A carrier frequency traction method of dynamic BeiDou signal based on half-millisecond integration

In view of the problem that the frequency-lock loop is subject to frequent data transitions of BeiDou signal, which results in narrow frequency pull-in range and causes unlocking the signal tracking loop easily under dynamic situations, a carrier frequency traction method of dynamic BeiDou signal based on half-millisecond integration is proposed. Every millisecond the frequency-lock loop updates, and two adjacent pre-detection integration value pairs of half millisecond are extracted within the same data bit interval, and are discriminated by the four-quadrant arctangent discriminator to estimate the local carrier frequency error. Then, the error is filtered and used to control the numerically controlled oscillator to produce the corresponding local carrier and realize the carrier frequency traction with a wide pull-in range. Based on the dynamic BeiDou B3I signal, the results of actual vehicle experiment and high dynamic simulation indicate that the proposed method can not only eliminate the effect of data transitions on frequency lock loop, but also expand the pull-in range of carrier frequency traction to about four times of the traditional method (The dynamic sports car experiments verifyits effectiveness at 872.5Hz). Furthermore, the low complexity of the proposed method makes it easy to be applied in actual engineering scenes.