An airborne transient electromagnetic self-adaptive airborne acquisition method

Abstract

The application relates to a kind of air-ground transient electromagnetic self-adapting air collection methods, comprising: through transient electromagnetic receiver pre-collection time series data;The measured time series data is analyzed, and the adjacent two positive and negative extreme values are selected in the measured secondary field data, the time interval of the two places is divided by 2, and the time base parameter of the transmission waveform is obtained;Platform time period is identified in the measured signal, and the Ramp parameter in the transmission waveform corresponding to the time is obtained;The measured time series data is correlated with the standard secondary field periodic signal;Transient electromagnetic receiver starts synchronization according to the time base integer multiple of the starting time of transmission waveform, collects according to logarithmic interval window, superimposes data, and completes the data collection of one point;The receiver continues to collect on the flight platform according to the set route until the completion of all survey lines.The application can be compatible with multiple transmission systems, realize automatic analysis of transmission parameters under the condition of any ground system transmission, find the synchronous starting position and complete data collection.

Description

Technical Field

[0001] The present invention belongs to the technical field of geochemical exploration, and in particular relates to a ground-to-air transient electromagnetic adaptive aerial acquisition method. Background Art

[0002] Ground-to-air transient electromagnetic (GATEM) refers to a device that transmits transient electromagnetic signals from the ground and receives them in the air. It is a variant of ground-based transient electromagnetic (GATEM) and combines the advantages of GATEM's large transmission magnetic moment and deep detection with the rapid scanning speed of airborne transient electromagnetic (ATEM), while avoiding the inherent drawbacks of low ground acquisition efficiency and small transmission magnetic moment of ATEM. Therefore, GATEM holds great potential for applications in complex mountainous areas, such as tunnel surveys, geological disaster investigations, metal mines, and coal goafs.

[0003] However, the current ground-to-air transient electromagnetic method system requires strict synchronization between the airborne receiving subsystem and the ground transmitting subsystem. The purpose is to ensure that the airborne receiving subsystem always keeps the same time as the ground transmitting subsystem during the data acquisition process, so as to accurately determine the "on-time", "ramp" and "off-time" of the transmission waveform and select the appropriate time period for precise acquisition.

[0004] Currently, ground-based and aerial synchronization systems generally utilize high-precision GPS. However, different manufacturers and designers utilize different schemes for transmitting and receiving synchronization, creating invisible barriers to interoperability between different systems. An aerial receiving system based on a UAV flight platform can only capture the secondary field generated by the synchronously matched transmitting system, requiring a one-to-one correspondence between transmission and reception. This incompatibility between different systems results in significant waste. Summary of the Invention

[0005] The purpose of the present invention is to provide a ground-to-air transient electromagnetic adaptive aerial acquisition method that is compatible with multiple launch systems, can automatically analyze launch parameters under any ground system launch conditions, find the synchronization starting position and complete data acquisition.

[0006] The present invention provides a method for adaptive aerial acquisition of ground-to-air transient electromagnetic waves, comprising the following steps:

[0007] Step 1: pre-collecting time series data by means of a transient electromagnetic receiver; the transient electromagnetic receiver simultaneously satisfies both arithmetic equal interval and logarithmic equal interval data acquisition in the air;

[0008] Step 2: Analyze the measured time series data, select two adjacent positive and negative extreme values ​​in the measured secondary field data, divide the time interval between the two extreme values ​​by 2, and obtain the time base parameters of the emission waveform;

[0009] Step 3: Identify the platform time period in the measured signal and correspond this time period to the Ramp parameter in the transmission waveform;

[0010] Step 4: perform correlation analysis on the measured time series data and the standard secondary field periodic signal, where the maximum correlation coefficient corresponds to the starting time t0 of the emission waveform;

[0011] Step 5: Assign the time base, falling edge, and start time t0 of a complete waveform of the identified transmission waveform to the transient electromagnetic receiver to set acquisition parameters;

[0012] Step 6: The transient electromagnetic receiver starts synchronization based on the integer multiple of the time base of the start time of the transmitted waveform, collects data according to the logarithmic interval window, and superimposes the data a certain number of times to complete the data collection of one point;

[0013] Step 7: The transient electromagnetic receiver continues to collect data along the set route on the flight platform until all survey lines are completed.

[0014] Furthermore, in step 1, the transient electromagnetic receiver pre-collects time series data and collects time series signals at 4 μs intervals, and the collection time is 5 minutes.

[0015] By means of the above scheme, through the ground-to-air transient electromagnetic adaptive aerial acquisition method, analysis is carried out based on the measured transient response data, and an adaptive acquisition scheme is formulated. It can be compatible with most of the currently popular ground transient electromagnetic transmitters, can break through the problem of incompatibility between multiple ground-to-air transient electromagnetic systems, can use a single aerial receiving system to match most of the currently popular ground transmission systems, and reasonably use existing ground transmission systems of various powers (small, medium, large, and ultra-high power), which is conducive to the promotion and application of the ground-to-air transient electromagnetic method.

[0016] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the ground-to-air transient electromagnetic ground transmission waveform and the corresponding secondary field receiving signal in one embodiment of the present invention. DETAILED DESCRIPTION

[0018] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0019] Ginseng Figure 1 As shown, this embodiment provides a method for adaptive aerial acquisition of ground-to-air transient electromagnetic signals, including the following steps:

[0020] Step 1: pre-collecting time series data through a transient electromagnetic receiver; the transient electromagnetic receiver simultaneously satisfies both arithmetic equal interval and logarithmic equal interval data airborne collection; the receiver pre-collects time series data at 4 μs intervals to collect time series signals for 5 minutes;

[0021] Step 2: Analyze the measured time series data. Select two adjacent positive and negative extreme values ​​in the measured secondary field data, such as A' and D' in the attached figure. Divide the time interval between these two points by 2 to obtain the time base parameters of the transmission waveform. If the time interval between A' and D' is 20ms, then the time base parameters of the transmission waveform are 10ms.

[0022] Step 3: Identify the plateau period in the measured signal, such as the B'-C' segment in the attached figure, and map this period to the Ramp parameter in the transmit waveform. If the B'-C' interval is 50 μs, then the off-time parameter in the transmit waveform is also 50 μs.

[0023] Step 4: perform correlation analysis on the measured time series data (5-minute measured data) and the standard secondary field period signal (such as A'-F' in the attached figure), where the maximum correlation coefficient corresponds to the starting time t0 of the emission waveform;

[0024] Step 5: Assign the identified time base (10ms), falling edge (50μs) of the emission waveform, and the start time t0 of a complete waveform to the transient electromagnetic receiver to set acquisition parameters;

[0025] In step 6, the transient electromagnetic receiver begins synchronization based on integer multiples of the start time of the transmitted waveform, collects data in logarithmically spaced windows, and superimposes the data a certain number of times to complete data collection for one point. In this embodiment, the receiver begins synchronization based on integer multiples of the start time of the transmitted waveform, samples at 4μs intervals, and collects 26 time window channels at logarithmically equal intervals within each order of magnitude. The data is then superimposed 64 times to complete data collection for one point.

[0026] Step 7: The transient electromagnetic receiver continues to collect data along the set route on the flight platform until all survey lines are completed.

[0027] The present application can accurately give the starting time of the transmitting waveform by correlation analysis of pre-acquisition data; the time base and falling edge parameters of the transmitting waveform are obtained by peak value recognition in the pre-acquisition data; the transmitting waveform parameters obtained by pre-acquisition data analysis are automatically assigned to the airborne receiver, and acquisition is implemented. The method first obtains the starting position A of the transmitting waveform, the time base (TB) and the falling edge parameters (Ramp) of the transmitting waveform by waveform correlation analysis and peak value recognition of the pre-acquired time domain data, then starts acquisition in the Off-time period according to the starting position A as the starting time, the fixed time base (TB) and the logarithmic time window, and obtains the transient response curve at the measuring point by superimposing the data according to the set number of times.

[0028] The transient electromagnetic adaptive airborne acquisition system using the adaptive airborne acquisition method of ground-to-air transient electromagnetic system can match most popular transmitting systems, and accurately acquire secondary field data in the Off-time period according to the requirements.

[0029] The above description is only the preferred embodiments of the present application, and is not used to limit the present application, and it should be pointed out that, for ordinary skilled in the art, without departing from the technical principles of the present application, a number of improvements and modifications can be made, and these improvements and modifications should be considered as the protection scope of the present application.

Claims

1. A method for adaptive aerial acquisition of ground-to-air transient electromagnetic signals, characterized in that: The steps include: Step 1: pre-collecting time series data by means of a transient electromagnetic receiver; the transient electromagnetic receiver simultaneously satisfies both arithmetic equal interval and logarithmic equal interval data acquisition in the air; Step 2: Analyze the measured time series data, select two adjacent positive and negative extreme values ​​in the measured secondary field data, divide the time interval between the two extreme values ​​by 2, and obtain the time base parameters of the emission waveform; Step 3: Identify the platform time period in the measured signal and correspond this time period to the Ramp parameter in the transmission waveform; Step 4: perform correlation analysis on the measured time series data and the standard secondary field periodic signal, where the maximum correlation coefficient corresponds to the starting time t0 of the emission waveform; Step 5: Assign the time base, falling edge, and start time t0 of a complete waveform of the identified transmission waveform to the transient electromagnetic receiver to set acquisition parameters; Step 6: The transient electromagnetic receiver starts synchronization based on the integer multiple of the time base of the start time of the transmitted waveform, collects data according to the logarithmic interval window, and superimposes the data a certain number of times to complete the data collection of one point; Step 7: The transient electromagnetic receiver continues to collect data along the set route on the flight platform until all survey lines are completed.

2. The method for adaptive aerial acquisition of ground-to-air transient electromagnetic signals according to claim 1, characterized in that: In step 1, the transient electromagnetic receiver pre-collects time series data and collects time series signals at 4 μs intervals, with an acquisition time of 5 minutes.

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