Time-frequency difference parameter estimation method based on differential correlation method

Abstract

The invention discloses a time-frequency difference parameter estimation method based on a differential correlation method, and relates to the technical field of communication. The method is used for carrying out time difference and frequency difference parameter estimation on interference target transmitting signals received by two receiving stations respectively, and comprises the following steps: firstly, carrying out delay, conjugate point multiplication and Fourier transform on the interference target transmitting signals received by the two receiving stations respectively; performing conjugate point multiplication and Fourier transform, transforming to a time domain, calculating a position corresponding to a maximum value, and recording the position as a time difference parameter; performing conjugate point multiplication and Fourier transform on the signal subjected to time difference compensation, calculating a position corresponding to a maximum value of a result, and recording the position as a frequency difference parameter; according to the method, the time-frequency difference parameter estimation is carried out by introducing the difference correlation method, so that the real-time performance of the time-frequency difference parameter estimation is improved.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a time-frequency difference parameter estimation method based on a differential correlation method. Background Art

[0002] For a positioning system based on time difference and frequency difference, the estimation of its time difference and frequency difference parameters is the key to the positioning effect. There are many traditional methods for estimating time-frequency difference parameters, such as short-time Fourier transform (STFT), Wigner-Wiley distribution (WV), Gabor expansion, wavelet transform, etc., which mainly realize the signal analysis function by constructing different time-frequency kernel functions. To estimate the time-frequency difference parameters, a large amount of calculation is required, which can only be achieved in real time through GPU acceleration. CPU cannot achieve real-time parameter estimation. Summary of the invention

[0003] In view of this, the present invention proposes a time-frequency difference parameter estimation method based on the differential correlation method. The method introduces the differential correlation method to perform time-frequency difference parameter estimation, thereby improving the real-time performance of the time-frequency difference parameter estimation.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] A time-frequency difference parameter estimation method based on a differential correlation method is used to estimate the time difference and frequency difference parameters of interference target transmission signals respectively received by two receiving stations, and specifically comprises the following steps:

[0006] Step 1: record the interference target transmission signals received by the two receiving stations as x(t) and y(t), respectively, and record y(t) as:

[0007]

[0008] D t represents the time difference parameter between y(t) and x(t), D f represents the frequency difference parameter between y(t) and x(t), j represents the imaginary unit, D t With D f All are unknown;

[0009] Step 2, delay x(t) by τ0 to obtain x(t-τ0), 0<τ0<T, then perform conjugate dot multiplication with the original signal and perform Fourier transform:

[0010] F x (w) = F(x(t)·x * (t-τ0));

[0011] Where F(·) represents Fourier transform, T represents the total duration of the signal used to estimate the time-frequency difference, and the superscript * represents conjugation;

[0012] Step 3, delay y(t) by τ0 to obtain y(t-τ0), then perform conjugate dot multiplication with the original signal and perform Fourier transform:

[0013] F y (w) = F(y(t)·y * (t-τ0));

[0014] Step 4: Perform conjugate dot multiplication on the results of step 2 and step 3, and perform Fourier transform:

[0015] F xy (w) = F[x(t)·x * (t-τ0)]·F * [y(t)·y * (t-τ0)];

[0016] Step 5, transform the result obtained in step 4 into the time domain:

[0017] A(t) = IFFT(F[x(t)·x * (t-τ0)]·F * [y(t)·y * (t-τ0)]);

[0018] Where IFFT(·) represents inverse fast Fourier transform;

[0019] Step 6: Calculate the position corresponding to the maximum value of A(t) and record it as the time difference D between y(t) and x(t) t :

[0020]

[0021] Among them, -T <t<T;

[0022] Step 7: x(tD t ) is conjugate dot-multiplied with y(t) and Fourier transformed:

[0023] s(t)=x(tD t )·y * (t);

[0024] S(f) = F[s(t)];

[0025] Step 8: Calculate the position corresponding to the maximum value of S(f) and record it as the frequency difference D between y(t) and x(t) f :

[0026]

[0027] in, f s Indicates the signal sampling rate.

[0028] Due to the adoption of the above technical solution, the beneficial effects of the present invention compared with the prior art are:

[0029] The present invention introduces a differential correlation method to estimate the time-frequency difference parameters. Since the calculation amount of the differential correlation method is only related to the signal length, the signal length is fixed, and the calculation amount is determined, the real-time performance of the time-frequency difference parameter estimation is improved, and the analysis result has a higher use value. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The figure is an overall flow chart of a time-frequency difference parameter estimation method based on a differential correlation method in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0032] A time-frequency difference parameter estimation method based on differential correlation method is used to estimate the time difference and frequency difference parameters of interference target transmission signals received by two receiving stations respectively, such as Figure 1 As shown, the specific steps include:

[0033] Step 1: record the interference target transmission signals received by the two receiving stations as x(t) and y(t), respectively, and record y(t) as:

[0034]

[0035] D t represents the time difference parameter between y(t) and x(t), D f represents the frequency difference parameter between y(t) and x(t), j represents the imaginary unit, D t With D f are all unknown numbers; specifically, in this embodiment, y(t) is recorded as the primary satellite signal, and x(t) is recorded as the neighboring satellite signal;

[0036] Step 2, delay x(t) by τ0 to obtain x(t-τ0), 0<τ0<T, then perform conjugate dot multiplication with the original signal and perform Fourier transform:

[0037] F x (w) = F(x(t)·x * (t-τ0));

[0038] Where F(·) represents Fourier transform, T represents the total duration of the signal used to estimate the time-frequency difference, and the superscript * represents conjugation; specifically, τ0 is generally selected as 8 symbol durations;

[0039] Step 3, delay y(t) by τ0 to obtain y(t-τ0), then perform conjugate dot multiplication with the original signal and perform Fourier transform:

[0040] F y (w) = F(y(t)·y * (t-τ0));

[0041] Step 4: Perform conjugate dot multiplication on the results of step 2 and step 3, and perform Fourier transform:

[0042] F xy (w) = F[x(t)·x * (t-τ0)]·F * [y(t)·y * (t-τ0)];

[0043] Step 5, transform the result obtained in step 4 into the time domain:

[0044] A(t) = IFFT(F[x(t)·x * (t-τ0)]·F * [y(t)·y * (t-τ0)]);

[0045] Where IFFT(·) represents inverse fast Fourier transform;

[0046] Step 6: Calculate the position corresponding to the maximum value of A(t) and record it as the time difference D between y(t) and x(t) t :

[0047]

[0048] Among them, -T <t<T;

[0049] Step 7: x(tD t ) is conjugate dot-multiplied with y(t) and Fourier transformed:

[0050] s(t)=x(tD t )·y * (t);

[0051] S(f) = F[s(t)];

[0052] Step 8: Calculate the position corresponding to the maximum value of S(f) and record it as the frequency difference D between y(t) and x(t) f :

[0053]

[0054] in, fs Indicates the signal sampling rate.

[0055] In summary, the present invention introduces the differential correlation method to estimate the time-frequency difference parameters. The calculation amount of the differential correlation method is only related to the signal length. If the signal length is fixed, the calculation amount is determined, which has significant advantages over traditional methods.

[0056] Those skilled in the art will appreciate that the embodiments described are intended to help readers understand the principles of the present invention, and should be understood that the scope of protection of the present invention is not limited to the embodiments described. For those skilled in the art, the present invention may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A time-frequency difference parameter estimation method based on differential correlation method, used for estimating time difference and frequency difference parameters of interference target transmission signals received by two receiving stations respectively, characterized in that: The specific steps include: Step 1: record the interference target transmission signals received by the two receiving stations as x(t) and y(t), respectively, and record y(t) as: D t represents the time difference parameter between y(t) and x(t), D f represents the frequency difference parameter between y(t) and x(t), j represents the imaginary unit, D t With D f All are unknown; Step 2, delay x(t) by τ0 to obtain x(t-τ0), 0<τ0<T, then perform conjugate dot multiplication with the original signal and perform Fourier transform: F x (w)=F(x(t)·x * (t-τ0)); Where F(·) represents Fourier transform, T represents the total duration of the signal used to estimate the time-frequency difference, and the superscript * represents conjugation; Step 3, delay y(t) by τ0 to obtain y(t-τ0), then perform conjugate dot multiplication with the original signal and perform Fourier transform: F y (w)=F(y(t)·y * (t-τ0)); Step 4: Perform conjugate dot multiplication on the results of step 2 and step 3, and perform Fourier transform: F xy (w)=F[x(t)·x * (t-τ0)]·F * [y(t)·y * (t-τ0)]; Step 5, transform the result obtained in step 4 into the time domain: A(t)=IFFT(F[x(t)·x * (t-τ0)]·F * [y(t)·y * (t-τ0)]); Where IFFT(·) represents inverse fast Fourier transform; Step 6: Calculate the position corresponding to the maximum value of A(t) and record it as the time difference D between y(t) and x(t) t : Among them, -T <t<T; Step 7: x(tD t ) is conjugate dot-multiplied with y(t) and Fourier transformed: s(t)=x(t-D t )·y * (t); S(f) = F[s(t)]; Step 8: Calculate the position corresponding to the maximum value of S(f) and record it as the frequency difference D between y(t) and x(t) f : in, f s Indicates the signal sampling rate.

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