Design of GNSS carrier loop base on adaptive gain control

A novel structure of GNSS carrier loop based on Adaptive Gain Control (AGC) is given, and the loop is applied to track carrier frequency under high dynamic and low signal-to-noise ratio (SNR) conditions. It is found that adjusting the gain of error adjustment (GEA) of carrier loop can influence the loop bandwidth, so as to give consideration to both dynamic and stable characteristics. So a mathematical model which can adaptively adjust the loop gain according to the frequency discrimination results is proposed and tested for the loop tracking ability under GNSS software carrier platform. The test results indicate that the model can lock signals quickly with larger frequency jitter, can improve the frequency stability of tracked output signals, and can effectively reduce the impact of faulty control.