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Modulation and demodulation method for continuous phase signals

A demodulation method and phase modulated signal technology, applied in the field of continuous phase signal modulation and demodulation, can solve problems such as difficulty in practical use and performance deterioration.

Inactive Publication Date: 2010-01-27
XIDIAN UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method is coherent demodulation, which is very sensitive to the frequency difference between the transmitting and receiving carriers, and requires the receiver to have a carrier recovery circuit
If the transmitting and receiving carriers are not exactly the same frequency and phase, the performance will deteriorate sharply and it will be difficult to be practical

Method used

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  • Modulation and demodulation method for continuous phase signals
  • Modulation and demodulation method for continuous phase signals
  • Modulation and demodulation method for continuous phase signals

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Embodiment Construction

[0070] The implementation process of the present invention will be described in detail below in conjunction with the accompanying drawings.

[0071] The modulation and demodulation method of the present invention can be realized by hardware circuit, and also can be conveniently realized by software of signal processor. In this embodiment, a raised cosine CPM signal with M=8, h=1 / 8, and a length of 2T is used. The modulation and demodulation of the CPM signal is realized by the software mode of the signal processor.

[0072] (1) Formation of modulation waveform

[0073] First, decompose the phase φ(t, α) of the raised cosine CPM signal into two items: the first item is the phase state θ n , the second term is the associated state α n ={α n-1 , α n-2 ,...,α n-L+1} and the current symbol α n Determined phase increment θ(t, α). When K is an even number, θ n There are P values, {0, πK / P, 2πK / P, ..., π(P-1)K / P}; when K is an odd number, θ n There are 2P values. In this ex...

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Abstract

Being adopted for modulation method in the invention, waveform storing quadrature modulation includes steps: decomposing Phase Phi(t, Alpha) to Thetan and Theta (t, Alpha); building a corresponding look up table, storing their sine value and cosine value; through look up table to obtain sine value and cosine value of Thetan and Theta (t, Alpha); then through difference operation to obtain baseband signal. Being adopted for demodulation method in the invention, simplified noncoherent viterbi algorithm simplifies state of CPM signal as Sigman'; receiver processes the intermediate frequency signal to obtain complex baseband signal GammaB (t); the baseband signal multiplied by a delayed and shifted signal obtains baseband differential signal; according to grid chart, calculating branch measure of each state Sigma n+1'; then estimating not simplified ML state Sigma' n+1 (Sigma' n+1), and tracing back to output code element. Features are: easy of calculation and implementation and robustness.

Description

technical field [0001] The invention belongs to the technical field of communication, and relates to modulation and detection in digital communication, in particular to a modulation and demodulation method of a continuous phase signal, which can be used in the fields of mobile communication, satellite communication, deep space communication and remote measurement. Background technique [0002] In many application fields of existing communication systems, it is often required to maintain stable high-speed data communication under harsh communication environments, such as mobile, multipath, and dynamic changes. In this case, an efficient coding and modulation system is required to adapt to it. The design of the communication system should be able to achieve the following goals, for example, higher spectral efficiency greater than 2bits / sec / Hz; lower out-of-band power to reduce adjacent channel interference; good anti-interference performance; constant modulation signal envelop...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L27/18
Inventor 孙锦华李建东金力军
Owner XIDIAN UNIV
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