Low noise GPS (Global Positioning System) carrier wave tracking method based on RSL (Recursive least square filter)

Abstract

The invention relates to a low noise GPS (Global Positioning System) carrier wave tracking method based on an RLS (Recursive least square filter). The low noise GPS carrier wave tracking method comprises the following steps of: measuring an instantaneous phase difference of a local carrier wave and a tracking satellite by a carrier wave tracking loop by utilizing a table look-up type second quadrant arc tangent phase discriminator; introducing the RLS to filter measurement noises; meanwhile estimating a frequency difference according to phase difference variation; utilizing the frequency difference and the phase difference as frequency discrimination input and phase discrimination input of a loop filter with a second order lock frequency loop assistant in a three-order phase locking loop; filtering by the loop filter to output a carrier wave control adjustment variable with high precision and low noise, and correspondingly adjusting carrier wave NCO (Numerical Control Oscillation) to control the local carrier wave so that a receiver keeps phases and frequencies of the local carrier and a tracking satellite carrier wave consistent. In the invention, the low noise GPS carrier wave tracking method based on the RSL ensures that the GPS carrier wave tracking loop can work stably under the condition of low signal to noise ratio and certain dynamic state, keeps the phase not to overturn or skip cycles and ensures the carrier wave tracking precision.

Description

technical field

[0001] The invention relates to a low-noise GPS carrier tracking method, in particular to an RLS-based low-noise GPS carrier tracking method. Background technique

[0002] For GPS receivers, the acquisition, tracking, and demodulation of satellite signals are the basis of positioning and navigation, and one of its key technologies is the design of carrier tracking loops. The purpose of the carrier tracking loop is to try its best to keep the copied carrier signal consistent with the received satellite carrier signal, so as to completely strip the carrier of the satellite signal through the frequency mixing mechanism. If the copied carrier is inconsistent with the received carrier, the carrier in the received signal cannot be completely stripped, that is to say, the received signal cannot be down-converted to a real baseband signal, which affects the correct extraction of navigation message data bits. In addition, if the consistency between the copied carrier...

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