Method for realizing GMSK (Guassian Minimum Shift Keying) signal generator based on FPGA (Field Programmable Gate Array)

Abstract

The invention relates to a method for realizing a GMSK (Guassian Minimum Shift Keying) signal generator based on an FPGA (Field Programmable Gate Array), which comprises the following steps: integrating an NRZ (Non-Return-to-Zero) coding module, a Gaussian filter module, a phase accumulation module, an orthogonal modulation module and a D / A (Digital to Analog) conversion module on an FPGA chip, filtering through NRZ coding and filtering mode selecting, accumulating a filtered signal into a phase value, carrying out two paths of ROM (Read Only Memory) table look-up on the phase value, multiplying a cosine value of one of the two paths by a coswt signal, multiplying a sine value of the other path by a sinwt signal and taking a difference between products of the two paths of signals as a generated GMSK modulation signal. The method has the beneficial effects that the signal modulated by the GMSK signal generator, which is realized by adopting the method, can select a filter with different filtering modes through flexibly controlling the switching of the filtering modes according to the filtering requirements of a system to realize the generation of a GMSK signal with different system bandwidth demands; and moreover, the method has the characteristics of high realization speed and less resources occupied, thereby satisfying the demand that the digital information processing system realizes the full digitalization of the GMSK signal generator.

Description

technical field [0001] The invention relates to a digital signal processing system in the communication field, in particular to a method for realizing a GMSK signal generator based on FPGA. Background technique [0002] Digital filters are usually applied to modify or change the properties of signals in the time domain or frequency domain. The most common digital filter is the linear time invariant (LTI) filter. According to the time characteristics of the unit impulse response h(n), LTI digital filters can be divided into two types: infinite unit impulse response (IIR) digital filter and finite unit impulse response (FIR) filter. [0003] The FIR (Finite Impulse Response) filter is the most basic component in a digital signal processing system. It can achieve arbitrary amplitude-frequency characteristics while ensuring strict linear phase characteristics. At the same time, its unit impulse response is limited and is not input to The output feedback stabilizes the system. ...

AI Technical Summary

Problems solved by technology

[0006] GMSK signal generators are generally implemented by analog filters and voltage-controlled oscillators, but the implementation of analog circuits has low flexibility, and parameter configuration needs to be realized by changing off-chip hardware parameters

Due to the development of all-digital communication systems, analog or analog-digital mixed GMSK signal generators can no longer meet the modernization needs of communication systems. Therefore, it is necessary to explore a new method for GMSK signal generators to realize full digitalization.

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