CN218071449U - Electric field signal program control gain ultra-low noise acquisition system - Google Patents
Electric field signal program control gain ultra-low noise acquisition system Download PDFInfo
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- CN218071449U CN218071449U CN202222121714.0U CN202222121714U CN218071449U CN 218071449 U CN218071449 U CN 218071449U CN 202222121714 U CN202222121714 U CN 202222121714U CN 218071449 U CN218071449 U CN 218071449U
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Abstract
The utility model discloses an electric field signal program control gain ultra-low noise acquisition system, which comprises a low noise amplification acquisition circuit and an FPGA controller connected with the low noise amplification acquisition circuit; the low-noise amplification acquisition circuit comprises a modulation unit, an isolation transformer, a primary amplification circuit, a program-controlled gain unit, an analog demodulation unit, a low-pass filter circuit, a secondary amplification circuit and an analog-to-digital conversion circuit; the low-noise operational amplifier is used as a core, a resistance network in a D/A converter is used as a feedback resistor, a circuit gain adjustment electric field signal amplification acquisition circuit is carried out by changing the digital control force of the D/A converter, the low-noise chopping amplification principle is adopted, a program control gain unit adopts the design scheme that the low-noise operational amplifier is used as the core and the resistance network in the D/A converter is used as the feedback resistor, and the resistance value of the D/A internal resistance network is controlled through the digital control quantity to realize the gain change of the system.
Description
Technical Field
The utility model relates to an electric field signal programme-controlled gain ultralow noise collection technical field especially relates to an electric field signal programme-controlled gain ultralow noise collection system.
Background
China has a wide ocean area and abundant ocean oil and gas resources. In the process of detecting ocean oil and gas resources, in the face of increasingly complex detection objects, the traditional two-single three-dimensional seismic detection gradually seems to be careless.
The marine electromagnetic surveying method is used as an important supplementary means for marine seismic exploration, has high-resistance anomaly recognition capability, can judge whether oil or water exists in a reservoir, plays an increasingly important role in detection and estimation of oil and gas resources, and becomes one of the emerging services developed by various geophysical exploration companies all over the world.
The marine electromagnetic acquisition recorder is one of important technical equipment for marine electromagnetic prospecting, and has already entered the popularization and application stage after great development abroad.
The ultra-low noise amplification of weak electric field signals is one of the core technologies of marine electromagnetic acquisition recorders. Marine electromagnetic surveying methods divided by field source are classified into Magnetotelluric (MT) methods and CSEM methods. The MT method takes natural electromagnetic waves as field source signals, and because the electromagnetic waves of seawater are attenuated, the electromagnetic waves of the seabed and the earth are low-frequency, and are commonly used for deep seabed detection. The CSEM method uses artificially emitted electromagnetic waves as field source signals, can be considered to adjust the emission frequency and intensity of the field source signals, and can be used for shallow seabed exploration. The fixed gain marine electric field signal acquisition mode cannot completely meet the requirement of submarine electromagnetic exploration.
Aiming at different circuit gain requirements, the solution of fixed gain is to replace a pre-amplification circuit or adopt a dual-gain pre-amplification circuit in the exploration operation process. The circuit replacement mode has large workload and low efficiency on a construction site; the dual gain circuit approach results in increased instrument size and power consumption.
SUMMERY OF THE UTILITY MODEL
The utility model aims to solve the technical problem that to weak dynamic electric field signal's wide measuring range demand in the marine electromagnetic exploration, provide an electric field signal programme-controlled gain ultralow noise collection system, it uses low noise operational amplifier as the core, carries out the circuit gain adjustment through changing D/A converter digital control power as feedback resistance with D/A converter internal resistance network.
The utility model discloses a solve above-mentioned technical problem and adopt following technical scheme:
an electric field signal program-controlled gain ultra-low noise acquisition system comprises a low noise amplification acquisition circuit and a signal acquisition circuit connected with the low noise amplification acquisition circuit
An FPGA controller;
the low-noise amplification acquisition circuit comprises a modulation unit, an isolation transformer, a primary amplification circuit, a program-controlled gain unit, an analog demodulation unit, a low-pass filter circuit, a secondary amplification circuit and an analog-to-digital conversion circuit;
the FPGA controller comprises a modulation and demodulation logic module, a program control gain logic module, an A/D acquisition module and an ARM controller;
the radio wave signal is connected with an A/D acquisition module through a control unit, an isolation transformer, a primary amplification circuit, a program control gain unit, an analog demodulation unit, a low-pass filter circuit, a secondary amplification circuit and an analog-to-digital conversion circuit in sequence, the modulation-demodulation logic module, the program control gain logic module and the A/D acquisition module are respectively connected with an ARM controller, the modulation-demodulation logic module is connected with the modulation unit through a first modulation signal driving module, the modulation-demodulation logic module is connected with the analog demodulation unit through a second modulation signal driving module, and the program control gain logic module is connected with the program control gain unit;
the modulation unit is used for adjusting the electric field signal;
the isolation transformer is used for realizing the matching of the high input impedance of the amplifying circuit and the low input impedance of the electric field sensor;
the primary amplifying circuit is used for amplifying the ultralow noise of the electric field signal;
the program control gain unit is used for forgetting a resistor in the high-precision D/A converter as a feedback resistor, obtaining different resistance values by controlling the D/A converter and realizing different gain amplification of the primarily amplified electric field signal;
the analog demodulation unit controls the connection form of the input end of the amplifier through a digital switch, and alternately forms a follower and an inverter to realize the analog demodulation of signals;
the low-pass filter circuit is used for carrying out noise suppression on the burr signals generated in the demodulation process;
a secondary amplifying circuit, a voltage follower composed of an operational amplifier, for high output impedance;
the analog-to-digital conversion circuit is used for performing analog-to-digital conversion on the electric field signal;
the modulation and demodulation logic module is used for generating high-frequency square waves as modulation signals and demodulation signals;
the programmable gain logic module is used for controlling the internal resistance network of the D/A converter of the programmable gain unit to generate different resistance values;
and the A/D acquisition module is used for acquiring logic control A/D conversion process and acquiring electric field digital signals.
As a further preferred aspect of the electric field signal program-controlled gain ultra-low noise acquisition system, the program control
The gain unit comprises an ultra-low noise integrated operational amplifier and a 16-bit high precision D/A converter,
as a further preferable solution of the electric field signal program control gain ultra-low noise collection system of the present invention, the modulation unit comprises a bridge circuit formed by four identical JET tubes.
As a further preferred scheme of the ultralow noise collection system of electric field signal program-controlled gain, isolation transformer adopts small-signal audio frequency transformer module.
As a further preferred scheme of the ultralow noise collection system of electric field signal program-controlled gain, the low noise operational amplifier of modulation signal frequency channel is chooseed for use to elementary amplifier circuit.
The utility model adopts the above technical scheme to compare with prior art, have following technological effect:
the utility model relates to an ultralow noise collection system of programme-controlled gain of electric field signal, it uses low noise operational amplifier as the core, regard DA converter internal resistance network as feedback resistance, carry out circuit gain adjustment electric field signal amplification collection circuit through changing DA converter digital control power and adopt the low noise chopping amplification principle, programme-controlled gain unit adopts and is the core with low noise operational amplifier, DA converter internal resistance network is as feedback resistance's design, control DA internal resistance network resistance through digital control volume and realize that system gain changes.
Drawings
FIG. 1 is a schematic diagram of the electric field signal program-controlled gain ultra-low noise acquisition system of the present invention;
fig. 2 is a circuit diagram of the programmable gain unit of the present invention;
fig. 3 is a circuit diagram of the low noise amplification and acquisition circuit of the present invention.
Detailed Description
The technical scheme of the utility model is further explained in detail with the attached drawings as follows:
the present invention is described in terms of specific embodiments, and other advantages and benefits of the present invention will become apparent to those skilled in the art from the following disclosure. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
An electric field signal program-controlled gain ultra-low noise acquisition system comprises a low noise amplification acquisition circuit and a signal acquisition circuit connected with the low noise amplification acquisition circuit
An FPGA controller;
the low-noise amplification acquisition circuit comprises a modulation unit, an isolation transformer, a primary amplification circuit, a program-controlled gain unit, an analog demodulation unit, a low-pass filter circuit, a secondary amplification circuit and an analog-to-digital conversion circuit;
the FPGA controller comprises a modulation-demodulation logic module, a program control gain logic module, an A/D acquisition module and an ARM controller;
the radio wave signal sequentially passes through a modulation unit, an isolation transformer, a primary amplification circuit, a program control gain unit, an analog demodulation unit, a low-pass filter circuit, a secondary amplification circuit and an analog-to-digital conversion circuit to be connected with an A/D acquisition module, the modulation-demodulation logic module, the program control gain logic module and the A/D acquisition module are respectively connected with an ARM controller, the modulation-demodulation logic module is connected with the modulation unit through a first modulation signal driving module, the modulation-demodulation logic module is connected with the analog demodulation unit through a second modulation signal driving module, and the program control gain logic module is connected with the program control gain unit;
the modulation unit is used for adjusting an electric field signal; the modulation unit is a bridge circuit consisting of four identical JET tubes.
The isolation transformer is used for realizing the matching of the high input impedance of the amplifying circuit and the low input impedance of the electric field sensor; the described
The isolation transformer adopts a small-signal audio transformer module.
The primary amplifying circuit is used for amplifying the ultralow noise of the electric field signal; the primary amplifying circuit selects a low-noise operational amplifier for modulating a signal frequency band.
The program control gain unit is used for forgetting a resistor in the high-precision D/A converter as a feedback resistor, obtaining different resistance values by controlling the D/A converter and realizing different gain amplification of the primarily amplified electric field signal;
the analog demodulation unit controls the connection form of the input end of the amplifier through a digital switch, and alternately forms a follower and an inverter to realize the analog demodulation of signals;
the low-pass filter circuit is used for carrying out noise suppression on the burr signals generated in the demodulation process;
a secondary amplifying circuit, a voltage follower composed of an operational amplifier, for high output impedance;
the analog-to-digital conversion circuit is used for performing analog-to-digital conversion on the electric field signal;
the modulation and demodulation logic module is used for generating high-frequency square waves as modulation signals and demodulation signals;
the programmable gain logic module is used for controlling the internal resistance network of the D/A converter of the programmable gain unit to generate different resistance values;
and the A/D acquisition module is used for acquiring logic control A/D conversion process and acquiring electric field digital signals.
The utility model relates to a modulation unit, isolation transformer, primary amplifier circuit, programme-controlled gain unit, analog demodulation unit, low pass filter circuit, secondary amplifier circuit and analog-to-digital conversion circuit, modem logic module, programme-controlled gain logic module, AD acquisition module and ARM controller;
the above unit modules are all the prior art and are not the point of the invention. The unit modules are all the processing of the product, which is not the invention point of the utility model.
As shown in fig. 2, the programmable gain unit comprises an ultra-low noise integrated operational amplifier and a 16-bit high precision D/a converter,
a resistor Rpg with a fixed resistance value of 7 kilohms is connected between a pin RFB and an OUT of a D/A converter in the unit, a T-type R-2R resistor network Rx is arranged inside the pin VREF and the OUT, and a digital control quantity n is configured for an internal register of the D/A converter, so that the internal resistor network Rx has different resistance values. The internal resistance network Rx of the D/A converter is used as the feedback resistance of the operational amplifier to realize the digital controllable gain amplification.
As shown in fig. 3, the modulation unit is equivalent to a switch S0 connected in series with a resistor Rm; t1 is an isolation transformer, and the isolation transformer,
the primary amplification is carried out, C0 and R1 form a low-pass filter, G1 is a low-noise operational amplifier, rf1 and Rf2 are feedback resistors, and R2 is an operational amplifier input end resistor;
the program control gain unit takes an operational amplifier G2 as a core, a D/A internal resistance network Rx as a feedback resistor and Rpg as an input end resistor of the operational amplifier;
the demodulation unit takes an operational amplifier G3 as a core, controls the connection form of the input end through an equivalent electronic switch S1, and alternately forms a follower and a phase inverter, wherein R3 is the resistance of the input end of the operational amplifier, and R4 and R5 are feedback resistances;
low-pass filtering, namely forming a second-order low-pass filter by using R6, C1, C7 and C2; then
Stage amplification, wherein the operational amplifier G4 forms a voltage follower; the secondary amplified output signal is input to an A/D converter.
The on-resistance of a single field effect transistor of the modulation unit and the bridge type switching circuit is 3 ohms, so that the modulation unit can be equivalent to a resistance Rm of 6 ohms, and the corresponding resistance thermal noise is Vm.
In the primary amplification and low-pass filter part, because the effective electric field signal frequency band is in the same frequency band of the low-pass filter, the capacitor Co is short-circuited, so the resistor R1 is equivalent to an unconnected circuit, and the resistance noise is 0. In the primary amplification, amplifier G1, input resistor R2=10 ohms, and its resistive thermal noise is V2.
The program control gain is the same as the primary amplifier in the operational amplifier, and the gain amplification factor of the corresponding input end of the program control gain unit is 100 times after the amplification of the isolation transformer and the amplification of the primary amplifier.
The resistance R3=56.2 kilo-ohm at the input end of the demodulation unit, amplifier G3, and the resistance thermal noise is V3.
Secondary amplification and no resistance thermal noise. The operational amplifier G4 and the demodulation unit are the same, the input noise voltage Vne4 and the input current noise density in4 are small, and the gain amplification factor of the corresponding input end is large, so the background noise generated by the input current noise can be ignored.
Ultra-low noise amplification of marine electric field signals is one of the core technologies for marine electromagnetic surveying. Aiming at the program control gain requirement of electric field signal ultra-low noise amplification in marine electromagnetic exploration, the electric field signal program control gain ultra-low noise acquisition system is provided, the system main control adopts a low-power ARM + FPGA design, ARM realizes the management decision of system tasks, and FPGA is responsible for the synchronous acquisition control of a plurality of acquisition channels. Aiming at the characteristic that electric field signals are weak at low frequency, the electric field signal amplification and acquisition circuit adopts a low-noise chopping amplification principle. The program control gain unit adopts a design scheme that a low-noise operational amplifier is used as a core and a D/A converter internal resistance network is used as a feedback resistor, and the digital control quantity is used for controlling the resistance value of the D/A converter internal resistance network to realize system gain change.
Claims (5)
1. The utility model provides an electric field signal program control gain ultra-low noise collection system which characterized in that: the low-noise amplifier comprises a low-noise amplification acquisition circuit and an FPGA controller connected with the low-noise amplification acquisition circuit;
the low-noise amplification acquisition circuit comprises a modulation unit, an isolation transformer, a primary amplification circuit, a program-controlled gain unit, an analog demodulation unit, a low-pass filter circuit, a secondary amplification circuit and an analog-to-digital conversion circuit;
the FPGA controller comprises a modulation-demodulation logic module, a program control gain logic module, an A/D acquisition module and an ARM controller;
the radio wave signal is connected with an A/D acquisition module through a control unit, an isolation transformer, a primary amplification circuit, a program control gain unit, an analog demodulation unit, a low-pass filter circuit, a secondary amplification circuit and an analog-to-digital conversion circuit in sequence, the modulation-demodulation logic module, the program control gain logic module and the A/D acquisition module are respectively connected with an ARM controller, the modulation-demodulation logic module is connected with the modulation unit through a first modulation signal driving module, the modulation-demodulation logic module is connected with the analog demodulation unit through a second modulation signal driving module, and the program control gain logic module is connected with the program control gain unit;
the modulation unit is used for adjusting the electric field signal;
the isolation transformer is used for realizing the matching of the high input impedance of the amplifying circuit and the low input impedance of the electric field sensor;
the primary amplifying circuit is used for ultralow noise amplification of the electric field signal;
the program control gain unit is used for forgetting a resistor in the high-precision D/A converter as a feedback resistor, obtaining different resistance values by controlling the D/A converter and realizing different gain amplification of the primarily amplified electric field signal;
the analog demodulation unit controls the connection form of the input end of the amplifier through a digital switch, and alternately forms a follower and an inverter to realize the analog demodulation of signals;
the low-pass filter circuit is used for carrying out noise suppression on the burr signals generated in the demodulation process;
a secondary amplifying circuit, a voltage follower composed of an operational amplifier, for high output impedance;
the analog-to-digital conversion circuit is used for performing analog-to-digital conversion on the electric field signal;
the modulation and demodulation logic module is used for generating high-frequency square waves as modulation signals and demodulation signals;
the programmable gain logic module is used for controlling the internal resistance network of the D/A converter of the programmable gain unit to generate different resistance values;
and the A/D acquisition module is used for acquiring logic control A/D conversion process and acquiring electric field digital signals.
2. The system of claim 1, wherein the programmable gain ultra-low noise signal acquisition unit comprises: the program-controlled gain unit comprises an ultra-low noise integrated operational amplifier and a 16-bit high-precision D/A converter.
3. The electric field signal programmable gain ultra-low noise acquisition system of claim 1, wherein: the modulation unit is a bridge circuit consisting of four identical JET tubes.
4. The electric field signal programmable gain ultra-low noise acquisition system of claim 1, wherein: the isolation transformer adopts a small-signal audio transformer module.
5. The electric field signal programmable gain ultra-low noise acquisition system of claim 1, wherein: the primary amplifying circuit selects a low-noise operational amplifier for modulating a signal frequency band.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202222121714.0U CN218071449U (en) | 2022-08-12 | 2022-08-12 | Electric field signal program control gain ultra-low noise acquisition system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202222121714.0U CN218071449U (en) | 2022-08-12 | 2022-08-12 | Electric field signal program control gain ultra-low noise acquisition system |
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| CN218071449U true CN218071449U (en) | 2022-12-16 |
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| CN202222121714.0U Active CN218071449U (en) | 2022-08-12 | 2022-08-12 | Electric field signal program control gain ultra-low noise acquisition system |
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