Precompensation method for in-band group delay fluctuation of satellite navigation signal generating system

Abstract

The invention relates to a precompensation method for in-band group delay fluctuation of a satellite navigation signal generating system, which comprises the following steps: (1) measuring a combined S parameter of a modulator, a filter and an amplifier in the satellite navigation signal generating system, and determining amplitude-frequency and group delay characteristic of the combination of the three devices; (2) counting the group delay characteristic of a precompensation filter according to the combined group delay characteristic; (3) obtaining the phase-frequency characteristic of the precompensation filter; (4) setting the phase-frequency characteristic of the precompensation filter to be an inverse Sinc function; (5) obtaining a system function of the precompensation filter according to the amplitude-frequency characteristic and phase-frequency characteristic of the precompensation filter; (6) obtaining a unit impulse response function of the precompensation filter; (7) setting a threshold value, and setting the quantity in the unit impulse response function, which is smaller than the threshold value, to be zero to be as a coefficient of the precompensation filter; and (8) realizing the precompensaiton filter in a digital standalone of the satellite navigation signal generating system by using the coefficient of the precompensation filter, so as to compensate the group delay fluctuation of the satellite navigation signal generating system.

Description

technical field [0001] The invention relates to satellite navigation technology, in particular to a precompensation method for in-band group delay fluctuation of a satellite navigation signal generation system. Background technique [0002] The satellite navigation signal generation system is composed of digital stand-alone, modulator, amplifier, filter and antenna. The digital stand-alone generates a digital baseband signal according to the agreed navigation signal format, and sends it to the modulator after digital-to-analog conversion; the modulator up-converts the analog baseband signal to generate a radio frequency navigation signal, and sends it to the amplifier; the amplifier amplifies the radio frequency navigation signal To the required power, broadcast to the ground through the antenna. [0003] During the generation of satellite navigation signals, the group delay fluctuations of modulators, filters and amplifiers seriously deteriorate the quality of the generate...

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Problems solved by technology

[0008] (1) Method 1 assumes that the group delay of each narrowband signal output by the comb wave filter is a fixed value, and then compensates it. If the bandwidth of the comb filter is wide, this method will cause a large compensation error; If the bandwidth of the comb filter is narrow, it will lead to increased complexity and cost;

[0009] (2) The feedback loop and calibration system of this method 2 are complex to implement and are not suitable for satellite navigation signal generation payloads

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