Carrier false-lock correction method

Abstract

The invention relates to a carrier false-lock correction method which utilizes the characteristic that codes and carrier wave frequency deviation have a proportional relationship due to a relative dynamic state. In the method, firstly, same-phase path I sampled signals and quadrature phase path Q sampled signals are sent to a code ring for phase discrimination, and then phase discrimination values output by the code ring are accumulated and are compared with thresholds computed through theoretical carrier wave false-lock frequency deviation values to obtain the direction and deviation value of the carrier wave frequency deviation, and then local carrier wave is subject to frequency compensation, so that the local carrier wave can rapidly and accurately find out carrier wave false lock situations under the condition of maintaining the tracking state, thereby greatly improving the success rate of carrier wave tracking.

Description

technical field [0001] The invention relates to a fast correction method for carrier tracking loop error locking. Background technique [0002] In order to overcome the impact of message data bit flipping on the carrier tracking loop, it is necessary that the phase detector of the carrier tracking loop is not affected by the 180-degree phase flipping. Therefore, the current satellite navigation receiver generally uses the Costas carrier tracking loop, so that the pre-detection integral When the time does not cross the data bit junction, the loop is not sensitive to the 180-degree phase reversal of the I and Q signals, but when there is a deviation in the capture frequency, the phase difference between the local carrier and the satellite signal carrier exceeds 180 degrees or the frequency difference exceeds Δf ( T is the pre-detection integration time), the tracking loop can often continue to keep track, but it will cause the data bits of the message to be reversed by mistak...

AI Technical Summary

Problems solved by technology

[0002] In order to overcome the impact of message data bit flipping on the carrier tracking loop, it is necessary that the phase detector of the carrier tracking loop is not affected by the 180-degree phase flipping. Therefore, the current satellite navigation receiver generally uses the Costas carrier tracking loop, so that the pre-detection integral When the time does not cross the data bit junction, the loop is not sensitive to the 180-degree phase reversal of the I and Q signals, but when there is a deviation in the capture frequency, the phase difference between the local carrier and the satellite signal carrier exceeds 180 degrees or the frequency difference exceeds Δf ( T is the pre-detection integration time), the tracking loop can often continue to track, but it will cause the data bits of the message to be reversed by mistake, resulting in the wrong extraction of the message

[0003] Existing methods often need to judge that the data bit has erroneously flipped during the bit synchronization and frame synchronization stages, and then re-capture the signal to solve this problem, which often affects the channel tracking speed and even the positioning speed

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