After adjusting the gain of the variable gain amplifier, the magnitude of the RF signal is made to fall within the dynamic processing range of the ADC.

[0014] Step 14: Perform anti-aliasing filtering using a bandpass filter;

[0015] Step 15: The sample is sent to the ADC for bandpass sampling and digitization.

[0016] Step 16: After digital processing, the signal is converted into baseband I and Q signals by digital down-conversion and filtering, and the I and Q data are stored in the IQ data storage module. The I and Q signals are a pair of phase-quadrature modulation signals.

[0017] Furthermore, step 2 specifically includes the following steps:

[0018] Step 21: Read the IQ data from the IQ data storage module, and obtain the baseband envelope signal by performing a sum of squares operation on the I and Q signals;

[0019] Step 22: The baseband envelope signal is low-pass filtered to obtain the load wave signal;

[0020] Step 23: The load wave signal is demodulated in one stage to obtain a hybrid time-domain modulated signal;

[0021] Step 24: Perform two-stage demodulation on the hybrid time-domain modulated signal to obtain the hybrid time-domain signal.

[0022] Furthermore, in step 23, the first-level demodulation is phase demodulation, which employs an orthogonal demodulation algorithm. Software radio technology is used to process the orthogonal dual channels separately to obtain a hybrid time-domain modulated signal.

[0023] Furthermore, in step 24, the secondary demodulation is software coherent demodulation, and a hybrid time-domain signal is obtained through software coherent demodulation.

[0024] Furthermore, step 3 specifically includes the following steps:

[0025] Step 31: Set narrowband filter banks with different thresholds according to the modulation frequency of the mixed time-domain signal;

[0026] Step 32: Perform matched filtering on the mixed time-domain signal to separate each modulation signal;

[0027] Step 33: Obtain the modulation frequency carried in the mixed time domain signal by filtering, and obtain the radio correction instruction code through frequency mapping coding detection.

[0028] Furthermore, in step 4, the radio correction command symbols and standard radio correction command errors are matched using an error matching algorithm.

[0029] Furthermore, step 4 specifically includes the following steps:

[0030] Step 41: Obtain the radio correction instruction code elements obtained from the encoding detection by sorting and combining them to obtain the radio correction instruction;

[0031] Step 42: Perform error matching calculation between the radio correction command and the standard radio correction command, and statistically analyze the verification results. The ratio of the number of errors to the total number of detections is the bit error rate. Since all radio correction commands are collected and stored, the location of the error in the entire cycle can be determined when calculating the bit error rate, which can be judged as an occasional occurrence or a device malfunction.

[0032] Compared with the prior art, the advantages of the present invention are that the principle is clear, the implementation is simple, the calibration is accurate, and it can be applied to the detection of error codes in different types of radio correction commands. Attached Figure Description

[0033] Figure 1 This is a block diagram illustrating the principle of radio correction command bit error detection for direct radio frequency sampling IQ signals according to the present invention.

[0034] Figure 2 This is a block diagram illustrating the direct radio frequency sampling principle of the present invention;

[0035] Figure 3 This is a block diagram illustrating the two-stage demodulation principle of IQ data in this invention.

[0036] Figure 4 This is a block diagram illustrating the principle of the orthogonal demodulation algorithm of this invention.

[0037] Figure 5 This is a block diagram illustrating the symbol detection principle of the radio correction command of the present invention;

[0038] Figure 6 This is a block diagram illustrating the principle of symbol error detection for the radio correction command of the present invention. Detailed Implementation

[0039] The radio correction command error detection technology for direct RF sampling IQ signals provided by this invention directly acquires radar intermittent radiated RF signals, digitizes them into I and Q signals via down-conversion, and obtains modulation parameter information through only one demodulation stage. The radio correction command is then obtained after passing through a matched filter and compared with the standard command encoded and recovered signal to achieve error detection and error location. The specific embodiments of this invention are further described in detail below with reference to the accompanying drawings. It should be noted that the drawings are all in a very simplified form and use non-precise ratios, and are only used to facilitate and clarify the purpose of illustrating the embodiments of this invention.

[0040] Radar radio frequency signals are transmitted in an intermittent illumination manner. During continuous illumination, radio correction commands are loaded onto the carrier frequency and transmitted continuously. That is, a combination of subcarrier signals is modulated onto the carrier signal. The radio correction commands, represented by a specified subcarrier signal combination, are encoded to form the radar radio frequency signal command. The mathematical expression for the intermittently radiated radar radio frequency signal is shown in formula (1):

[0041]

[0042] In the formula,

[0043] K(t) — the switching function of intermittent radiation;

[0044] f0 — carrier signal frequency;

[0045] U0 — Carrier signal amplitude;

[0046] t — time;

[0047] β0 — Subcarrier modulation index;

[0048] A(t) – the amplitude envelope of the subcarrier;

[0049] f i ———The frequency of the subcarrier;

[0050] a i ———The presence or absence of the subcarrier frequency signal, with a value of 0 or 1.

[0051] The amplitude envelope of the subcarrier is a functional relationship, namely:

[0052]

[0053] Here, τ d The fixed period (in μs) is the amplitude envelope of the subcarrier.

[0054] In terms of mathematical expression, the phase component is a composite modulated signal of a set of subcarrier frequency signals, meaning the time domain waveform contains multiple frequency signals. Its envelope is an amplitude-modulated signal envelope, mathematically expressed as: Where f d The fixed frequency is the subcarrier amplitude envelope. Based on the above principles and mathematical model analysis, the demodulation path is determined. The intermittently radiated radio frequency signal of the radar is a composite modulated signal, in which the radio correction command information accounts for less than 0.01%. When detecting its bit error rate, a large amount of raw data needs to be accumulated for demodulation processing. The actual IQ memory capacity used is 1TB.

[0055] like Figure 1 As shown, the radio correction command error detection method for directly sampling I and Q signals of the present invention first directly collects and stores the I and Q signal data of the radio frequency signal, obtains a mixed time-domain signal through two-stage demodulation, obtains the radio correction command through encoding detection, and achieves error detection by comparing it with the standard command encoded and recovered signal. The processing procedure is described in detail below.

[0056] Step 1, as follows Figure 2 As shown, direct RF sampling directly digitizes the RF signal. It utilizes the principles of software-defined radio to bring the analog-to-digital (A / D) and digital-to-analog (D / A) converters as close to the antenna as possible, directly digitizing the RF signal. The carrier wave is an X-band intermittently illuminating radar RF signal fed into the antenna. First, it passes through a limiter to prevent large signal reflections or feeds that could damage the receiver. The signal after the limiter passes through a low-noise amplifier (LNA) and undergoes narrowband filtering to remove in-band and in-band interference signals. After passing through a variable gain amplifier with gain settings, the signal magnitude falls within the dynamic processing range of the ADC. It then passes through a bandpass filter for anti-aliasing filtering and is fed into a high-speed, high-precision ADC for bandpass sampling. The digitized signal is then digitally down-converted and filtered to convert it into baseband I-channel and Q-channel signals, and the IQ data is stored. The I-channel and Q-channel signals are a pair of orthogonally phase modulated signals.

[0057] Step 2, as follows Figure 3 As shown, the IQ data in the IQ data storage module is read, and the I and Q signals are squared to obtain the baseband envelope signal. After low-pass filtering, a first-stage demodulation is performed. The first-stage demodulation is mainly phase demodulation, which adopts an orthogonal demodulation algorithm. Using software radio technology, the orthogonal dual channels are processed separately to obtain a hybrid time-domain modulated signal. The principle block diagram of the orthogonal demodulation algorithm is shown below. Figure 4 As shown in the figure, NCO is a numerically controlled oscillator that generates a local carrier. The signal is then subjected to two-stage demodulation, which is software coherent demodulation, to obtain a hybrid time-domain signal.

[0058] Step 3, code detection, such as Figure 5As shown, the mixed time-domain signal obtained after two-stage demodulation is already a demodulated modulated signal, which contains 10 signals carrying different modulation frequencies. Therefore, based on the frequency bands of the 10 modulation frequencies, software radio technology is used to set narrowband filter banks with different thresholds to perform matched filtering on the mixed time-domain signal, separating each modulation signal. The 10 modulation frequencies carried in the mixed time-domain signal are obtained through filtering, and radio correction command symbols are obtained through frequency mapping coding detection.

[0059] Step 4, error detection, such as Figure 6 As shown, an error matching algorithm is employed. The code elements obtained from the encoding detection are sorted and combined to obtain the radio correction command. This is then matched against the standard radio correction command for error matching. The results are statistically analyzed, and the ratio of the number of errors to the total number of detections is the bit error rate. Since all radio correction commands for intermittent radar radiation signals are collected and stored, the location of the errors within the entire cycle can be determined simultaneously when calculating errors, allowing for a judgment between sporadic occurrences and equipment malfunctions.

[0060] It should be noted that the above description is merely illustrative and explanatory of the present invention. Those skilled in the art should understand that any modifications and substitutions to the present invention fall within the scope of protection of the present invention.

Claims

1. A method for detecting radio correction command errors in directly sampled IQ signals, characterized in that, The radio correction command error detection method for the direct radio frequency sampled IQ signal includes the following steps: Step 1: Directly acquire I and Q signal data from the radio frequency signal, perform digital processing, and store the data in the IQ data storage module; Step 2: Read the I and Q signal data, and obtain the mixed time-domain signal through two-stage demodulation; Step 3: Encode and detect the mixed time-domain signal to obtain radio correction instruction symbols; Step 4: Perform a matching operation between the radio correction command symbols and the standard radio correction command error codes to achieve error detection and error location; Step 2 specifically includes the following steps: Step 21: Read the IQ data from the IQ data storage module, and obtain the baseband envelope signal by performing a sum of squares operation on the I and Q signals; Step 22: The baseband envelope signal is low-pass filtered to obtain the load wave signal; Step 23: The load wave signal is demodulated in one stage to obtain a hybrid time-domain modulated signal; Step 24: Perform two-stage demodulation on the hybrid time-domain modulated signal to obtain the hybrid time-domain signal; In step 23, the first-level demodulation is phase demodulation. The phase demodulation adopts an orthogonal demodulation algorithm and uses software radio technology to process the orthogonal dual channels separately to obtain a hybrid time-domain modulated signal. In step 24, the secondary demodulation is software coherent demodulation, and a hybrid time-domain signal is obtained through software coherent demodulation. Step 3 specifically includes the following steps: Step 31: Set narrowband filter banks with different thresholds according to the modulation frequency of the mixed time-domain signal; Step 32: Perform matched filtering on the mixed time-domain signal to separate each modulation signal; Step 33: Obtain the modulation frequency carried in the mixed time domain signal by filtering, and obtain the radio correction instruction code through frequency mapping coding detection.

2. The method for detecting radio correction command errors in directly sampled IQ signals as described in claim 1, characterized in that, Step 1 specifically includes the following steps: Step 11: Feed the radio frequency signal from the antenna into the limiter; Step 12: The radio frequency signal after the limiter is passed through a low noise amplifier and narrowband filtering is performed to remove in-band and in-band interference signals. Step 13: After adjusting the gain of the variable gain amplifier, the magnitude of the RF signal is made to fall within the dynamic processing range of the ADC. Step 14: Perform anti-aliasing filtering using a bandpass filter; Step 15: The sample is sent to the ADC for bandpass sampling and digitization. Step 16: After digital processing, the signal is converted into baseband I and Q signals by digital down-conversion and filtering, and the I and Q data are stored in the IQ data storage module. The I and Q signals are a pair of phase-quadrature modulation signals.

3. The method for detecting radio correction command errors in directly sampled IQ signals as described in claim 1, characterized in that, In step 4, the radio correction command code elements and the standard radio correction command errors are matched using an error matching algorithm.

4. The method for detecting radio correction command errors in directly sampled IQ signals as described in claim 1, characterized in that, Step 4 specifically includes the following steps: Step 41: Obtain the radio correction instruction code elements obtained from the encoding detection by sorting and combining them to obtain the radio correction instruction; Step 42: Perform error matching calculation between the radio correction command and the standard radio correction command, and statistically analyze the verification results. The ratio of the number of errors to the total number of detections is the bit error rate. Since all radio correction commands are collected and stored, the location of the error in the entire cycle can be determined when calculating the bit error rate, which can be judged as an occasional occurrence or a device malfunction.

Images