A Frequency Estimation Method of MFSK Signal Based on Spectrum Accumulation and Matching
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A technology of signal frequency and spectrum, applied in the field of signal processing, can solve the problems that non-cooperative communication is difficult to realize and cannot be widely used, and achieve the effect of reducing the amount of calculation and parameter influence, accurate estimation, and accurate prior knowledge
Active Publication Date: 2020-12-18
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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However, this method is mainly aimed at the demodulation of MFSK signals, and the estimation of the frequency mainly depends on the frequency tracking signal, which is difficult to realize in non-cooperative communication and cannot be widely used
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Embodiment 1
[0029] The purpose of this embodiment is to estimate the center frequencies and frequency increments of different 4FSK signals under different SNR scenarios, and to verify that the inventive method can realize accurate 4FSK signal frequency information estimation. In the present embodiment, the length of the simulated signal is N=62500, the sampling rate is Fs=6250Hz, the symbols are randomly generated, the symbol rate is 125Baud, and the center frequency of the signal modulation is f 0 = 2000Hz, the data frequency difference Af = 300Hz, the in-band signal-to-noise ratio steps from -5dB to 10dB by 1. Invented way:
[0030] S1, the received signal is {y 1 ,y 2 ,...,y N}, divide the data into K=10 segments, each segment length L=6250, get
[0031]
[0032] S2, for each piece of data s i Do FFT transformation to get w i , i=1, 2, ..., 10;
[0033] S3, right {w i}, i=1, ..., the elements of the first half of K are accumulated according to the following formula to obtain...
Embodiment 2
[0048] The purpose of this embodiment is to estimate the center frequency and frequency increment of 2FSK and 8FSK signals under different SNR scenarios, and to verify the estimation performance of the inventive method. In the present embodiment, the length of the simulated signal is N=40000, the sampling rate is Fs=8000Hz, the symbols are randomly generated, the symbol rate is 160Baud, and the center frequency of the signal modulation is f 0=2000Hz, data frequency difference △f=300Hz, in-band signal-to-noise ratio from 0dB to 10dB in steps of 1. Do 100 trials in the same manner as in Example 1, and obtain the normalized root mean square estimation error as image 3 shown.
[0049] The results show that the method proposed in the present invention can accurately estimate the frequency information of the MFSK signal, especially when the signal-to-noise ratio is low. For 4FSK signal at 1dB, the normalized root mean square error of the frequency increment estimation is less tha...
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Abstract
The invention belongs to the technical field of signal processing, and relates to an MFSK signal frequency estimation method based on spectrum accumulation matching. The MFSK signal frequency estimation method based on spectrum accumulation matching includes the steps: segmenting non-cooperative receiving signal and performing fast Fourier transform (FFT), taking a modulus and obtaining spectrums;correspondingly adding elements of the first half of each segment to obtain the accumulated data; in the accumulated data, according to different intervals and starting points, continuously taking m(m is a modulation system) segments, obtaining a maximum value of the vector after adding the corresponding elements of the m segments, and taking the maximum value of the vector as the element of thecorresponding position of a matrix M; and finally, based on the position of the maximum value of the matrix M, solving the MFSK frequency modulation parameter. The MFSK signal frequency estimation method based on spectrum accumulation matching can effectively estimate the MFSK signal modulation frequency, and has the advantages of greatly reducing the calculation amount, low requirement for the length of the received data, and having good performance at a low signal to noise ratio as the time-frequency analysis is not needed, compared with an estimation methods based on wavelet transform andshort-time Fourier transform.
Description
technical field [0001] The invention belongs to the technical field of signal processing, and relates to an MFSK signal frequency estimation method based on frequency spectrum accumulation and matching. Background technique [0002] Multi-ary frequency shift keying (MFSK) has good anti-multipath delay characteristics, and has been widely used in short-wave, ultra-short-wave radio stations and underwater acoustic communication channels in recent years. Accurate blind estimation of modulation parameters for such signals is a necessary link for non-cooperative receivers to complete signal matching identification and blind demodulation, and it is also an important content in spectrum monitoring and communication countermeasures. At present, there have been a lot of researches on the problem of blind reception of MFSK signals, including signal modulation identification, symbol rate, symbol synchronization information, and signal demodulation based on these researches, but there a...
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