Carrier Doppler frequency offset capturing method for low signal-to-noise ratio and high dynamic scene

Abstract

The invention discloses a carrier Doppler frequency offset capturing method oriented to a low signal-to-noise ratio and a high dynamic scene, which can solve the problem of energy diffusion caused bylong-time signal accumulation in the low signal-to-noise ratio and the high dynamic scene. The method comprises the following steps: sequentially carrying out de-spreading processing on received L spread spectrum code element signals; performing fast Fourier transform on each code element signal; carrying out incoherent accumulation on the L code element signals to obtain an accumulation result; selecting Nc elements from the accumulation result to form a new set; calculating a clustering termination parameter; performing condensation hierarchical clustering on the elements in the set to obtain a plurality of clusters; calculating the size of each cluster; searching a maximum cluster from all the clusters; calculating an average value of serial numbers of all elements in the maximum cluster; and obtaining a Doppler frequency offset capture result according to the average value. According to the method, multiple signal elements are clustered into one cluster through clustering, diffusedsignal energy is accumulated again, accumulation gain is improved, and therefore the Doppler capture probability is effectively improved.

Description

technical field [0001] The invention relates to a carrier Doppler frequency offset acquisition method for scenes with low signal-to-noise ratio and high dynamics, and belongs to the field of space communication. Background technique [0002] With the development of aerospace technology, the flying distance of spacecraft is getting farther and farther, even beyond the scope of the solar system, and the flying speed of spacecraft is getting faster and faster. Therefore, aerospace communication faces the following two problems: (1) The increase of the communication distance will cause a large path loss, thereby seriously reducing the signal-to-noise ratio of the received signal; / s) and high acceleration (up to hundreds of g, g=9.8m / s 2 ) movement makes the carrier frequency of the signal produce a large Doppler frequency shift. In order to recover the signal, the carrier demodulation at the receiving end must compensate for the Doppler frequency offset. The key to compensat...

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Problems solved by technology

[0005] Aiming at the deficiencies in the prior art, the purpose of the present invention is to provide a carrier Doppler frequency offset acquisition method for low signal-to-noise ratio and high dynamic scene, to Solve the problem of low acquisition probability of Doppler frequency offset existing in the prior art

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