Data bit extracting method of mode S answering signal in ADS-B system

Abstract

The invention discloses a data bit extracting method of a mode S answering signal in an ADS-B (automatic dependent surveillance-broadcast) system. The method comprises a Gaussian noise power predicating step, a data bit division step, a data bit quality judging and high-quality data bit extraction step, a common-frequency interference maximum power calculation step, a low-quality data bit extraction step and a CRC error correction step. The data bit extracting method has the advantage that the anti-interference and high-fault-tolerance data bit extraction of the mode S answering signal of the ADS-B system is realized.

Description

technical field [0001] The invention relates to a method for extracting data bits of an S-mode response signal in an ADS-B system, which belongs to the signal decoding technology, and in particular relates to the data bit decoding technology of the ADS-B signal. Background technique [0002] Automatic Dependent Surveillance-Broadcast (ADS-B) is the main surveillance technology identified by ICAO in the future. Broadcast out at a certain interval to complete air surveillance and information dissemination. ADS-B expands the coverage of surveillance and increases the capacity of airspace, which is a safer and more efficient means of air traffic surveillance. [0003] Mode S is a new radar interrogation system that combines secondary surveillance radar (SSR) with a data link to support automated air traffic management. Mode S is an address selection system. Each inquiry contains an address, and only the corresponding aircraft responds. The frequency and format of the inquiry a...

AI Technical Summary

Problems solved by technology

In this method, when the signal is interfered by the same frequency, it is easy to have multi-location reliability of 0. In theory, if the number of data bits with a confidence of 0 exceeds 2, the error correction result will be unreliable, and if it exceeds 5, it will not be corrected. wrong

In the case that the signal is crosstalked by the A / C signal, if all the data bits are correctly extracted except for the part of the data bits covered by the crosstalk, that is, if the decoding error can be guaranteed to be within a 24-bit interval and the error bits do not exceed 12, then you can use An error correction algorithm (also known as a conservative error correction algorithm) is used for correction, but due to the influence of spike interference and Gaussian noise, this guarantee is difficult to establish when the signal-to-noise ratio is small, and the reliability of the error correction results will also be affected. Lower than normal error correction methods

[0005] Chinese invention patent application CN 103199944A provides a complete set of methods for S-mode signal header detection, reference power calculation, and data bit extraction. The performance is poor, and the disturbed data bits are easily judged as low confidence, and once the number of low confidence data bits exceeds 2, it is difficult to complete error correction through CRC check

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