A multi-band synchronous audio magnetotelluric acquisition system

Abstract

This invention discloses a multi-band synchronous audio-to-earth electromagnetic acquisition system, comprising a signal conditioning circuit module, an acquisition circuit module, a multi-channel acquisition control circuit, a processor, and a clock distribution circuit. The signal conditioning circuit module includes a radio frequency (RF) signal conditioning circuit, a high-frequency signal conditioning circuit, an intermediate frequency (IF) signal conditioning circuit, and a low-frequency signal conditioning circuit. The acquisition circuit module includes an RF signal acquisition circuit, a high-frequency signal acquisition circuit, an IF signal acquisition circuit, and a low-frequency signal acquisition circuit. The improvement lies in designing independent signal conditioning and acquisition circuits for each frequency band, and using a digital logic chip to perform clock distribution and synchronization, acquisition control, data aggregation and processing, and forwarding the aggregated data to the processor chip. Gain control is also performed on the signal conditioning circuits for the multiple frequency bands.

Description

Technical Field

[0001] This invention relates to the field of geological exploration technology, and in particular to a multi-band synchronous audio magnetotelluric acquisition system. Background Technology

[0002] Audio magnetotelluric (AMT) primarily relies on the resistivity differences between different geological bodies to make distinctions, and infers the spatial morphology of deep geological bodies based on the resistivity variation patterns within a certain range.

[0003] The signal strength of magnetotelluric signals varies across different frequency bands, and the sources of interference also differ. Therefore, the signal conditioning analog circuits of acquisition equipment are typically designed with three frequency bands: high, medium, and low. The acquisition device sequentially switches between these three frequency bands to acquire data in each band. Specifically, the acquisition method usually involves acquiring data in three frequency bands: band 1 (also known as high frequency), band 2 (also known as medium frequency), and band 3 (also known as low frequency), each corresponding to a different sampling frequency: band 1 typically has a sampling frequency of 1000–3000 Hz, band 2 typically has a sampling frequency of 100–300 Hz, and band 3 typically has a sampling frequency of 10–30 Hz. The acquisition method involves the magnetotelluric detector (instrument) and its acquisition software (software) first controlling the instrument's A / D converter to acquire the magnetotelluric signal in band 1. Since the sampling frequency is greater than 1000 Hz, data acquisition in band 1 can be completed within a few minutes. Then, the sampling frequency of the A / D converter is reduced to acquire the magnetotelluric signal in band 2. Signal acquisition in this frequency band can be completed within 30 minutes. Finally, magnetotelluric signals in frequency band 3 are acquired. Since magnetotelluric signals with a minimum frequency of 0.001Hz need to be acquired in this frequency band, the acquisition time is generally required to be more than 10 hours.

[0004] The current acquisition method does not achieve simultaneous (or continuous) acquisition of high, medium, and low frequencies. In signal acquisition, since the acquisition time of frequency band 1 is only a few minutes and the acquisition time of frequency band 2 is within 30 minutes, if strong interference is encountered during the acquisition process, it will seriously affect the acquisition quality of MT signal.

[0005] Therefore, it is necessary to provide a new multi-band synchronous audio magnetotelluric acquisition system. Summary of the Invention

[0006] The main objective of this invention is to provide a new multi-band synchronous audio magnetotelluric acquisition system to solve the aforementioned technical problems.

[0007] To achieve the above objectives, the present invention provides a multi-band synchronous audio magnetotelluric acquisition system, comprising a signal conditioning circuit module, an acquisition circuit module, a multi-channel acquisition control circuit, a processor, and a clock distribution circuit; wherein, the signal conditioning circuit module includes a radio frequency signal conditioning circuit, a high-frequency signal conditioning circuit, an intermediate frequency signal conditioning circuit, and a low-frequency signal conditioning circuit; the acquisition circuit module includes a radio frequency signal acquisition circuit, a high-frequency signal acquisition circuit, an intermediate frequency signal acquisition circuit, and a low-frequency signal acquisition circuit;

[0008] The clock distribution circuit includes a clock source unit, a multi-channel RF generator, an RF frequency distribution circuit, a high-frequency frequency distributor, an intermediate-frequency frequency distributor, and a low-frequency frequency distributor. The multi-channel RF generator generates clock frequency signals required by the acquisition circuits of different frequency bands in the acquisition circuit module based on the clock generated by the clock source unit. The RF frequency distribution circuit, the high-frequency frequency distributor, the intermediate-frequency frequency distributor, and the low-frequency frequency distributor are used to distribute each clock frequency signal to the corresponding acquisition circuit and conditioning circuit.

[0009] The multi-channel acquisition control circuit includes a communication unit for communicating with the processor, the acquisition circuit module, and the signal conditioning circuit module; sending gain control information from the channel configuration information sent by the processor to the signal conditioning circuit module; sending acquisition control signal parameters to the ADC chips of each acquisition circuit in the acquisition circuit module; and receiving the acquisition data from each channel acquired by the acquisition circuit module and transmitting it to the processor.

[0010] The multi-channel acquisition control circuit includes multiple buffers for storing the corresponding acquisition data from each channel;

[0011] The multi-channel acquisition control circuit uses a digital logic chip as the main controller to read the acquisition data from each channel. When all the acquisition data stored in the buffer meets the length of one frame, one frame of data is extracted from each channel to form a data packet. The acquisition control signal parameters and gain control information are then filled into the data packet, and the packet is sent to the processor through the communication unit.

[0012] Furthermore, the radio frequency signal conditioning circuit includes 4 to 6 radio frequency amplifiers, a high-pass filter and a driver amplifier; the high-frequency signal conditioning circuit includes 4 to 6 preamplifiers, a high-pass filter and a driver amplifier; the intermediate frequency signal conditioning circuit includes 4 to 6 preamplifiers, a band-pass filter and a driver amplifier; and the low-frequency signal conditioning circuit includes 4 to 6 chopper amplifiers, a power frequency filter, a low-pass filter and a driver amplifier.

[0013] Furthermore, the low-frequency signal acquisition circuit includes 4 to 6 low-frequency ADCs, with an acquisition frequency range of DC to 400Hz or 1kHz; the intermediate-frequency signal acquisition circuit includes 4 to 6 intermediate-frequency ADCs, with an acquisition frequency range of 400Hz or 1kHz to 4kHz; the high-frequency signal acquisition circuit includes 4 to 6 high-frequency ADCs, with an acquisition frequency range of 4kHz to 100kHz; and the radio frequency signal acquisition circuit includes 4 to 6 radio frequency ADCs, with an acquisition frequency range of 100kHz to 20MHz.

[0014] Furthermore, the clock source unit uses a low-jitter temperature-compensated crystal oscillator or a low-jitter temperature-controlled crystal oscillator as the clock source; the multi-channel RF generator uses a phase-locked loop clock synthesizer chip to generate the clock frequency signals required by the acquisition circuits of different frequency bands in the acquisition circuit module, and then uses a clock fan-out chip to fan out multiple clock frequency signals with the same frequency and phase from the clock frequency signal of one frequency band.

[0015] Furthermore, the multi-channel acquisition control circuit is also used to read the status of the ADC chip in each acquisition circuit of the acquisition circuit module, and send the status data of the ADC chip to the processor.

[0016] The multi-band synchronous audio-magnetic field acquisition system of this invention includes a signal conditioning circuit module, an acquisition circuit module, a multi-channel acquisition control circuit, a processor, and a clock distribution circuit. The signal conditioning circuit module includes a radio frequency (RF) signal conditioning circuit, a high-frequency signal conditioning circuit, an intermediate frequency (IF) signal conditioning circuit, and a low-frequency signal conditioning circuit. The acquisition circuit module includes an RF signal acquisition circuit, a high-frequency signal acquisition circuit, an IF signal acquisition circuit, and a low-frequency signal acquisition circuit. The improvement involves designing independent signal conditioning and acquisition circuits for each frequency band, and using a digital logic chip (FPGA / CLPD) to perform clock distribution and synchronization, acquisition control, data aggregation and processing, and forwarding the aggregated data to the processor chip. Gain control is also performed on the signal conditioning circuits for multiple frequency bands. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the module structure of a multi-band synchronous audio magnetotelluric acquisition system according to an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of the module structure of a low-frequency signal conditioning circuit in one embodiment of the present invention;

[0019] Figure 3 This is a schematic diagram of the module structure of the intermediate frequency signal conditioning circuit in one embodiment of the present invention;

[0020] Figure 4This is a schematic diagram of the module structure of a high-frequency signal conditioning circuit in one embodiment of the present invention;

[0021] Figure 5 This is a schematic diagram of the module structure of the radio frequency signal conditioning circuit in one embodiment of the present invention;

[0022] Figure 6 This is a schematic diagram of the module structure of the acquisition circuit module in one embodiment of the present invention;

[0023] Figure 7 This is a schematic diagram of the module structure of the clock distribution circuit in one embodiment of the present invention.

[0024] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Implementation

[0025] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0026] In the following description, the use of suffixes such as "module," "part," or "unit" to denote elements is solely for the purpose of illustrative purposes and has no specific meaning in itself. Therefore, "module," "part," or "unit" may be used interchangeably.

[0027] Please see Figure 1-7 To achieve the above objectives, an embodiment of the present invention provides a multi-band synchronous audio magnetotelluric acquisition system, comprising a signal conditioning circuit module, an acquisition circuit module, a multi-channel acquisition control circuit, a processor, and a clock distribution circuit; wherein, the signal conditioning circuit module includes a radio frequency signal conditioning circuit, a high-frequency signal conditioning circuit, an intermediate frequency signal conditioning circuit, and a low-frequency signal conditioning circuit; the acquisition circuit module includes a radio frequency signal acquisition circuit, a high-frequency signal acquisition circuit, an intermediate frequency signal acquisition circuit, and a low-frequency signal acquisition circuit.

[0028] Furthermore, the radio frequency signal conditioning circuit includes 4 to 6 radio frequency amplifiers, a high-pass filter and a driver amplifier; the high-frequency signal conditioning circuit includes 4 to 6 preamplifiers, a high-pass filter and a driver amplifier; the intermediate frequency signal conditioning circuit includes 4 to 6 preamplifiers, a band-pass filter and a driver amplifier; and the low-frequency signal conditioning circuit includes 4 to 6 chopper amplifiers, a power frequency filter, a low-pass filter and a driver amplifier.

[0029] Furthermore, the low-frequency signal acquisition circuit includes 4 to 6 low-frequency ADCs, with an acquisition frequency range of DC to 400Hz or 1kHz, preferably DC to 400Hz; the intermediate-frequency signal acquisition circuit includes 4 to 6 intermediate-frequency ADCs, with an acquisition frequency range of 400Hz or 1kHz to 4kHz, preferably 400kHz to 4kHz; the high-frequency signal acquisition circuit includes 4 to 6 high-frequency ADCs, with an acquisition frequency range of 4kHz to 100kHz; and the radio frequency signal acquisition circuit includes 4 to 6 radio frequency ADCs, with an acquisition frequency range of 100kHz to 20MHz.

[0030] The clock distribution circuit includes a clock source unit, a multi-channel RF generator, an RF frequency distribution circuit, a high-frequency frequency distributor, an intermediate-frequency frequency distributor, and a low-frequency frequency distributor. The multi-channel RF generator generates clock frequency signals required by the acquisition circuits of different frequency bands in the acquisition circuit module based on the clock generated by the clock source unit. The RF frequency distribution circuit, the high-frequency frequency distributor, the intermediate-frequency frequency distributor, and the low-frequency frequency distributor are used to distribute each clock frequency signal to the corresponding acquisition circuit and conditioning circuit.

[0031] Furthermore, the clock source unit uses a low-jitter temperature-compensated crystal oscillator or a low-jitter temperature-controlled crystal oscillator as the clock source; the multi-channel RF generator uses a phase-locked loop (PLL) clock synthesizer chip to generate the clock frequency signals required by the acquisition circuits of different frequency bands in the acquisition circuit module, and then uses a clock fan-out chip to fan out multiple clock frequency signals with the same frequency and phase for a single frequency band. Specifically, a low-jitter temperature-compensated crystal oscillator or a low-jitter temperature-controlled crystal oscillator is used as the clock source, and a phase-locked loop (PLL) clock synthesizer chip is used to generate the clock frequencies required by the ADCs of different frequency band acquisition circuits. The clock frequencies of different frequency bands are different, but because they are generated from the same clock source, these clocks of different frequencies are synchronized. Then, for a single frequency band clock signal, a clock fan-out chip is used to fan out multiple clock signals with the same frequency and phase for use by the multiple ADCs of that frequency band. Each frequency distributor distributes one clock into 4-6 clocks to control each acquisition circuit ADC.

[0032] The multi-channel acquisition control circuit includes a communication unit for communicating with the processor, the acquisition circuit module, and the signal conditioning circuit module; sending gain control information from the channel configuration information sent by the processor to the signal conditioning circuit module; sending acquisition control signal parameters to the ADC chips of each acquisition circuit in the acquisition circuit module; and receiving the acquisition data from each channel acquired by the acquisition circuit module and transmitting it to the processor.

[0033] The multi-channel acquisition control circuit includes multiple buffers for storing the corresponding acquisition data from each channel;

[0034] A digital logic chip is used as the main controller to read the data from each channel. When all the data from each channel stored in the buffer meets the length of one frame, one frame of data is extracted from each channel to form a data packet. The data packet is then filled with the acquisition control signal parameters and gain control information and sent to the processor through the communication unit.

[0035] The multi-channel acquisition control circuit uses a programmable digital logic chip (FPGA / CPLD) as the acquisition controller, which is used for:

[0036] Receive channel configuration information sent by the processor, including gain control information and acquisition control information;

[0037] Send gain control signals to each signal conditioning circuit;

[0038] Send acquisition control parameters to the ADC chips of each acquisition circuit;

[0039] Synchronously send acquisition start signals to the ADC chips of each acquisition circuit;

[0040] The data collected by the ADC chips of each acquisition circuit is entered into the buffer.

[0041] When each data buffer is sufficient for one frame of data length, one frame of data is extracted from each buffer to form a data packet.

[0042] Fill the data packets with gain control information and acquisition control information;

[0043] Data packets are transmitted to the processor via communication circuitry.

[0044] Furthermore, the multi-channel acquisition control circuit is also used to read the status of the ADC chip in each acquisition circuit of the acquisition circuit module, and send the status data of the ADC chip to the processor.

[0045] Specifically, the acquisition control process of the multi-channel acquisition control circuit includes:

[0046] 1) The processor controls the power-on of the acquisition system and waits for the clock signal to stabilize;

[0047] 2) The processor sends gain control information and acquisition control information to the multi-channel acquisition control circuit according to the user settings;

[0048] 2.1) The multi-channel acquisition control circuit sets gain control signals for all signal conditioning circuit channels;

[0049] 2.2) The multi-channel acquisition control circuit sets the acquisition control parameters for the ADCs of all signal acquisition circuits;

[0050] 2.3) The multi-channel acquisition control circuit reads the status of all signal acquisition circuits' ADCs and sends the ADC status data to the processor;

[0051] 3) The processor sends a start acquisition command to the multi-channel acquisition control circuit according to the user settings;

[0052] 3.1) If the acquisition start command is "Acquisition Start," the multi-channel acquisition control circuit will immediately send a signal to acquire the data;

[0053] 3.2) If the acquisition start command is a timed acquisition, the multi-channel acquisition control circuit will send a signal to acquire the data when the timer arrives.

[0054] The multi-band synchronous audio-magnetic field acquisition system of this invention includes a signal conditioning circuit module, an acquisition circuit module, a multi-channel acquisition control circuit, a processor, and a clock distribution circuit. The signal conditioning circuit module includes a radio frequency (RF) signal conditioning circuit, a high-frequency signal conditioning circuit, an intermediate frequency (IF) signal conditioning circuit, and a low-frequency signal conditioning circuit. The acquisition circuit module includes an RF signal acquisition circuit, a high-frequency signal acquisition circuit, an IF signal acquisition circuit, and a low-frequency signal acquisition circuit. The improvement involves designing independent signal conditioning and acquisition circuits for each frequency band, and using a digital logic chip (FPGA / CLPD) to perform clock distribution and synchronization, acquisition control, data aggregation and processing, and forwarding the aggregated data to the processor chip. Gain control is also performed on the signal conditioning circuits for multiple frequency bands.

[0055] In the description of this specification, references to terms such as "one embodiment," "another embodiment," "other embodiments," or "first embodiment to Xth embodiment," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, method steps, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0056] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0057] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A multi-band synchronous audio magnetotelluric acquisition system, characterized in that, It includes a signal conditioning circuit module, an acquisition circuit module, a multi-channel acquisition control circuit, a processor, and a clock distribution circuit; wherein, the signal conditioning circuit module includes a radio frequency signal conditioning circuit, a high-frequency signal conditioning circuit, an intermediate frequency signal conditioning circuit, and a low-frequency signal conditioning circuit; the acquisition circuit module includes a radio frequency signal acquisition circuit, a high-frequency signal acquisition circuit, an intermediate frequency signal acquisition circuit, and a low-frequency signal acquisition circuit; The clock distribution circuit includes a clock source unit, a multi-channel RF generator, an RF frequency distribution circuit, a high-frequency frequency distributor, an intermediate-frequency frequency distributor, and a low-frequency frequency distributor. The multi-channel RF generator generates clock frequency signals required by the acquisition circuits of different frequency bands in the acquisition circuit module based on the clock generated by the clock source unit. The RF frequency distribution circuit, the high-frequency frequency distributor, the intermediate-frequency frequency distributor, and the low-frequency frequency distributor are used to distribute each clock frequency signal to the corresponding acquisition circuit and conditioning circuit. The multi-channel acquisition control circuit includes a communication unit for communicating with the processor, the acquisition circuit module, and the signal conditioning circuit module; sending gain control information from the channel configuration information sent by the processor to the signal conditioning circuit module; sending acquisition control signal parameters sent by the processor to the ADC chips of each acquisition circuit in the acquisition circuit module; and receiving the acquisition data acquired by the acquisition circuit module and transmitting it to the processor. The multi-channel acquisition control circuit includes multiple buffers for storing the corresponding acquisition data from each channel; The multi-channel acquisition control circuit uses a digital logic chip as the main controller to read the acquisition data from each channel. When all the acquisition data stored in the buffer meets the length of one frame, one frame of data is extracted from each channel to form a data packet. The acquisition control signal parameters and gain control information are then filled into the data packet, and the packet is sent to the processor through the communication unit. The radio frequency signal conditioning circuit includes 4 to 6 radio frequency amplifiers, a high-pass filter and a driver amplifier; the high-frequency signal conditioning circuit includes 4 to 6 preamplifiers, a high-pass filter and a driver amplifier; the intermediate frequency signal conditioning circuit includes 4 to 6 preamplifiers, a band-pass filter and a driver amplifier; and the low-frequency signal conditioning circuit includes 4 to 6 chopper amplifiers, a power frequency filter, a low-pass filter and a driver amplifier. The low-frequency signal acquisition circuit includes 4 to 6 low-frequency ADCs, with an acquisition frequency range of DC to 400Hz or 1kHz; the intermediate-frequency signal acquisition circuit includes 4 to 6 intermediate-frequency ADCs, with an acquisition frequency range of 400Hz or 1kHz to 4kHz; the high-frequency signal acquisition circuit includes 4 to 6 high-frequency ADCs, with an acquisition frequency range of 4kHz to 100kHz; the radio frequency signal acquisition circuit includes 4 to 6 radio frequency ADCs, with an acquisition frequency range of 100kHz to 20MHz. The clock source unit uses a low-jitter temperature-compensated crystal oscillator or a low-jitter temperature-controlled crystal oscillator as the clock source; the multi-channel RF generator uses a phase-locked loop clock synthesizer chip to generate the clock frequency signals required by the acquisition circuits of different frequency bands in the acquisition circuit module, and then uses a clock fan-out chip to fan out multiple clock frequency signals with the same frequency and phase for a clock frequency signal of one frequency band. The multi-channel acquisition control circuit is also used to read the status of the ADC chip in each acquisition circuit of the acquisition circuit module and send the status data of the ADC chip to the processor.

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