A Three-level Symbol Offset Carrier Modulation Method Based on Time-Domain Raised Cosine Pulse

Abstract

The object of the present invention is to propose a kind of method based on time-domain raised cosine pulse three-level symbol offset carrier modulation, its realization process is as follows: at first determine spread spectrum code frequency fc, subcarrier frequency fsc, sine or cosine phase subcarrier modulation mode and The time-domain raised cosine pulse time width duty cycle ρ constructs a sub-carrier signal based on the time-domain raised cosine pulse three-level symbol sine or cosine phase. Then, the pseudo-random sequence is used to spread the navigation signal, and then the sub-carrier is modulated, and finally the obtained signal is modulated by the carrier of the orthogonal branch. The signal generated by this method is of constant amplitude, which can flexibly adjust the division degree of the main lobe and side lobe of the signal power spectrum, so that the navigation signal has good code tracking performance, anti-interference and anti-multipath capabilities, and compatibility with other system signals . At the same time, it avoids the occurrence of large-scale side lobes, improves the spectrum efficiency, and is especially suitable for satellite navigation services that use high-efficiency nonlinear amplifiers with limited power and bandwidth.

Description

Technical field: [0001] The invention relates to a method for realizing satellite navigation system signals, in particular to a three-level symbol offset carrier modulation method based on time domain raised cosine pulse. Background technique: [0002] The navigation signal system is in 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 band of the Global Navigation Satellite System (GNSS), and to further improve the ranging accuracy and anti-interference performance of the signal, new signal modulation methods are constantly emerging. Binary Offset Carrier (Binary Offset Carrier, BOC(n,m)) is a new modulation method that can meet the above requirements, in which the frequ...

AI Technical Summary

Problems solved by technology

The BOC modulation method given in the article will lead to a large-amplitude sidelobe outside the band and reduce the efficiency of the power amplifier, and the code tracking performance, anti-multipath and anti-interference ability of the signal are still not ideal. For the above shortcomings, the present invention proposes a time-based Domain Raised Cosine Pulse Three-levels Offset Carrier Modulation Method (Time Domain Raised Cosine Three-levels Offset Carrier, TDRC-TOC(n,m,ρ)), where the subcarrier signal can take values ​​of ±1 and 0, and ±1 The signal waveform is represented by a raised cosine pulse in the time domain. This method not only provides more options for the design of navigation signals, but also can effectively reduce the large side lobes of the power spectrum, reduce the interference to adjacent signals, and improve the accuracy of navigation signals. Power efficiency, while having better code tracking performance, anti-multipath and anti-jamming capabilities, is of great significance for improving the navigation and positioning capabilities of navigation systems

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