A Dynamic Threshold Acquisition Method for Judging the Confidence Degree of Ads-b Signal Demodulation Results

Abstract

The invention discloses a dynamic threshold acquisition method for judging the confidence degree of ADS‑B signal demodulation results, and relates to the field of communication signal processing. Aiming at the problem that the confidence threshold in the prior art demodulation method is a fixed value, the confidence judgment is not flexible enough, which affects the bit error rate. The present invention has the characteristics of higher consistency for the signal-to-noise ratio of all chips inside each frame message, fully utilizes the 8us sampling data of the header, and calculates the high-voltage average value x of the ADS-B header 1 and the overall mean x 2 then obtain the middle confidence threshold; the threshold size of the present invention is only related to the size of the value of the ADS-B signal header sampling point, after the current frame signal is processed, the size of the threshold α also changes according to the characteristics of a frame signal, The false positive rate of the dynamic threshold method is lower, especially in the case of low signal-to-noise ratio. The threshold α is only related to the signal itself, and has nothing to do with the structure of the receiver. It has a stronger adaptive ability and can reduce the bit error rate to a greater extent.

Description

technical field [0001] The invention belongs to the field of communication signal processing, and relates to a method for judging the confidence of digital signal demodulation, in particular to a method for obtaining a dynamic threshold value for judging the confidence of an ADS-B signal demodulation result. Background technique [0002] Automatic Dependent Surveillance-Broadcast (ADS-B) technology is a technology based on satellite positioning information for ground / air traffic control monitoring, Air-to-air surveillance technology. The ADS-B signal consists of a header and a message, such as figure 1 As shown, the length of the header is 8us, among which 0~0.5us, 1~1.5us, 3.5~4us, 4.5~5us are high level, other parts are low level; the message part is PPM code modulation. When performing PPM demodulation on the message, the method used is to compare the size of the sample value A of the first 0.5us and the sample value B of the last 0.5us of a symbol to judge, if A>=B dem...

AI Technical Summary

Problems solved by technology

[0011] 1. Whether it is a single-threshold scheme or a double-threshold scheme, the threshold is a fixed value, which has a strong relationship with the structural characteristics of the receiver and the test experience of the engineer. The confidence judgment of the signal is not flexible enough, which affects the bit error rate.

[0012] 2. Since the threshold is closely related to the receiver itself, if it is transplanted to other types of receivers, the threshold needs to be adjusted accordingly. Therefore, these solutions are not conducive to the development of multi-series products, and the debugging cost is high

Images