Joint synchronization method for Viterbi demodulation of GFSK (Gaussian Frequency Shift Keying) signal

Abstract

The invention provides a joint synchronization method for Viterbi demodulation of a GFSK (Gaussian Frequency Shift Keying) signal, which comprises the following steps of: performing joint action on symbol bit correlation of a baseband signal before Viterbi demodulation and bit correlation after demodulation, and judging the sizes of two correlation values in real time to finish bit synchronization. And the receiving sampling point data participating in calculation of the branch path during demodulation comes from one information code, so that the accuracy of branch metric calculation during Viterbi demodulation is ensured. Compared with the method only adopting the synchronization before demodulation, the method adopting the joint synchronization before and after demodulation can avoid the problem of error synchronization caused by false correlation peak appearing in the synchronization before and after demodulation.

Description

technical field [0001] The invention relates to the technical field of bluetooth communication, in particular to a synchronization algorithm applied in Viterbi demodulation of GFSK signals. Background technique [0002] Gaussian frequency shift keying (Gaussian Frenqueny Shift Keying, GFSK) is to limit the spectral width of the signal through a Gaussian low-pass filter before modulation to improve spectral efficiency. The modulation method has the advantages of constant envelope, small out-of-band radiation, and fast decay rate of power spectrum side lobes. It is widely used in wireless communication systems such as Bluetooth transmission and digital enhanced cordless phones. [0003] Among the current demodulation methods for GFSK signals, differential demodulation is more common. Its structure is simple and easy to implement in circuit, and it is not sensitive to frequency difference, but its bit error performance is poor. It is relatively high, resulting in high transmit...

AI Technical Summary

Problems solved by technology

During Viterbi demodulation, it is necessary to calculate the cumulative metric value and the branch metric value, where the branch metric value is obtained by correlating the received baseband signal with the theoretical baseband signal, so it must be ensured that the received baseband signal and the theoretical The sample point values ​​of the baseband signal are in one-to-one correspondence, that is, they come from the sampling of a complete symbol, otherwise, among all the paths calculated during Viterbi demodulation, there will be no path that completely matches the received signal, and the demodulation performance will be poor. It will be greatly reduced or even completely impossible to demodulate

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