A low-complexity coarse carrier acquisition algorithm for signals with extremely low signal noise ratio and high dynamics

A improved carrier acquisition algorithm for signals with extremely low signal noise ratio and high dynamics is proposed. After padding extra zeroes to the signal, the algorithm shifts signal's frequency spectrum to compensate for the Doppler rate of carrier, which overcomes the high computational complexity in traditional time-domain matching-average periodogram algorithm. Its computational complexity decreases in proportion with the ratio of the number of matched branches against the quantity of zero padding, but without performance degradation. In addition, the design method of key parameters related to performance and complexity is also presented. Simulations are performed when the signal noise ratio (SNR) is -41 dB (carrier-to-noise ratio C/N₀ is 18 dBHz), Doppler frequency varies from -300 to 300 kHz, Doppler rate ranges from -800 to 800 kHz/s and data rate is 20 bps. The results show that the proposed algorithm reaches the same performance as the original algorithm does, with frequency accuracy being ±12 Hz, Doppler rate being ±25 Hz/s and acquisition probability being over 90%. The performance meets the demand of carrier tracking. The acquisition time of proposed algorithm increases by about 8% while its computational complexity decreases by 70% compared to the original algorithm.