A Carrier Frequency Offset Estimation Method for GFSK System

Abstract

The invention relates to a carrier frequency offset estimation method used in GFSK system. In this method, low-pass filtering is performed first, and the filtered signal is segmented for automatic frequency offset compensation. The compensated signal is filtered by a differential phase detector and Gaussian filter to obtain a smoothed baseband symbol waveform; for the baseband signal with superimposed frequency offset The waveform is filtered by segmented average value to estimate the residual DC; and then the residual frequency offset value is obtained through the mapping relationship between DC and frequency offset; the residual frequency offset value is fed back to automatic frequency offset compensation after frequency offset accumulation and threshold judgment, and the frequency offset compensation is updated value. When the accumulated frequency offset value exceeds the set threshold, the frequency offset value is set to a preset value. The frequency offset estimated by the invention has a large range, and at the same time, the convergence speed of the frequency offset estimation is fast, and has the characteristics of low power consumption.

Description

technical field [0001] The invention relates to the field of wireless communication, in particular to a method for estimating carrier frequency offset in GFSK system. Background technique [0002] In wireless communication, due to the different crystal oscillator deviations of the transmitter and receiver, the carrier frequency deviation is introduced. If the carrier frequency offset is not handled properly, the accuracy of demodulation will be reduced, resulting in loss of system performance. GFSK (Gaussian Frequency Shift Keying) is a modulation method suitable for low-rate short-distance wireless communication. It has the characteristics of compact signal spectrum, good bit error characteristics, and low power consumption. [0003] The existing methods usually estimate the DC, convert the DC to a frequency offset value through a lookup table, and then compensate, such as patent [201410686680.7]. This method has two shortcomings. The first is to look up the frequency offs...

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Problems solved by technology

[0003] The existing methods usually estimate the DC, convert the DC to a frequency offset value through a lookup table, and then compensate, such as patent [201410686680.7]. This method has two shortcomings. The first is to look up the frequency offset value through a lookup table. The offset accuracy is not high, and the residual frequency offset is large, which affects the demodulation performance of the system; secondly, a wide range of frequency offset values ​​cannot be tolerated. When the frequency offset value is large, only the preamble is used for DC estimation at this time, and the estimation is not accurate at this time

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