CN115684718A - Frequency estimation method - Google Patents

Abstract

The invention discloses a frequency estimation method, which comprises the following steps: 1) A radar echo simulator receives a radio frequency emission signal emitted by a radar; 2) Carrying out down-conversion treatment on the signal in the step 1); 3) Performing analog-to-digital conversion processing on the signals in the step 2); 4) Carrying out digital IQ decomposition processing on the signals in the step 3); 5) Performing FFT on the signals in the step 4); 6) Solving the frequency f1 and f2 of the peak value and the secondary peak value of the FFT according to the signal in the step 5); 7) Generating signals with frequencies from f1 to f2, and respectively carrying out correlation processing on the signals in the step 4); 8) And (3) the frequency of the signal maximum value in the step 7) is the estimated frequency. The digital frequency measurement technology is optimized and improved, the calculation times can be reduced, the calculation time is shortened, the purpose of rapidly measuring the frequency is achieved, and meanwhile, the cost of the system is reduced.

Description

Frequency estimation method

Technical Field

The invention relates to the technical field of digital frequency measurement, in particular to a frequency estimation method.

Background

Frequency estimation of signals is a classical and important signal processing problem, and has extremely wide application in the fields of science and engineering. In an electric power system, frequency is one of the most important power quality parameters, the change of the frequency reflects the dynamic balance between power generation and load, and the dynamic process monitoring of the system can be realized through the accurate estimation of the frequency and the change of the frequency. In addition, in specific applications such as measurement benchmark testing and standard tracing, the frequency estimation accuracy is often required to be higher, the existing frequency estimation method is generally calculated based on hardware, and in order to meet the frequency accuracy, the resource overhead is increased, and the purpose of measuring the frequency at low cost cannot be achieved.

Disclosure of Invention

The present invention is directed to a frequency estimation method to solve the above problems.

The technical problem solved by the invention can be realized by adopting the following technical scheme:

a method of frequency estimation comprising the steps of:

1) A radar echo simulator receives a radio frequency emission signal emitted by a radar;

2) Carrying out down-conversion treatment on the signals in the step 1);

3) Performing analog-to-digital conversion processing on the signals in the step 2);

4) Carrying out digital IQ decomposition processing on the signals in the step 3);

5) Performing FFT on the signal in the step 4);

6) Solving the frequency f1 and f2 of the peak value and the secondary peak value of the FFT of the signal in the step 5);

7) Generating signals with frequencies from f1 to f2, and respectively carrying out correlation processing on the signals in the step 4);

8) And (3) the frequency of the signal maximum value in the step 7) is the estimated frequency.

Due to the adoption of the technical scheme, the digital frequency measurement technology is optimized and improved, so that the calculation times can be reduced, the calculation time can be shortened, the aim of rapidly measuring the frequency can be fulfilled, and the cost of the system can be reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a system block diagram of one embodiment of the present invention.

FIG. 2 is a signal spectrum diagram of an embodiment of the present invention when the sampling frequency fs is 1GHz, the signal is 35MHz, and the number of FFT points is 1024 points.

Fig. 3 is a signal spectrum diagram of fig. 2 after amplification in the vicinity of the peak.

Fig. 4 is a signal spectrum diagram of fig. 2 after amplification in the vicinity of the secondary peak.

Fig. 5 is a schematic diagram of the correlation between the peak and sub-peak values of fig. 3 and 4 and the original signal after correlation processing.

Fig. 6 is a partially enlarged view of fig. 5.

FIG. 7 is a signal spectrum diagram of an embodiment of the present invention when the sampling frequency fs is 1GHz, the signal is 35MHz, and the number of FFT points is 65536 points.

Fig. 8 is a graph of the signal spectrum of fig. 7 after amplification near the peak.

Detailed Description

In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further explained below.

Referring to fig. 1, a frequency estimation method includes the steps of:

1) A radar echo simulator receives a radio frequency emission signal emitted by a radar;

2) Carrying out down-conversion treatment on the signals in the step 1);

3) Performing analog-to-digital conversion processing on the signals in the step 2);

4) Carrying out digital IQ decomposition processing on the signals in the step 3);

5) Performing FFT on the signals in the step 4);

6) Solving the frequency f1 and f2 of the peak value and the secondary peak value of the FFT of the signal in the step 5);

7) Generating signals with frequencies from f1 to f2, and respectively carrying out relevant processing on the signals in the step 4);

8) And (4) determining the frequency of the maximum value of the signal in the step 7) as the estimated frequency.

For a signal with unknown frequency, an FFT can be performed to find a peak value to determine the frequency, if the frequency of the signal is to be accurately estimated, the number of FFT points is required to be sufficient, because the frequency resolution of the FFT is F = fs/(N-1), fs is a sampling frequency, and N is the number of FFT points, when fs is constant, the larger the N is, the higher the frequency resolution is, the more accurate the frequency estimation is, but the larger the number of FFT points is, the larger the calculation frequency is, the higher the system overhead is, and thus, the frequency measurement in a short time cannot be achieved.

For example, when fs is 1GHz, a signal is 35mhz, and fft points are 1024 points, the spectrum of the signal is shown in fig. 2. The vicinity of the peak is enlarged as shown in fig. 3. It can be seen from fig. 3 that the frequency of the signal peak is 35.68MHz when the number of FFT points is 1024 points, but is different from the real frequency of 35MHz by 0.68 MHz.

The method provided by the invention is implemented as follows, for the above example, the known peak value is 35.68MHz, the frequency of the secondary peak value is 34.7MHz (as shown in fig. 4), signals with the frequency from 34.71MHz to 35.67MHz are generated, the interval is 0.01MHz, the signals are respectively correlated with the original signals, the frequency of the peak value after correlation processing is searched and is the estimated frequency, as shown in fig. 5, and the frequency is amplified and is shown in fig. 6. It can be seen that the estimated frequency for the embodiment of the present invention is 35MHz.

Of course, the number of FFT points may be changed according to actual conditions, for example, when fs is 1GHz, the signal is 35mhz, and the number of FFT points is 65536 points, the spectrum of the signal is as shown in fig. 7, and after the vicinity of the peak is amplified as shown in fig. 8, it can be seen from fig. 8 that the frequency of the peak of the signal is 35.01MHz when the number of FFT points is 65536 points, but the frequency is different from the real frequency of 35MHz by 0.01 MHz. Similarly, the estimated frequency of the embodiment of the present invention can be estimated to be 35MHz by the above method.

The digital frequency measurement technology is optimized and improved, the calculation times can be reduced, the calculation time is shortened, the purpose of rapidly measuring the frequency is achieved, and meanwhile, the cost of the system is reduced.

The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (1)

1. A method of frequency estimation, comprising the steps of:

1) A radar echo simulator receives a radio frequency emission signal emitted by a radar;

2) Carrying out down-conversion treatment on the signals in the step 1);

3) Performing analog-to-digital conversion processing on the signals in the step 2);

4) Carrying out digital IQ decomposition processing on the signals in the step 3);

5) Performing FFT on the signals in the step 4);

6) Solving the frequency f1 and f2 of the peak value and the secondary peak value of the FFT of the signal in the step 5);

7) Generating signals with frequencies from f1 to f2, and respectively carrying out correlation processing on the signals in the step 4);

8) And (3) the frequency of the signal maximum value in the step 7) is the estimated frequency.

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