A novel high precision Doppler frequency estimation method based on the third-order phase-locked loop

In deep space exploration, many engineering and scientific requirements require the accuracy of the measured Doppler frequency to be as high as possible. In our paper, we analyze the possible frequency measurement points of the third-order phase-locked loop (PLL) and find a new Doppler measurement strategy. Based on this finding, a Doppler frequency measurement algorithm with significantly higher measurement accuracy is obtained. In the actual data processing, compared with the existing engineering software, the accuracy of frequency of 1 second integration is about 5.5 times higher when using the new algorithm. The improved algorithm is simple and easy to implement. This improvement can be easily combined with other improvement methods of PLL, so that the performance of PLL can be further improved.