A three-way Doppler measurement method for deep space probes based on prior models

Abstract

The present invention provides a three-way Doppler measurement method for a deep space detector based on a priori model, comprising: 1. establishing an expression of the downlink station receiving signal Sig_down(t); 2. according to the priori of the detector The orbit and the geographical coordinates of the uplink and downlink stations establish a priori optical travel time model τgeo(t); 3. According to the priori optical travel time model τgeo(t) and the transmission frequency f0 of the uplink station, the model for receiving signals at the downlink station is constructed Signal Sig_mod(t) and model frequency fmod(t); 4. Conjugate multiplication of model signal Sig_mod(t) and downlink station receiving signal Sig_down(t) to obtain compensation signal sig*(t); 5. The compensation signal sig*(t) is subjected to subsection integral filtering; 6. Utilize a phase-locked loop to track the filtered compensation signal sig*(t) to estimate its residual frequency Δf(t); 7. According to the residual frequency Δf( t) and the model frequency to obtain the three-way Doppler frequency f(t). The present invention removes the relatively large Doppler frequency through a smooth prior optical travel time model, only needs to measure a small residual frequency, easily realizes filtering, and can obtain high-precision Doppler frequency.

Description

technical field [0001] The invention relates to the technical field of Doppler frequency measurement, in particular to a three-way Doppler measurement method for a deep space probe based on a priori model. Background technique [0002] Deep space exploration refers to the exploration of breaking away from the gravitational field of the earth and entering the space of the solar system and space. It mainly includes two aspects of measurement: one is to conduct in-depth exploration of various planets and comets in the solar system, and the other is to conduct in-depth exploration of the Milky Way outside the solar system and even the entire space. The exploration of the universe. The Doppler effect refers to the phenomenon that when the wave source and the observer are in relative motion, the frequency of the wave received by the observer is not the same as the frequency emitted by the wave source. Three-way Doppler means: the uplink station on the ground transmits a stable si...

AI Technical Summary

Problems solved by technology

However, this method has the following disadvantages: (1) Since the signal received by the detector contains the main carrier, the ranging modulation signal, etc., in order to separate the main carrier from the ranging modulation signal, the filter used in this method must be a high-order Filters, such as the 50-order, 100-order, and 1000-order filters described in the literature, but it should be understood that the higher the order, the greater the amount of calculation; (2) When the Doppler frequency changes quickly (such as 1s changes 50Hz, 5s change 250Hz), the bandwidth of the filter is required to be no less than 250Hz, which limits the filtering effect; (3) The longer the integration time, the wider the spectrum of the Doppler signal due to Doppler broadening, which is not easy to measure, that is, it cannot Output frequency measurement value for any integration time

However, in order to avoid phase ambiguity, the constructed reference model is only suitable for "a certain period of time" (usually 1-10s), which is determined by the motion speed of the detector, but under the premise of not using the initial light line time , this period of time can only be guessed, making the system unstable, and this method cannot output the frequency of any integration time

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