Pre-compensation method for offset frequency of low-orbit satellite mobile terminal

Abstract

The invention provides a pre-compensation method for offset frequency of a mobile terminal of a low-orbit satellite, and the method comprises the steps: a mobile terminal completes downlink carrier capturing and tracking through a strategy of frequency pre-compensation of a first-stage frequency synthesizer and temperature compensation of a second-stage crystal oscillator, and guarantees the baseband demodulation performance; meanwhile, an uplink carrier signal of a sending end is pre-corrected, and it is guaranteed that the carrier is at the nominal frequency when reaching a satellite; large and time-varying frequency deviation of uplink and downlink signals of the satellite-ground communication system can be compensated in real time; and the defect of temperature drift of the crystal oscillator can also be overcome, and relatively high frequency modulation precision can be achieved, so that a relatively good deviation correction effect can be achieved even if the mobile terminal works in a high-power state.

Description

technical field [0001] The invention belongs to the technical field of satellite communication, and in particular relates to a precompensation method for frequency offset of a low-orbit satellite mobile terminal. Background technique [0002] The satellite orbit height of the LEO satellite mobile communication system is low, and there is obvious relative motion between the satellite, the mobile terminal and the gateway station, resulting in a large relative radial velocity, which will make the uplink and downlink signals of the satellite-ground communication system appear large and time-varying The frequency offset and other dynamic characteristics of the communication link cause the signal on the communication link to have high dynamic characteristics such as Doppler frequency shift and its large change rate, large amplitude change, and variable transmission delay; especially for high dynamic terminals, This change is more drastic. The Doppler effect will seriously affect ...

AI Technical Summary

Problems solved by technology

[0004] In view of the problems existing in the prior art, the present invention improves the poor real-time performance of frequency compensation in the traditional classic compensation scheme, and cannot effectively correct the frequency offset problem caused by the crystal oscillator, and proposes a pre-compensation method for the frequency offset of the low-orbit satellite mobile terminal, including the following steps :

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