A study on new secondary codes for GNSS

Recently, the GNSS signal has tended to utilize the data channel and the pilot channel, and the pilot channel uses a secondary code as well as a primary code. In general, a long secondary code is used for frame synchronization and a short secondary code is used for data symbol synchronization. So far, most of GNSS signals use NH code as the short secondary code. However, the NH code may decrease the ratio of the maximum peak to the side peak as the residual Doppler frequency increases. In this paper, we analyze the effect of residual Doppler frequency and propose a new secondary code candidate which has similar performance to NH code. Finally, the ratio of the maximum peak to the side peak according to the residual Doppler frequency is presented for each NH code and proposed secondary code candidate.