Analysis to the effects of NH code for Beidou MEO/IGSO satellite signal acquisition

The performance of Beidou MEO/IGSO satellite signal acquisition is greatly affected by the secondary code, the NH (Neumann-Hoffman) codes with possible bit sign transition in every millisecond modulated on the signal, which puts a limitation on the coherent integration duration. This paper address the problem of coherent integration over periods longer than one primary code length and the acquisition of secondary code chip position. A unique code sequence method applied in FFT-based model is proposed which can handle both these problems together.