GMSK (Gaussian Filtered Minimum Shift Keying) coherent demodulation method capable of rapidly overcoming Doppler shift

Abstract

The invention discloses a carrier recovery and clock synchronization method of a GMSK (Gaussian Filtered Minimum Shift Keying) signal capable of rapidly overcoming Doppler shift. The method comprisesthe design of a squaring loop as the main structure of a simple receiver. A phase discriminator module, a loop filter module and a digital voltage controlled oscillator module are included. At the same time, in order to increase the locking speed, the carrier frequency of the GMSK signal is estimated to obtain rough carrier frequency, and then a phase-locked loop is used for locking, thereby effectively shortening the locking time and improves the stability of a locked output signal at the same time. Through adoption of the improved squaring loop structure disclosed by the invention, the accuracy of phase error acquisition is increased, and the phase-locked loop works more stably. The method is applied to the fields of spaceflight test control and deep space communication, and can well meet the communication demand standard.

Description

Technical field [0001] The invention relates to the technical field of deep space communication, in particular to a GMSK coherent demodulation method that quickly overcomes Doppler frequency shift. Background technique [0002] In recent years, my country’s aerospace industry has developed by leaps and bounds, and the requirements for aerospace communications have become higher and higher, including the increase in communication data rates and the widening of communication frequency bands. This has also brought about a very significant problem that the frequency band resources are limited. Unrestrictedly increasing the spectrum width of the communication signal will also cause the degradation of signal transmission quality. Taking into account the contradiction between limited communication spectrum resources and people's increasing communication capacity, future modulation methods will develop in the direction of having good spectrum characteristics and higher bandwidth efficienc...

AI Technical Summary

Problems solved by technology

[0005] In deep space communication and aerospace measurement and control, the coherent demodulation of Gaussian minimum shift keying (GMSK) modulated signals also faces a problem, that is, due to the high-speed relative motion of the GMSK signal in the transmission between the aircraft and the ground receiver, it will cause Doppler The appearance of Le frequency shift, which greatly affects the demodulation effect

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