Fast GNSS signal acquisition with Doppler frequency estimation algorithm

Abstract

In both urban and indoor environments, position and navigation technologies that are based on global navigation satellite systems (GNSSs) high requirements for acquisition sensitivity of a GNSS receiver. To increase the acquisition speed and sensitivity of a GNSS receiver, a new method called improved acquisition algorithm with Doppler frequency compensation (IAADFC) is proposed to realize a long coherent integration time (CIT) acquisition algorithm to increase the sensitivity of a GNSS receiver. Its CIT can be larger than the bit length of the navigation message. Based on the parameter estimation theory, the Doppler frequency estimation algorithm (DFEA) is proposed to reduce the Doppler frequency search range (DFSR) to speed-up the acquisition process. Then, the data bit sign transition (DBST) algorithm is proposed to remove the impact of the data bit sign transition to improve acquisition sensitivity. Then, the IAADFC is discussed. Simulation results demonstrate that the IAADFC can improve the sensitivity and speed of weak GNSS signal acquisition. Finally, we provide a detailed comparison between the proposed IAADFC algorithm and the non-coherent integration (NCI) algorithm. Simulation results shown demonstrate that our IAADFC algorithm can detect weaker signals than the NCI algorithm can. This can help meet the high sensitivity requirement for indoor and outdoor seamless position and navigation service.