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Frequency domain carrier frequency deviation rectifying method

A carrier frequency and frequency domain technology, applied in the field of carrier frequency deviation correction in the frequency domain, can solve problems such as high data volume and calculation requirements, large amounts of data, and rare reports on frequency deviation correction methods, so as to overcome the shortcomings of requiring a large amount of data and improve Timeliness effect

Active Publication Date: 2015-02-25
WUHAN POST & TELECOMM RES INST CO LTD
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Problems solved by technology

The method of frequency domain analysis to extract the frequency difference is to analyze the frequency domain of a large number of signals and then estimate the frequency difference. Tens of thousands of received symbols are used for FFT operation, so using this method to correct the carrier frequency often requires a large amount of data
At present, high-order modulation formats are used in high-speed digital optical communications to improve communication capacity, but frequency correction methods based on high-order modulation formats are rarely reported

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  • Frequency domain carrier frequency deviation rectifying method

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Embodiment Construction

[0016] The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

[0017] Such as figure 1 As shown, taking the QAM (Quadrature Amplitude Modulation, Quadrature Amplitude Modulation) format as an example, the frequency domain carrier frequency correction method of the present invention is described in detail:

[0018] A101. All the signals in the received signal set S0 are interconnected in pairs to form the first vector set S1; assuming that there are N received symbols in the received signal set S0, any symbol S0 i and S0 j For interconnection, the vector r obtained by pairwise interconnection ij The number is N*(N-1).

[0019] At the same time, all signals in the received signal S0 are frequency shifted by f 1 Afterwards, they are interconnected in pairs according to the above method to form the second vector set S2; wherein, all signal frequencies are offset by f 1 The practical approach is to multip...

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Abstract

The invention provides a frequency domain carrier frequency deviation rectifying method, which relates to the field of modulation-demodulation technologies and comprises the following steps that A101, all signals in a received signal set are pairwise interconnected to form a first vector set, and after frequencies of all the signals in the received signal set are deviated for a distance f1, the signals are pairwise interconnected to form a second vector set; A102, amplitude angles of the two vector sets are respectively calculated, and pi / 2 is subjected to a modular operation and is aligned into an interval (minus pi / 4, pi / 4), so as to obtain a first angle set and a second angle set; A103, angles in the two angle sets are subjected to an FFT (fast Fourier transform) operation, so as to find out a first frequency difference and a second frequency difference corresponding to respective peaks of the two angle sets; A104, if the first frequency difference is smaller than the second frequency difference, the first frequency difference is taken as the actual frequency deviation, and otherwise the negative value of the first frequency difference is taken as the actual frequency deviation; and A105, the signals in the signal sets are multiplied by corresponding frequency deviations delta f, and then deviation rectification is completed. The frequency domain carrier frequency deviation rectifying method has the advantages that the defect that mass of data is required in a frequency-domain analysis method is overcome, and frequency synchronization is completed on the basis of the limited data.

Description

technical field [0001] The invention relates to the technical field of modulation and demodulation, in particular to a carrier frequency correction method in the frequency domain. Background technique [0002] The synchronization of carrier frequency is an important link in coherent communication. Its purpose is to synchronize the frequency difference between the signal and the local oscillator frequency, and finally recover the phase information of the received signal accurately. In the field of optical communication, frequency compensation is mostly performed by digital processing methods, that is, various deviations are estimated and compensated by digital processing at the receiving end, instead of adjusting the wavelength of the light source. [0003] The digital frequency synchronization method is mostly based on the phase difference method or frequency domain analysis to extract the frequency difference: the phase difference method uses the phase difference of adjacen...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L25/02H04L25/03
Inventor 刘武杨超杨奇罗鸣
Owner WUHAN POST & TELECOMM RES INST CO LTD
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