New system satellite signal NH code stripping method

Abstract

The invention belongs to a new system satellite signal NH code stripping method. The method includes the following steps of: dividing the capture into two stages: pre-capture and full-bit capture; inthe pre-capture stage, carrying out a round of full-range search on the frequency and code phase of a satellite navigation signal of which the length is a pseudo-code period by using a parallel frequency search algorithm; and then, in the full-bit capture stage, adjusting the phase of locally cached data according to an accurate code phase capture result, performing correlation operation on everyadjacent two pseudo-code periods in a satellite navigation signal of which the length is an NH code period, judging whether NH symbol hopping exists between the adjacent two pseudo-code periods according to a correlation operation result, and if the result of each judgment is the same as the assumed NH code sequence hopping rule, adding 1 to the counting variable of a TONG detector of the corresponding code sequence, and if different, subtracting 1 from the corresponding counting variable, and further determining that the NH code sequence hopping sequence corresponding to the TONG detector that first reaches the upper limit of counting is the hopping sequence of NH symbols in the detected satellite navigation signal. The advantages are that through the pre-capture and the full-bit capture,the ambiguity of frequency capture can be eliminated, the coarse synchronization of the NH code can also be realized, the problem that the satellite navigation signal is affected by the NH code in atracking stage and cannot adopt the pre-testing integral time longer than 1ms and a four-phase inverse tangent phase discriminator can be solved, and the tracking requirements of high-sensitivity loops can be adapted.

Description

technical field [0001] The invention belongs to a signal processing method of a satellite navigation receiver, in particular to a new-system satellite signal NH code stripping method. Background technique [0002] At present, the Beidou system adopts navigation message, Neumann-Hoffman (NH) code, and pseudo code synchronous modulation at the B1I frequency point. The original bit rate of the satellite navigation message is 50bit / s, and the data bit rate after NH code modulation is 1000bit / s. A data bit flip may occur every pseudocode cycle. NH code modulation will also be widely used in new system satellite signals. This improvement has advantages and disadvantages. On the one hand, the addition of NH code can improve the ability to resist narrow-band interference and improve the cross-correlation characteristics between satellite navigation signals; on the other hand, The existence of NH code will also lead to the ambiguity of frequency acquisition, and the length of integr...

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Problems solved by technology

NH code modulation will also be widely used in new system satellite signals. This improvement has advantages and disadvantages. On the one hand, the addition of NH code can improve the ability to resist narrow-band interference and improve the cross-correlation characteristics between satellite navigation signals; on the other hand, The existence of NH code will also lead to the ambiguity of frequency acquisition, and the length of integration time of tracking pre-check is limited, which affects the tracking accuracy

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