Offset carrier wave modulation method based on time domain raised cosine pulse generalization

Abstract

The invention discloses an offset carrier wave modulation method based on time domain raised cosine pulse generalization. The realization process is as follows: first of all, a spread spectrum code period, a subcarrier period, a sine or cosine type subcarrier modulation mode and time domain raised cosine pulse waveform variable parameters are determined, a sine or cosine phase subcarrier modulated waveform based on the time domain raised cosine pulse generalization is constructed, then, spectrum spreading is performed on navigation signals by use of a pseudo random sequence, subcarrier modulation is then carried out, and finally, carrier wave modulation of orthogonal branches is performed on obtained signals. According to the invention, the generated signals are constant in amplitude, the splitting degrees of main lobes and sidelobes of a signal power spectrum can be flexibly adjusted, and the navigation signals are enabled to have good code tracking performance, an anti-interference and anti-multipath capability and a capability of being compatible with other system signals. At the same time, large-amplitude sidelobes are prevented, the efficacy of a frequency spectrum is improved, and the method is especially suitable for satellite navigation service which employs an efficient nonlinear amplifier and has limited power and bandwidth.

Description

Technical field [0001] The invention belongs to the field of satellite navigation system signal modulation, and in particular relates to an offset carrier modulation method based on the generalization of time-domain raised cosine pulses. Background technique [0002] The navigation signal system is at the most critical position in the top-level design of the satellite navigation system. Its performance directly determines the navigation and positioning performance of the system. Navigation signal modulation is the most important thing in the design of the navigation signal system. In order to enable multiple signals to better share the limited frequency bands of the Global Navigation Satellite System (GNSS), and to further improve the signal's ranging accuracy and anti-interference performance, new signal modulation methods continue to appear. Binary Offset Carrier (BinaryOffset Carrier, BOC(n, m)) is a new modulation method that can meet the above requirements. The spreading cod...

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