CN109379310B - Rife-Quinn synthesis-based MPSK signal carrier frequency estimation method - Google Patents

Abstract

The invention discloses a MPSK signal carrier frequency estimation method based on Rife-Quinn synthesis, comprising the following steps: S10, acquiring a sample data sequence of the MPSK signal to be processed; S20, performing multiple square transformations on the MPSK signal and removing its direct current component, convert the MPSK signal carrier frequency estimation problem into the CW signal frequency estimation problem; S30, use the Rife interpolation algorithm to estimate the frequency of the CW signal, when the estimated signal spectrum leakage becomes larger, use the Quinn interpolation algorithm to correct the direction of Rife interpolation ; S40, calculate the carrier frequency of the MPSK signal according to the frequency estimation value of the CW signal. Compared with the traditional Rife interpolation and Quinn interpolation, the method of the present invention can accurately estimate the carrier frequency of the MPSK signal in the environment of low signal data volume and low signal-to-noise ratio, and is suitable for fast and robust estimation of the carrier frequency of the MPSK signal in engineering. .

Description

Rife-Quinn synthesis-based MPSK signal carrier frequency estimation method

Technical Field

The invention belongs to the field of signal processing, and particularly relates to a Rife-Quinn synthesis-based MPSK signal carrier frequency estimation method.

Background

Due to good anti-noise performance, MPSK (multiple Phase Shift keying) signals are widely used in the field of aerial and underwater communication, so that the signals have important military significance for detecting and parameter estimation of uncooperative MPSK signals, accurate estimation of MPSK signal carrier frequency is a premise that many other signal parameters can be estimated, and currently, common MPSK signal carrier frequency estimation methods mainly include wavelet transformation methods, spectrum correlation methods, square transformation methods and the like.

The carrier frequency estimation method based on wavelet transformation can simultaneously estimate the carrier frequency and the code rate of signals under the condition of lower signal-to-noise ratio, but the performance difference of the carrier frequency is obviously estimated under different wavelet functions and scale factors by the method based on wavelet transformation, and no solution is found for how to select the optimal wavelet basis function and scale factor. The carrier frequency estimation method based on the spectrum correlation can simultaneously estimate the carrier frequency and the code rate of a signal under the condition of low signal-to-noise ratio and has stronger anti-jamming capability, but the method can only directly estimate the carrier frequency of a BPSK signal, other MPSK signal carrier frequencies can be used for carrier frequency estimation after nonlinear transformation, in addition, the complexity of an algorithm for calculating a signal spectrum correlation function is higher, a spectrum peak search needs to be carried out on a two-dimensional plane of the spectrum correlation function when the signal carrier frequency is estimated, and the operation amount of the algorithm is further increased, so that the algorithm is difficult to be used in engineering practice. The method based on square transformation generally converts an MPSK signal into a CW signal by using square transformation, and then performs carrier frequency estimation through a Rife interpolation or Quinn interpolation algorithm, which has low algorithm complexity, but the interpolation direction of the Rife interpolation or the Quinn interpolation may be wrong under the conditions of low signal-to-noise ratio and low data volume, so that the carrier frequency estimation precision is reduced, and how to reduce the error probability of the interpolation direction to improve the carrier frequency estimation precision is a problem to be solved urgently at present.

Disclosure of Invention

The purpose of the invention is as follows: aiming at the defects of the prior art, the invention provides the MPSK signal carrier frequency estimation method which is small in calculation complexity and high in estimation accuracy under the environment with low signal-to-noise ratio and low signal data volume.

The technical scheme is as follows: in order to achieve the purpose, the invention adopts the following technical scheme:

a carrier frequency estimation method of MPSK signals based on Rife-Quinn synthesis comprises the following steps:

s10, acquiring MPSK signal sampling data sequence to be processed, wherein the signal sampling frequency is f_s；

S20, converting the MPSK signal carrier frequency estimation problem into a CW signal frequency estimation problem by carrying out multiple square transformation on the MPSK signal and removing the direct current component of the MPSK signal;

s30, carrying out frequency estimation on the CW signal by using a Rife interpolation algorithm, and correcting the Rife interpolation direction by using a Quinn interpolation algorithm when the frequency spectrum leakage of the estimated signal is large;

and S40, calculating the MPSK signal carrier frequency according to the frequency estimation value of the CW signal.

Preferably, in step S10, the real-time collected data of N sampling points is received from the sensor, or the data of N sampling points starting from the time when the signal is detected is extracted from the memory as the MPSK signal data sequence x (N) to be processed, where N is 0,1, …, N-1.

Preferably, the step S20 includes the steps of:

s21, squaring the signal to obtain a signal x after the signal is squared₂(n) is:

x₂(n)＝x²(n),n＝0,1,2,…N-1 (1)

s22, squaring signal x₂(n) Fourier transform to obtain its frequency spectrum X₂(f) Namely:

X₂(f)＝FFT{x₂(n)} (2)

wherein f is-f_s/2,-f_s/2+f_s/N,…f_s/2-f_sthe/N, FFT {. is } represents the calculation of Fourier transform; and make X₂(0) 0, thereby removing the direct current component in the frequency spectrum; then for X at this time₂(f) Performing inverse Fourier transform to obtain x₂(n) time domain signal x 'after removal of DC component'₂(n) is:

x'₂(n)＝IFFT{X₂(f)} (3)

wherein IFFT {. denotes inverse Fourier transform;

when the MPSK signal is a BPSK signal, only one square transformation is needed to remove direct current operation, and x 'at the moment'₂(n) is a CW signal containing no DC component; for 4PSK signals, two square conversion DC removing operations are needed, namely, time domain signal x'₂(n) the operations in steps S21, S22 are performed again, and so on for other MPSK-like signals.

Preferably, the step S30 includes the steps of:

s31 for x 'obtained in step S20'₂(n) Fourier transform and taking its frequency spectrum X'₂(f) The positive half-frequency part of (a), namely:

X'₂(f)＝FFT{x'₂(n)},f＞0 (4)

and look for | X'₂(f) Maximum frequency at the peak of the spectrumPoint number index k of point correspondences₀Where | · | represents a modulo operation, and:

k₀＝max(k) (5)

wherein k represents | X'₂(f) The discrete point index corresponding to the discrete frequency point corresponding to each spectrum peak, the value range of k is more than or equal to 1 and less than or equal to N/2-1, and max {. cndot } represents the operation of solving the maximum value;

s32, estimating x 'by Rife interpolation'₂Frequency of (n)

The calculation formula of the Rife interpolation is as follows:

when | X'₂(k₀+1)|＞|X′₂(k₀-1) | is α ═ 1; when | X'₂(k₀+1)|≤|X′₂(k₀-1) |, α ═ 1, α denotes the interpolation direction of the Rife interpolation algorithm; simultaneously determining the ratio r₀：

r₀Represents a frequency spectrum X'₂(k) At k₀The degree of leakage of (c);

s33, p 'x'₂(n) the signal is cut off to obtain the cut-off data x ″₂(n) the length of truncation W is:

namely:

x″₂(n)＝x'₂(n),n＝0,1,2,…W-1 (9)

wherein round {. } represents a rounding operation, and for x'₂' (n) Fourier transform to obtain its amplitudeThe power spectrum is taken and the positive frequency part is marked as X ″₂(f₁) Namely:

X″₂(f₁)＝|FFT{x″₂(n)}|,f₁＞0 (10)

where f is₁＝-f_s/2,-f_s/2+f_s/W,…f_s/2-f_sW, then look for X ″)₂(f₁) Discrete point index k 'corresponding to maximum discrete frequency point corresponding to spectral peak'₀Namely:

k'₀＝max(k') (11)

wherein k' represents X ″)₂(f₁) The discrete point index corresponding to the corresponding discrete frequency point at each spectral peak, the value range of k 'is more than or equal to 1 and less than or equal to k'. ltoreq.W/2-1, and the ratio r is solved₁：

r₁Denotes the frequency spectrum X ″₂(k ') is k'₀The degree of leakage of (c);

s34, comparison r₀And r₁If r is₁≥r₀X'₂(n) is the final frequency estimate

If r₁＜r₀Then, the direction of the Rife interpolation algorithm is judged again by using the Quinn interpolation algorithm, and the specific process is as follows:

according to the Quinn interpolation algorithm, solving a frequency correction term delta in the Quinn interpolation algorithm, and then combining the step S32 to judge that:

if in step S32 | X'₂(k₀+1)|＞|X′₂(k₀-1) | and δ > 0, the interpolation direction of the Rife is considered correct, and no correction is needed to the interpolation direction, if | X'₂(k₀+1)|＞|X′₂(k₀-1) | and δ < 0, when the direction of the Rife interpolation is considered to be wrong, and let α ═ α, useFormula (6) is newly paired with x'₂(n) estimating the frequency;

similarly, if | X 'in step S32'₂(k₀+1)|＜|X′₂(k₀-1) | and δ < 0, the direction of Rife interpolation is considered correct, and no correction is needed to the interpolation direction, if | X'₂(k₀+1)|＜|X′₂(k₀-1) | and δ > 0, at which point the direction of the Rife interpolation is considered as wrong, let α ═ α, and re-pair x 'using equation (6)'₂The frequency of (n) is estimated.

Preferably, the step S40 includes the steps of:

according to the step S30, the frequency estimated after the Rife interpolation algorithm is corrected through the Quinn interpolation algorithm

Carrier frequency F of MPSK signal_cThe calculation formula is as follows:

where M is 2 when x (n) is a BPSK signal, M is 4psk (qpsk), and M is 4 when x (n) is a BPSK signal, and so on.

Has the advantages that: the invention converts the MPSK signal into the CW signal by the square transformation DC-removing method, and estimates the carrier frequency of the MPSK signal by carrying out the Rife-Quinn comprehensive frequency estimation method on the CW signal. The method greatly improves the carrier frequency estimation precision of the CW signal under the environment with low signal-to-noise ratio and low signal data quantity by integrating the Rife interpolation algorithm and the Quinn interpolation algorithm, further improves the carrier frequency estimation precision of the MPSK signal, has small calculated amount, and is suitable for quickly and stably estimating the MPSK signal carrier frequency in engineering.

Drawings

FIG. 1 is a flow chart of a method of the present invention;

fig. 2 is a time domain diagram of a BPSK signal according to an embodiment of the present invention;

fig. 3 is a BPSK signal power spectrum according to an embodiment of the present invention;

fig. 4 is a magnitude spectrogram of a BPSK signal after dc removal by square according to an embodiment of the present invention;

fig. 5 is a graph comparing the performance of the method of the present invention and the prior art method on carrier frequency estimation of BPSK signal.

Detailed Description

The technical scheme of the invention is further explained by combining the attached drawings.

As shown in fig. 1, the method for estimating carrier frequency of MPSK signal based on Rife-Quinn synthesis of the present invention includes the following steps:

and S10, acquiring the MPSK signal sampling data sequence to be processed.

Receiving real-time acquisition data of N sampling points from a sensor as an MPSK signal data sequence x (N) to be processed, wherein N is 0,1, … and N-1, or extracting data of N sampling points starting from the moment of detecting the signal from a memory as the MPSK signal data sequence x (N) to be processed, N is 0,1, … and N-1, and the sampling frequency of the signal is recorded as f_s。

S20, converting the MPSK signal carrier frequency estimation problem into the CW signal frequency estimation problem by performing multiple square transform on the MPSK signal and removing the dc component thereof.

The method specifically comprises the following steps:

s21, squaring the signal to obtain a signal x after the signal is squared₂(n) that is

x₂(n)＝x²(n),n＝0,1,2,…N-1 (1)

S22, then squaring the signal x₂(n) Fourier transform to obtain its frequency spectrum X₂(f) Namely:

X₂(f)＝FFT{x₂(n)} (2)

wherein f denotes the signal frequency, f-f_s/2,-f_s/2+f_s/N,…f_s/2-f_sthe/N, FFT {. cndot } represents the Fourier transform operation. And make X₂(0) 0, thereby removing the dc component in the spectrum. Then, for X at this time₂(f) Performing inverse Fourier transform to obtain x₂(n) removing DC componentPost-quantization time-domain signal x'₂(n) is:

x'₂(n)＝IFFT{X₂(f)} (3)

where IFFT { · } represents an inverse fourier transform.

When the MPSK signal is a BPSK signal, only one square transformation is needed to remove direct current operation, and x 'at the moment'₂The CW signal (sinusoidal signal) containing no dc component is (n). For 4PSK signals, two square conversion DC removing operations are needed, namely, time domain signal x'₂(n) performing the operations in steps S21, S22 again; three times of square transformation de-direct current operation is needed for 8PSK signals, namely steps S21-S22 need to be performed three times. Other MPSK like signals and so on.

S30, processing the obtained signal x 'in S20 by adopting a Rife-Quinn comprehensive algorithm'₂(n) performing frequency estimation.

The Rife-Quinn comprehensive algorithm in the invention means that a Rife interpolation algorithm is used for carrying out frequency estimation on a CW signal, and when the frequency spectrum leakage of the estimated signal becomes large, the Quinn interpolation algorithm is used for correcting the Rife interpolation direction. The method specifically comprises the following steps:

s31, first comparing the x 'obtained in the step S20'₂(n) Fourier transform and taking its frequency spectrum X'₂(f) The positive half-frequency part of (a), namely:

X'₂(f)＝FFT{x'₂(n)},f＞0 (4)

and look for | X'₂(f) The point index k corresponding to the maximum frequency point corresponding to the peak of the | spectrum (the frequency corresponding to the frequency point is the frequency of the CW signal)₀Where | · | represents a modulo operation, and:

k₀＝max(k) (5)

wherein k represents | X'₂(f) And | discrete point index corresponding to the corresponding discrete frequency point at each spectral peak, k is within the range of 1 to N/2-1, and max {. can } represents the operation of solving the maximum value.

S32, followed by estimating x 'using Rife interpolation'₂Frequency of (n)

The calculation formula of the Rife interpolation is as follows:

when | X'₂(k₀+1)|＞|X′₂(k₀-1) | is α ═ 1; when | X'₂(k₀+1)|≤|X′₂(k₀-1) |, α ═ 1, α denotes the interpolation direction of the Rife interpolation algorithm. Simultaneously determining the ratio r₀：

According to the Fourier transform theory, r₀Can reflect the frequency spectrum X'₂(k) At k₀Degree of leakage of (d)₀The larger the size, the smaller the degree of spectral leakage, and vice versa₀Smaller indicates greater spectral leakage.

S33, then p'₂(n) the signal is cut off to obtain the cut-off data x ″₂(n) the length of truncation W is:

namely:

x″₂(n)＝x'₂(n),n＝0,1,2,…W-1 (9)

where round {. cndot } represents a rounding operation and is on x ″ "₂(n) Fourier transform is carried out to obtain a magnitude spectrum of the frequency spectrum and the positive frequency part of the magnitude spectrum is marked as X ″₂(f₁) Namely:

X″₂(f₁)＝|FFT{x″₂(n)}|,f₁＞0 (10)

where f is₁＝-f_s/2,-f_s/2+f_s/W,…f_s/2-f_s/W，Then look for X ″)₂(f₁) Discrete point index k 'corresponding to maximum discrete frequency point corresponding to spectral peak'₀Namely:

k'₀＝max(k') (11)

wherein k' represents X ″)₂(f₁) The discrete point index corresponding to the corresponding discrete frequency point at each spectral peak, the value range of k 'is more than or equal to 1 and less than or equal to k'. ltoreq.W/2-1, and the ratio r is solved₁：

For the same reason r₁Can reflect the frequency spectrum X ″)₂(k ') is k'₀The degree of leakage of (c).

S34, comparing the leakage degree at the spectral peak before and after Rife interpolation estimation, if r₁≥r₀X'₂(n) is the final frequency estimate

If r₁＜r₀If so, it is indicated that the direction of the Rife interpolation in the formula (6) may be wrong, and at this time, the Quinn interpolation algorithm is used to re-determine the direction of the Rife interpolation algorithm, and the specific process is as follows:

firstly, according to a Quinn interpolation algorithm, solving a frequency correction term delta in the Quinn interpolation algorithm, wherein a calculation formula of the delta is as follows:

wherein:

wherein:

wherein: re {. is used for representing the real part operation of the data. Then if in step S32, | X'₂(k₀+1)|＞|X′₂(k₀-1) | and δ > 0, the interpolation direction of the Rife is considered correct, and no correction is needed to the interpolation direction, if | X'₂(k₀+1)|＞|X′₂(k₀-1) | and δ < 0, in which case the direction of the Rife interpolation is considered to be wrong, α ═ α, and x 'is newly corrected using equation (6)'₂The frequency of (n) is estimated. Similarly, if in step S32, | X'₂(k₀+1)|＜|X′₂(k₀-1) | and δ < 0, the direction of Rife interpolation is considered correct, and no correction is needed to the interpolation direction, if | X'₂(k₀+1)|＜|X′₂(k₀-1) | and δ > 0, at which point the direction of the Rife interpolation is considered as wrong, let α ═ α, and re-pair x 'using equation (6)'₂The frequency of (n) is estimated.

In the steps S20 and S30, the fourier transform is a fast fourier transform, which improves the computation efficiency.

S40, according to the frequency estimated after the Rife interpolation algorithm is corrected through the Quinn interpolation algorithm in the step S30

Calculating MPSK signal carrier frequency F_cThe calculation formula is as follows:

where M is 2 when x (n) is a BPSK signal, M is 4 when x (n) is 4PSK (qpsk), M is 8 when x (n) is 8PSK, and so on.

According to the above-detailed MPSK signal carrier frequency estimation method based on Rife-Quinn synthesis, the effect of the invention is verified by a simulation experiment. In this embodiment, the mathematical model of the MPSK signal is:

x(t)＝s(t)+v(t)＝Acos(2πf_ct+θ_k)+v(t) (17)

where t represents time in seconds, A represents signal amplitude and is constant, v (t) is noise not related to signal s (t), f_cRepresenting the carrier frequency of the signal, theta_kA set of uniformly spaced modulated phases whose values depend on the values of the baseband symbols, so it can be written as:

m is a baseband symbol number, M is usually a power of 2, and x (t) is a BPSK signal when M is 2. In this embodiment, M is 2, that is, the BPSK signal is verified by simulation.

The simulation signal parameters are set as follows: sampling frequency f_s10000Hz, carrier frequency f of BPSK signal_c1276.85Hz, the code rate is 1000bit/s, and the noise is white Gaussian noise.

Figure 2 is a time domain diagram of a BPSK signal; fig. 3 is a power spectrum of a BPSK signal; fig. 4 shows a fourier-transformed amplitude spectrum of a CW signal, which is a signal obtained by removing dc by BPSK square transformation. Fig. 5 shows the comparison between the performance of the carrier frequency of BPSK signal estimated by the method of the present invention and the performance of the Rife interpolation and the Quinn interpolation estimation and the CRLB (cramer-mello boundary, a lower limit of the parameter estimation performance), where the data length is 0.423s and the number of monte carlo trials is 1000, and it can be seen from the figure that the performance of the method of the present invention is better than that of the conventional Rife interpolation and the Quinn interpolation in the low signal-to-noise ratio and low signal data volume environments, and the frequency performance estimated by the method is closer to the CRLB in the low signal-to-noise ratio environments.

The result of the embodiment shows that the error between the signal carrier frequency estimated by the MPSK signal carrier frequency estimation method and the real carrier frequency is very small in the low signal-to-noise ratio environment, and the method is suitable for the occasion of quickly and accurately estimating the MPSK signal carrier frequency.

Claims (4)

1. A carrier frequency estimation method of MPSK signals based on Rife-Quinn synthesis is characterized by comprising the following steps:

s10, acquiring MPSK signal sample data sequence to be processedNumber sampling frequency of f_s；

S20, converting the MPSK signal carrier frequency estimation problem into the CW signal frequency estimation problem by performing multiple square transform on the MPSK signal and removing the dc component thereof, including:

s21, squaring the signal to obtain a signal x after the signal is squared₂(n) is:

x₂(n)＝x²(n),n＝0,1,2,…N-1 (1)

s22, squaring signal x₂(n) Fourier transform to obtain its frequency spectrum X₂(f) Namely:

X₂(f)＝FFT{x₂(n)} (2)

wherein f is-f_s/2,-f_s/2+f_s/N,…f_s/2-f_sthe/N, FFT {. is } represents the calculation of Fourier transform; and make X₂(0) 0, thereby removing the direct current component in the frequency spectrum; then for X at this time₂(f) Performing inverse Fourier transform to obtain x₂(n) time domain signal x 'after removal of DC component'₂(n) is:

x'₂(n)＝IFFT{X₂(f)} (3)

wherein IFFT {. denotes inverse Fourier transform;

when the MPSK signal is a BPSK signal, only one square transformation is needed to remove direct current operation, and x 'at the moment'₂(n) is a CW signal containing no DC component; for 4PSK signals, two square conversion DC removing operations are needed, namely, time domain signal x'₂(n) performing the operations in steps S21, S22 again, and so on for other MPSK-like signals;

s30, performing frequency estimation on the CW signal by using a Rife interpolation algorithm, and correcting the Rife interpolation direction by using a Quinn interpolation algorithm when the estimated signal spectrum leakage becomes large, the method includes:

s31 for x 'obtained in step S20'₂(n) Fourier transform and taking its frequency spectrum X'₂(f) The positive half-frequency part of (a), namely:

X'₂(f)＝FFT{x'₂(n)},f＞0 (4)

and searching a point index k corresponding to the maximum frequency point corresponding to the spectrum peak of the | X' 2(f) |₀Where | · | represents a modulo operation, and:

k₀＝max(k) (5)

wherein k represents | X'₂(f) The discrete point index corresponding to the discrete frequency point corresponding to each spectrum peak, the value range of k is more than or equal to 1 and less than or equal to N/2-1, and max {. cndot } represents the operation of solving the maximum value;

s32, estimating x 'by Rife interpolation'₂Frequency of (n)

The calculation formula of the Rife interpolation is as follows:

when | X'₂(k₀+1)|＞|X′₂(k₀-1) | is α ═ 1; when | X'₂(k₀+1)|≤|X′₂(k₀-1) |, α ═ 1, α denotes the interpolation direction of the Rife interpolation algorithm; simultaneously determining the ratio r₀：

r₀Represents a frequency spectrum X'₂(k) At k₀The degree of leakage of (c);

s33, p 'x'₂(n) the signal is cut off to obtain the cut-off data x ″₂(n) the length of truncation W is:

namely:

x″₂(n)＝x'₂(n),n＝0,1,2,…W-1 (9)

where round {. cndot } represents a rounding operation and is on x ″ "₂(n) Fourier transform is carried out to obtain a magnitude spectrum of the frequency spectrum and the positive frequency part of the magnitude spectrum is marked as X ″₂(f₁) Namely:

X″₂(f₁)＝|FFT{x″₂(n)}|,f₁＞0 (10)

where f is₁＝-f_s/2,-f_s/2+f_s/W,…f_s/2-f_sW, then look for X ″)₂(f₁) Discrete point index k 'corresponding to maximum discrete frequency point corresponding to spectral peak'₀Namely:

k'₀＝max(k') (11)

wherein k' represents X ″)₂(f₁) The discrete point index corresponding to the corresponding discrete frequency point at each spectral peak, the value range of k 'is more than or equal to 1 and less than or equal to k'. ltoreq.W/2-1, and the ratio r is solved₁：

r₁Denotes the frequency spectrum X ″₂(k ') is k'₀The degree of leakage of (c);

s34, comparison r₀And r₁If r is₁≥r₀X'₂(n) is the final frequency estimate

If r₁＜r₀Then, the direction of the Rife interpolation algorithm is judged again by using the Quinn interpolation algorithm, and the specific process is as follows:

according to the Quinn interpolation algorithm, solving a frequency correction term delta in the Quinn interpolation algorithm, and then combining the step S32 to judge that:

if in step S32 | X'₂(k₀+1)|＞|X′₂(k₀-1) | and δ > 0, when the direction of the Rife interpolation is considered correct, without having to do soCorrecting the interpolation direction to obtain a value of | X'₂(k₀+1)|＞|X′₂(k₀-1) | and δ < 0, in which case the direction of the Rife interpolation is considered to be wrong, α ═ α, and x 'is newly corrected using equation (6)'₂(n) estimating the frequency;

similarly, if | X 'in step S32'₂(k₀+1)|＜|X′₂(k₀-1) | and δ < 0, the direction of Rife interpolation is considered correct, and no correction is needed to the interpolation direction, if | X'₂(k₀+1)|＜|X′₂(k₀-1) | and δ > 0, at which point the direction of the Rife interpolation is considered as wrong, let α ═ α, and re-pair x 'using equation (6)'₂(n) estimating the frequency;

and S40, calculating the MPSK signal carrier frequency according to the frequency estimation value of the CW signal.

2. The method for estimating carrier frequency of MPSK signal based on Rife-Quinn synthesis as claimed in claim 1, wherein in step S10, the real-time collected data of N sampling points is received from the sensor, or the data of N sampling points starting from the moment of detecting the signal is extracted from the memory as the MPSK signal data sequence x (N) to be processed, where N is 0,1, …, N-1.

3. The method for estimating carrier frequency of MPSK signal based on Rife-Quinn synthesis as claimed in claim 1, wherein the step S40 comprises the following steps:

according to the step S30, the frequency estimated after the Rife interpolation algorithm is corrected through the Quinn interpolation algorithm

Carrier frequency F of MPSK signal_cThe calculation formula is as follows:

where M is 2 when x (n) is a BPSK signal, M is 4psk (qpsk), and M is 4 when x (n) is a BPSK signal, and so on.

4. The method for carrier frequency estimation of MPSK signals based on Rife-Quinn synthesis as claimed in claim 1, wherein the Fourier transform is fast Fourier transform.

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