A signal processing method suitable for high-sensitivity spaceborne ads-b receiver

Abstract

The invention relates to a signal processing method suitable for a high-sensitivity space-borne ADS-B receiver, belonging to the field of aviation surveillance technology, including S1: the ADS-B signal received by the antenna is demodulated by radio frequency to obtain an intermediate frequency signal, and the digital signal after digital-to-analog conversion Down-conversion demodulation to obtain digital baseband signals; S2: low-pass filtering: preliminary filtering of out-of-band noise; S3: coarse synchronization detection, extracting coarse synchronization signal segments; S4: coarse frequency / phase offset estimation and compensation; S5: raised cosine filtering Device: improve signal-to-noise ratio; S6: fine synchronization detection, extracting fine synchronization signal segment; S7: non-coherent demodulation, if it passes the verification, then output ADS-B message; if not, then implement step S8; S8: carry out Precise frequency / phase offset estimation and compensation, and coherent demodulation, if the verification is passed, an ADS‑B message will be output; if it fails, the data will be discarded. The method has high detection rate, low false alarm rate and high decoding success rate.

Description

technical field [0001] The invention belongs to the technical field of aerial surveillance and relates to a signal processing method suitable for a high-sensitivity space-borne ADS-B receiver. Background technique [0002] Due to the long distance between the satellite and the aircraft, the ADS-B signal is weak and the signal-to-noise ratio is low. After calculation, the minimum signal power to be processed is -102dBm, and the decoding rate must reach more than 90%. A high-sensitivity spaceborne ADS-B receiver is required. , while the ground-based ADS-B receiver can only process signals with a minimum power of -90dBm, and the signal processing method is not applicable. The signal processing of the existing space-borne ADS-B receiver is aimed at the characteristics of the satellite-based ADS-B receiver, and the signal processing method of the ground-based ADS-B receiver is improved, but it does not meet the sensitivity requirements and cannot complete the coverage of the rece...

AI Technical Summary

Problems solved by technology

The traditional land-based receiver ADS-B signal signal processing method is as attached figure 1 As shown, the Mode S 1090MHz ADS-B signal received by the antenna is demodulated to obtain an intermediate frequency signal, and after digital-to-analog conversion, the digital baseband signal is obtained through digital down-conversion demodulation, and then the frame header is implemented after low-pass filtering to filter out-of-band noise. The detection is synchronized. The frame head detection here is based on the method of pulse edge, pulse shape and pulse power. However, under spaceborne conditions, the pulse distortion is large. Under this method, the detection rate cannot meet the sensitivity requirements of the spaceborne ADS-B receiver. After frame header detection, bit judgment and confidence extraction are performed. The bit judgment adopts the center comparison method, which uses less information, and then performs CRC error detection on the message bits after the bit judgment without error correction. However, under spaceborne conditions, there are many error bits. , it is necessary to perform effective error correction to improve the decoding rate. If the CRC is correct, the message is successfully decoded. If the verification is wrong, the message is discarded.

The traditional ground-based receiver ADS-B signal processing flow is simple, the amount of calculation is small, and it does not consider the use of coherent demodulation to improve sensitivity, and it cannot complete the decoding of weak signals under spaceborne conditions

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