Instrument response removing method suitable for different parameter file formats

Abstract

The invention relates to an instrument response removing method suitable for different parameter file formats, which can be used for analyzing station parameter files in various formats and carrying out instrument response removing processing on waveform data. Firstly, instrument response parameter files are classified, and a corresponding key parameter extraction method and an instrument response removing method are designed according to different format characteristics, so that the method is suitable for instrument response removing processing of waveform data of different seismic stations. Corresponding algorithms are designed for different instrument response types, and automatic processing of instrument response of waveform data of different seismic stations is realized.

Description

Technical Field

[0001] The invention relates to the field of seismic data processing, and in particular to an instrument response removal method suitable for different parameter file formats. Background Art

[0002] One of the key steps in seismic data processing is to remove the instrument response of the original waveform data, thereby converting the digital record into an actual ground motion signal. The correctness of the instrument response removal method is directly related to the accuracy of subsequent amplitude measurement and magnitude calculation, so it is very important in seismic data preprocessing.

[0003] Removing instrument response requires the use of station meta-parameter files, i.e., instrument response files. With the development of seismic observation technology, the instrument response files of most seismic stations have gradually been converted to standard RESP and SACPZ formats. For these two formats, there are corresponding open source algorithms to read and parse them; however, for the International Seismic Monitoring Network (IMS), since the network includes both ordinary three-way stations and arrays composed of multiple substations, its instrument response files have many types, which can be roughly divided into paz format containing zero-pole information (specifically including paz, pazfir, firpaz, pazfap), par format, and fap format containing amplitude-frequency response information. Currently, there is no public algorithm to parse these formats.

[0004] In my country's earthquake monitoring network, there are stations from both the China Earthquake Networks Center and international open networks and international monitoring systems, which makes the types of station parameter files diverse. Therefore, a method for removing instrument response that is suitable for different instrument parameter file types is needed to meet the needs of earthquake data processing and further enhance earthquake monitoring capabilities. Summary of the invention

[0005] In view of the above problems, the present invention proposes a method for removing instrument response applicable to different parameter file formats, which can parse station parameter files in various formats and remove instrument response from waveform data.

[0006] The technical solution of the present invention is: a method for removing instrument response applicable to different parameter file formats, comprising the following specific steps:

[0007] Step 1: First, the instrument response parameter files are divided into four categories: the first category is the standard RESP and SACPZ formats, the second category is the paz format containing zero-pole information, the third category is the par format, and the fourth category is the fap format containing only frequency, amplitude and phase information; then determine the instrument response parameter file type;

[0008] Step 2: For the first three types of parameter file formats, zero-pole information, instrument sensitivity and normalization factor are extracted according to specific keywords, and the transfer function of the instrument response is calculated using the extracted information to obtain the amplitude-frequency response of the transfer function;

[0009] Step 3: For the fap format parameter file, extract the frequency, amplitude and phase information, calculate the amplitude-frequency response curve and perform interpolation so that the sampling point frequency of the curve is consistent with the spectrum of the waveform data;

[0010] Step 4: According to different instrument response types, different instrument response removal algorithms are used to obtain the processed waveform.

[0011] Beneficial effects: The present invention makes full use of the mathematical and physical principles of instrument response removal, summarizes and classifies the parameter file formats of different seismic stations, designs corresponding key parameter extraction methods and instrument response removal methods according to different format characteristics, so that the method is suitable for instrument response removal processing of waveform data of different seismic stations, and has the following characteristics:

[0012] (1) The types of seismic station parameter files currently encountered in seismic data processing were summarized and classified according to their file characteristics;

[0013] (2) A method for extracting instrument response parameters was designed based on the characteristics of the parameter file, which can calculate the transfer functions of different instrument responses;

[0014] (3) Based on the mathematical and physical principles of removing instrument response, corresponding algorithms are designed for different instrument response types, realizing the automated processing of removing instrument response from waveform data of different seismic stations. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a flow chart of an embodiment of the present invention.

[0016] Figure 2 1 is a comparison of the original waveform of the AAK station and the waveform after removing the instrument response (2-4 Hz filtering) in an embodiment of the present invention.

[0017] Figure 3 Comparison between the original waveform of the MKAR array and the waveform after removing the instrument response (2-4 Hz filtering) in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings and embodiments to make its technical content clearer and easier to understand. It should be noted that the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0019] like Figure 1 , the embodiment comprises the following steps:

[0020] Step 1: Determine the instrument response file type, where the instrument response of international public stations defaults to RESP type, and the instrument response type of IMS network stations is obtained from the database of the International Data Center (IDC).

[0021] The instrument response parameter file types are divided into four categories: the first category is the standard RESP and SACPZ formats, the second category is the paz format containing zero-pole information, the third category is the par format, and the fourth category is the fap format containing only frequency, amplitude and phase information;

[0022] In step one, the current station parameter file formats were summarized and classified, and corresponding key parameter extraction methods were designed according to different format characteristics, making this method applicable to the de-instrumentation response processing of all seismic stations.

[0023] Step 2: According to the instrument response type, select different parameter extraction algorithms to obtain the relevant parameters necessary for instrument response.

[0024] For the first three types of parameter file formats, zero-pole information, instrument sensitivity, and normalization factor are extracted according to specific keywords, and the transfer function of the instrument response is calculated using the extracted information to obtain the amplitude-frequency response of the transfer function; the details are as follows:

[0025] (2.1) For common parameter file formats such as RESP / SACPZ, the standard read method in the obspy software package is used to read the parameter file as an inventory object.

[0026] (2.2) For the parameter file in paz format (including paz, pazfir, firpaz, pazfap), open the file and read it line by line. Use the keyword "counts / " or "count / " to extract the calib value. Use "Sensitivity" to extract the sensitivity of each stage of the conversion from physical signal to digital signal. After multiplication, the total sensitivity S is obtained. d , extract the normalization factor A according to the position of the keyword "paz" 0 , and then extract the zero-pole value according to the number of zero-pole points in the downstream;

[0027] (2.3) For the par format file, the main steps are the same as the paz format, where the calib value of the instrument vertical channel is extracted according to the keywords "Z" and "ncalib", the reference period calibper is extracted according to "ncalper" and the reference frequency f is calculated. s . Further, the instrument sensitivity is calculated using the following formula:

[0028] S d =1 / (2πf s ·calib)

[0029] (2.4) The transfer function of the instrument response is calculated using the sensitivity, normalization factor, and zero-pole information as shown below:

[0030]

[0031] Where H(s) is the transfer function, s is the angular frequency (s = 2πf), f is the frequency, z is the zero value, and p 1 、p 2 is the extreme value, z 1 、z 2 The zero value point.

[0032] Step 3: extract the frequency, amplitude and phase information from the fap format file, calculate the amplitude-frequency response curve and perform interpolation so that the sampling point frequency of the curve is consistent with the spectrum of the waveform data;

[0033] Specifically: use the station name and channel name as keywords, combine the regular matching formulas 'is\d+\.\d+nm / count' and 'at\d+\d\d+Hz' to extract calib and calibper, calculate Sd according to the formula in (2.3), and use the "theoretical" and "fap" keywords to extract the frequency, amplitude and phase information in the downlink and save them as an array.

[0034] Step 4: Select different instrument response removal algorithms for different parameter file types to obtain processed waveforms, as follows:

[0035] (4.1) After removing the mean and linearity of the original waveform, perform N-point fast Fourier transform, where N is determined by the data length, and divide the sampling rate according to N to obtain a series of sampling point frequencies;

[0036] (4.2) For RESP / SACPZ format, use the read function to read it as an inventory object, and calculate the amplitude-frequency response of the transfer function according to the sampling point frequency in (4.1).

[0037] (4.3) For the paz and par formats, the extracted sensitivity, normalization factor and zero-pole information are defined as dictionaries, and the amplitude-frequency response of the transfer function is calculated according to the sampling point frequency in (4.1). The results are as follows: Figure 2 shown.

[0038] (4.4) For the fap format, the instrument response transfer function is interpolated according to the sampling point frequency in (4.1);

[0039] (4.5) At the corresponding frequency point, the complex amplitude of the waveform data is divided by the complex amplitude of the transfer function, and the result is inverse Fourier transformed to obtain the processed waveform data. The result is as follows Figure 3 shown.

[0040] Figure 2 This is a comparison of the original waveform of the AAK station in an embodiment of the present invention and the waveform after removing the instrument response (2-4Hz filtering). The parameter file format is pazfir. The upper figure is the original waveform, and the lower figure is the waveform after removing the instrument response. It can be seen that the waveform has not changed significantly, which is consistent with the characteristic that the instrument response is flat in the range of 2-4Hz.

[0041] Figure 3 This is a comparison of the original waveform of the MKAR array and the waveform after removing the instrument response (2-4 Hz filtering) in an embodiment of the present invention. The parameter file format is fap. The upper figure is the original waveform, and the lower figure is the waveform after removing the instrument response. It can be seen that the waveform has not changed significantly, which is consistent with the characteristic that the instrument response is flat in the range of 2-4 Hz.

Claims

1. A method for removing instrument response applicable to different parameter file formats, comprising the following specific steps: Step 1: First, the instrument response parameter files are divided into four categories: the first category is the standard RESP and SACPZ formats, the second category is the paz format containing zero-pole information, the third category is the par format, and the fourth category is the fap format containing only frequency, amplitude and phase information; then determine the instrument response parameter file type; Step 2: For the first three types of parameter file formats, zero-pole information, instrument sensitivity and normalization factor are extracted according to specific keywords, and the transfer function of the instrument response is calculated using the extracted information to obtain the amplitude-frequency response of the transfer function; Step 3: For the fap format parameter file, extract the frequency, amplitude and phase information, calculate the amplitude-frequency response curve and perform interpolation so that the sampling point frequency of the curve is consistent with the spectrum of the waveform data; Step 4: According to different instrument response types, different instrument response removal algorithms are used to obtain the processed waveform.

2. The method for removing instrument response applicable to different parameter file formats according to claim 1, characterized in that: In step one, the current station parameter file formats were summarized and classified, and corresponding key parameter extraction methods were designed according to different format characteristics, making this method applicable to the de-instrumentation response processing of all seismic stations.

3. The method for removing instrument response applicable to different parameter file formats according to claim 1, characterized in that: paz format parameter files include paz, pazfir, firpaz, and pazfap.

4. The method for removing instrument response applicable to different parameter file formats according to claim 1, characterized in that: In step 2, for the first three types of parameter file formats, the corresponding parameters are extracted according to the keyword information of different file formats, and the amplitude-frequency curve of the instrument response is calculated. The specific implementation method is as follows: (2.1) For parameter files in standard RESP and SACPZ formats, use the standard read method to read the parameter file as an inventory object; (2.2) For the parameter file in paz format, open the file and read it line by line. Use the keyword "counts / " or "count / " to extract the calib value. Use "Sensitivity" to extract the sensitivity of each stage of the conversion from physical signal to digital signal. After multiplication, the total sensitivity S is obtained. d , extract the normalization factor A0 according to the keyword "paz", and then extract the zero-pole value according to the number of zero-pole points in the downstream; (2.3) For the parameter file in par format, extract the calib value of the instrument vertical channel according to the keywords "Z" and "ncalib", extract the reference period calibper according to "ncalper" and calculate the reference frequency f s , further, the sensitivity of the instrument is calculated using the relationship between the two and the sensitivity: (2.4) Calculate the transfer function of the instrument response using sensitivity, normalization factor, and zero-pole information.

5. The method for removing instrument response applicable to different parameter file formats according to claim 4, characterized in that: The instrument sensitivity calculation formula is as follows: S d =1 / (2πf s ·calib)。 6. The method for removing instrument response applicable to different parameter file formats according to claim 4, characterized in that: The transfer function calculation formula is as follows: Where H(s) is the transfer function, s is the angular frequency, and p 1、 p2 is the extreme value, z 1、 z2 is the zero value point.

7. The method for removing instrument response applicable to different parameter file formats according to claim 5, characterized in that: In step 3, for the parameter file in fap format, the station name and channel name are used as keywords, and the regular matching formulas 'is\d+\.\d+nm / count' and 'at\d+\d\d+Hz' are combined to extract calib and calibper, and S is calculated. d , according to the "theoretical" and "fap" keywords, extract the frequency, amplitude, and phase information in the downstream and save them as an array.

8. The method for removing instrument response applicable to different parameter file formats according to claim 1, characterized in that: In step 4, different instrument response removal algorithms are set for different parameter file types. The specific implementation methods are as follows: (4.1) First, the original waveform is de-meaned and de-linearized, and then an N-point fast Fourier transform is performed. N is determined by the data length, and the sampling rate is divided according to N to obtain a series of sampling point frequencies; (4.2) For RESP or SACPZ format, use the read function to read it as an inventory object, and calculate the amplitude-frequency response of the transfer function according to the sampling point frequency in (4.1).

9. The method for removing instrument response applicable to different parameter file formats according to claim 8, characterized in that: In step (4.2), for paz and par formats, the extracted sensitivity, normalization factor and zero-pole information are defined as a dictionary, and the amplitude-frequency response of the transfer function is calculated according to the sampling point frequency in step (4.1); For the fap format, interpolate the instrument response transfer function according to the sampling point frequency in step (4.1).

10. The method for removing instrument response applicable to different parameter file formats according to claim 8, characterized in that: (4.3) At the corresponding frequency point, the complex amplitude of the waveform data is divided by the complex amplitude of the transfer function, and the result is inverse Fourier transformed to obtain the processed waveform data.

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