Combined modulation method of phase modulation and symmetrical raised cosine frequency modulation

Abstract

The invention provides a combined modulation method of phase modulation and symmetrical raised cosine frequency modulation. The combined modulation method comprises the following steps: generating waveform samples of four modulated signals which are orthogonal to each other, wherein two modulated signals are phase modulation signals and the other two modulated signals are symmetrical raised cosine frequency modulation signals; grouping binary information code elements to be modulated, wherein each adjacent three information code elements belongs to one group; selecting the waveform samples of the modulated signals according to the corresponding mapping relationship; and adding polarity to acquire the modulated signals. The modulated signals generated by the method have constant-amplitude waveform and have strong ability of resisting amplitude fading. The waveform samples of the modulated signals comprise the phase modulation signals and the symmetrical raised cosine frequency modulation signals, wherein the symmetrical raised cosine frequency modulation signals are non-linear frequency modulation signals and have strong ability of resisting interception.

Description

technical field [0001] The invention relates to a multi-ary system digital modulation method in the field of digital communication. Background technique [0002] In digital communication, Phase Shift Keying (PSK), as a phase modulation method, loads information by changing the phase of the carrier. Although the multi-ary phase modulation method has a greater ability to carry information, but the anti-noise ability is poor, the system performance is affected by the non-orthogonality between the constellation signals, and the demodulation performance is low. [0003] In order to solve the system performance using 8PSK (8-phase phase-shift keying) or 16PSK (16-phase phase-shift keying) modulation mode is affected by the non-orthogonality between constellation points, the system using QPSK (4-phase phase-shift keying) There is a problem of low capacity. The patent document with publication number CN 101588332A discloses a signal modulation and demodulation method combining cos...

AI Technical Summary

Problems solved by technology

[0004] However, the modulated signal waveform generated by the above-mentioned modulation method is not constant amplitude, which makes its anti-fading ability poor, the signal has a large peak-to-average ratio, and the power amplifier at the back end of the transmitter needs to have a large linear region

Moreover, the modulated signal waveform samples used are conventional phase-modulated signals and linear frequency-modulated signals, which makes the signal low in anti-intercept ability and not strong in confidentiality

Images