Method and apparatus for clock recovery

Abstract

The invention discloses a method and a device for recovering clocks, wherein the method comprises: receiving baseband symbols, adopting the fixed sampling rate to sample the baseband symbols, obtaining the baseband symbols, and adopting a B-spline fitting method to recover the baseband symbols on the position of a sampling point of a symbol clock for the obtained baseband symbols. The device comprises a receiver module which is used to receive the baseband symbols, a fixed adopting module, which is used to adopt the fixed sampling rate to obtain the baseband symbols and a re-sampling module which is used to adopt the B-spline fitting method to recover the baseband symbols on the position of the sampling point of the symbol clock for the obtained baseband symbols. The B-spline fitting method is not sensitive to frequency deviation of the carrier frequency since the B-spline fitting method is based on fitting calculation, and since noises damages to the sampling baseband symbols do not directly affect fitting of the B-spline, thereby the invention increases the ability of anti-frequency deviation and anti-interference, and the baseband symbols which are same with the sending end canbe recovered more accurate .

Description

technical field [0001] The invention relates to the technology of transmitting data in the field of communication, in particular to a method and device for clock recovery of an all-digital receiver. Background technique [0002] In a digital communication system, in order to ensure the correct transmission of data, the synchronization between digital communication devices must be guaranteed. The synchronization between digital communication devices includes the synchronization of carrier frequency recovery and clock recovery. [0003] At present, in order to accurately recover the baseband symbols, the digital communication receiver needs to have a clock that is consistent with the frequency of the baseband symbols sent by the transmitting end that sends the baseband symbols, so that the received baseband symbols can be sampled according to the recovered clock. Get the carried baseband signal. When the digital communication receiver adopts a phase-locked loop receiver, the ...

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Problems solved by technology

[0005] The Gardner clock recovery method based on Lagrange is a method using polynomial interpolation, which uses Lagrange polynomials as interpolation polynomials. The advantage is that the calculation is simple and the Farrow structure can be used. The disadvantage is the transition of low-order interpolation filters The bandwidth is relatively wide, the approximation speed is relatively slow, and the calculation of high-order interpolation is too complicated, which makes the commonly used low-order interpolation frequency characteristics not good; the second disadvantage is that Lagrange interpolation will appear when using high-order interpolation. Runge phenomenon The third disadvantage is that when Lagrange interpolation uses n times of interpolation, the error between the interpolated result and the interpolated function will not tend to 0 as n increases

[0018] The method of B-spline interpolation is widely used in digital communication system clock recovery and resampling technology, but, because the synchronization in the digital communication system receiver also includes carrier frequency synchronization, it is generally accurate to estimate and offset the carrier frequency deviation The impact is all after the clock recovery, which means that the clock recovery needs to work under the condition of a certain frequency offset, which puts forward higher requirements on the performance of the anti-frequency offset in the resampling process; The interference signal may directly destroy the sampled signal, and interpolation on the sampled baseband signal will cause error diffusion

[0019] In addition, the currently commonly used Gardner's TED method is derived from QPSK, which cannot be directly applied to general digital modulation methods such as QAM

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