Demodulation method and device of D8PSK (differential 8-ary phase shift keying) modulation signals of VDL (VHF (very high frequency) digital link) communication system

Abstract

The invention relates to demodulation method and device of differential 8-ary phase shift key (D8PSK) modulation signals of a VHF (very high frequency) digital link (VDL) communication system. Aiming at the defects of the prior art, by combining with high-speed operation property of the current low-cost FGPA (field programmable gate array) element, the invention discloses demodulation method and device of D8PSK modulation signals of a VDL communication system. Under the premise of meeting the VDL physical layer link specification, the invention can greatly improve real-time of digital signal processing and lower the computation complexity as well as ensure the performance of a baseband demodulation system. By improving the sampling rate of baseband signals, fully utilizing interaction information contents of adjacent symbols brought by differential encoding and using the frequency difference estimation value of the last symbol as a frequency difference estimation value of the next symbol during the differential demodulation, and under the premise of meeting the VDL physical layer link specification, the invention can greatly improve the real-time of digital signal processing and lower the computation complexity.

Description

technical field [0001] The invention relates to communication technology, in particular to a method and device for real-time frequency difference correction and demodulation of a differentially encoded eight-phase phase-shift keying (D8PSK) modulated signal in a VHF Digital Link communication system. Background technique [0002] Because the D8PSK modulation signal occupies a small frequency bandwidth, the data communication rate is high, and the transmission bit error rate is low, it is widely used in communication, navigation and surveillance systems, especially in the fields of maritime affairs and air traffic control. [0003] figure 1 It is a schematic diagram of the transmission model of the VDL communication system. The intermediate frequency receiver receives the D8PSK intermediate frequency signal transmitted through the wireless channel, and restores the original data sent after digital down-conversion and baseband demodulation. The quality of the demodulation per...

AI Technical Summary

Problems solved by technology

[0010] The technical problem to be solved by the present invention is aimed at the deficiencies of the prior art, and in combination with the high-speed computing performance of today's low-cost FPGA devices, to provide a VDL communication system D8PSK modulated signal demodulation method and device, which meet the requirements of the VDL physical layer specification Under the premise, the real-time performance of digital signal processing can be greatly improved, the computational complexity can be reduced, and the performance of the baseband demodulation system can be guaranteed.

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