Unambiguous tracking method for high-order BOC modulation navigation signal

Abstract

The invention discloses an unambiguous tracking method for a high-order BOC modulation navigation signal. The unambiguous tracking method comprises the following steps: counting operation periods of subcarriers; a variable-subcarrier half-cycle counting accumulated value Accsc is increased, and initialization is carried out; counting the counting difference of the subcarrier half-cycle counts Cnt2sc of the two FTF time mark signals as an incremental quantity, and accumulating the Accsc; continuously comparing the Accsc with the updated half-cycle fuzzy value Cntsc of the subcarrier; setting a locking state; if continuous equal times reach a lock-in threshold value, entering a lock-in state, replacing an original subcarrier half-cycle fuzzy value Cntsc with Accsc, and outputting a subcarrier observation value as a distance measurement observation value; setting a lock losing state; and if continuous unequal times reach a lock losing threshold value, entering a lock losing state, re-initializing the Accsc, and at the moment, outputting a code observation value as a distance measurement observation value. According to the method, the problem that traditional subcarrier tracking is fuzzy is solved, a good anti-multipath effect and stable high-precision distance measurement observed quantity can be obtained, and therefore the positioning precision is improved.

Description

technical field [0001] The invention relates to the field of satellite positioning and navigation, in particular to an unambiguous tracking method for high-order BOC modulated navigation signals. Background technique [0002] Modern satellite navigation systems generally use BOC modulation signals. Compared with traditional BPSK modulation, they can be transmitted on the existing carrier frequency without affecting the existing BPSK modulation signals. At the same time, the BOC modulated signal can obtain better anti-multipath effect and higher ranging accuracy. The high-order BOC factor carrier rate is high, the advantage is that it can obtain higher ranging accuracy, and the disadvantage is that there are multiple peaks in the correlation, which leads to unstable ranging accuracy. High-order BOC modulation signals have been applied in existing navigation systems. Beidou navigation system has BOC (14, 2) navigation signals at B1 frequency point, and Galileo has BOC (15, 2....

AI Technical Summary

Problems solved by technology

It is often possible that the accuracy of the code loop or subcarrier loop measurement is not enough, resulting in the phenomenon that the subcarrier half cycle ambiguity value Cnt_sc is more than 1 or less than 1

For the BOC(15,2.5) signal, there will be an error of about 9.7 meters, which will eventually lead to positioning errors

Images