CN209727812U - A kind of compressed sensing based NMR signal acquisition device - Google Patents
A kind of compressed sensing based NMR signal acquisition device Download PDFInfo
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- CN209727812U CN209727812U CN201920293013.0U CN201920293013U CN209727812U CN 209727812 U CN209727812 U CN 209727812U CN 201920293013 U CN201920293013 U CN 201920293013U CN 209727812 U CN209727812 U CN 209727812U
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Abstract
The utility model belongs to nuclear magnetic resonance Underground water instrument field, more particularly to a kind of compressed sensing based NMR signal acquisition device, the signal pre-processing circuit that the device is connected by being transferred to rear end after receiving coil reception electromagnetic signal, signal pre-processing circuit, electromagnetic signal is amplified and is filtered by the signal pre-processing circuit, so that treated, signal magnitude is suitble to AD sampling, signal after signal pre-processing circuit is transmitted in analog multiplier connected to it, one input terminal of the analog multiplier also passes through the output end that subtracter is connected to control system, after the output end of the analog multiplier is connect with integrating circuit, signal is transmitted to control system by low speed ADC sample circuit after integrating circuit, the R connected via the output end of control system For S485 circuit transmission into PC, sampling rate when the utility model acquires signal is far below the sample rate of original signal, further decreases to the memory requirement of sampling apparatus.
Description
Technical field
The utility model belongs to nuclear magnetic resonance Underground water instrument field more particularly to a kind of compressed sensing based core
Acquisition of magnetic resonance signals device.
Background technique
The occupancy volume per person of CHINESE FRESHWATER resource is only equivalent to the 1/4 of world occupancy volume per person, and distribution of water resources and its
Unevenly, so that the detection of underground water becomes particularly important.Nuclear magnetic resonance Bathymetric Technology is currently the only a kind of directly effective
The geophysical exploration method of Underground water.The basic principle is that generated by Hydrogen Proton resonant transition in Underground water
NMR signal come realize underground water detect.But collected NMR signal is very faint, is nV grade, it is easy
By the noise jamming in environment, meanwhile, it is excessive based on traditional collected data volume of Nyquist sample rate, to experiment instrument
The data storage and data transmission of device cause very big pressure.
Utility model content
The technical problem to be solved by the utility model is to provide a kind of compressed sensing based NMR signals to adopt
Acquisition means solve the collected signal of current nuclear magnetic resonance apparatus and contain too many redundancy, while device sampling rate mistake
High bring power consumption is excessively high, is unfavorable for the long-time acquisition signal in field, meanwhile, the compressed signal of acquisition is subsequent realization nothing
Line transmission lays the foundation.
The utility model is realized in this way a kind of compressed sensing based NMR signal acquisition device, the device
It include: receiving coil, signal pre-processing circuit, analog multiplier, integrating circuit, low speed ADC sample circuit, FPGA control list
Member, RS485 circuit and subtracter, in which: the signal by being transferred to rear end connection after receiving coil reception electromagnetic signal is located in advance
Circuit is managed, signal pre-processing circuit, electromagnetic signal is amplified and filtered by the signal pre-processing circuit, so that treated
Signal magnitude is suitble to AD sampling, and the signal after signal pre-processing circuit is transmitted in analog multiplier connected to it, institute
The input terminal for stating analog multiplier also passes through the output end that subtracter is connected to control system, the analog multiplier
After output end is connect with integrating circuit, signal is transmitted to FPGA control by low speed ADC sample circuit after integrating circuit
Unit processed, the RS485 circuit transmission connected via the output end of control system is into PC.
Further, the receiving coil is made an uproar using the square coil of 100m × 100m as electromagnetism in environment is received
The coil of sound.
Further, the signal pre-processing circuit includes preamplifier and bandpass filter, and preamplifier includes
The LT1028 of three low noises is composed in series after far calculating amplifier in parallel with a LT1028 operational amplifier, preamplifier
Output end is connected to a bandwidth-limited circuit, and band-pass circuit is far calculated the low-pass filter group that amplifier is constituted by two LT1028
At cutoff frequency is 3kHz and high-pass filtering composition, cutoff frequency 1kHz, so that the range of the bandpass filter of composition
Between 1kHz-3kHz.
Further, the analog multiplier uses AD633 model chip.
Further, the integrating circuit includes using two panels AD823 transport and placing device, is connected by auxiliary resistance and capacitor series connection
It connects.
Further, the low speed ADC sample circuit uses 8 analog-digital converters of ADC0809 model.
Further, the control system selects the EP2C8Q208C8N of Alteral company.
Further, the RS485 circuit uses P485R chip, RXD the and TXD pin point of control system circuit
It is not connected with the RO pin of SP485R circuit and DI pin.
Compared with prior art, beneficial effect is the utility model: the utility model, will by way of compression sampling
The analog signal projection dimensionality reduction of higher-dimension is to low-dimensional, so that required sampling rate substantially reduces, well below original signal institute
The sample rate needed reduces the requirement of hardware collecting part, so that system power dissipation reduces, is conducive to the prolonged data in field
Acquisition.The cost and efficiency of transmission of hardware must be reduced significantly.
Sampling rate when the utility model acquires signal is far below the sample rate of original signal, the storage to sampling apparatus
It is required that further decreasing.Traditional high-speed sampling module is being replaced with the module of compression sampling, changes previous high-speed sampling institute
Bring power consumption is big, required memory space is big, and when transmission is easy the shortcomings that being interfered, and has reached saving memory space, power consumption
The purpose of reducing, is anti-interference, so that the hardware requirement of NMR signal acquisition device further decreases.
Detailed description of the invention
Fig. 1 is that a kind of compressed sensing based NMR signal acquisition device provided by the embodiment of the utility model is
System structural block diagram；
Fig. 2 is signal pre-processing circuit figure provided by the embodiment of the utility model；
Fig. 3 is analog multiplier circuit figure provided by the embodiment of the utility model；
Fig. 4 is the circuit diagram of low-pass filter circuit provided by the embodiment of the utility model；
Fig. 5 is ADC0809 circuit diagram provided by the embodiment of the utility model；
Fig. 6 is subtraction circuit figure provided by the embodiment of the utility model；
Fig. 7 is RS485 circuit diagram provided by the embodiment of the utility model.
Specific embodiment
In order to make the purpose of the utility model, technical solutions and advantages more clearly understood, below in conjunction with attached drawing and implementation
Example, the present invention will be further described in detail.It should be appreciated that specific embodiment described herein is only used to explain
The utility model is not used to limit the utility model.
It is a kind of structural block diagram of compressed sensing based NMR signal acquisition device as shown in Figure 1, specifically includes that
Receiving coil 1, signal pre-processing circuit 2, analog multiplier 3, integrating circuit 4, low speed ADC sample circuit 5, control system
6 and RS485 circuit 7 and subtracter 8 at.
Receiving coil 1 is determined according to the groundwater depth of required detection, and the utility model selects 100m × 100m
Square coil as receive environment in electromagnetic noise coil；Electromagnetic noise in environment is passed by receiving coil 1
It is defeated by the signal pre-processing circuit 2 of rear end, signal pre-processing circuit 2 is made of preamplifier and bandpass filter, and signal is pre-
Processing circuit 2 is to receive receiving coil 1 small, and the electromagnetic signal of wider range is amplified and filtered, so that place
Signal magnitude after reason is suitble to AD sampling, and frequency band is within the scope of required NMR signal；After signal pre-processing circuit 2
Signal, in analog multiplier circuit, signal and control system transmitting pseudo-random sequence simultaneously pass through 8 subtraction of subtracter
The pseudo-random sequence obtained afterwards is multiplied, and achievees the purpose that the frequency spectrum for extending signal.It can guarantee the number that low speed samples in this way
According to not losing information.Signal after analog multiplier is mixed carries out Integral Processing by integrating circuit 4, and integrating circuit is
The cumulative of multiple points is carried out to fuzzy spectrum signal, so that measurement points decline, to achieve the purpose that reduce sampling rate.
The dimensionality reduction projection of integrated circuit 4 treated signal has been realized in signal, so that data volume much lower, completes measurement
The construction of matrix.It is low to the signal progress after dimensionality reduction that low speed AD sample circuit 5 is carried out by the control of control system core again
Speed sampling, sampling rate at this time are far below the Nyquist sample rate of original signal, i.e., only need the ADC of a low speed
Partial data sampling is completed, the power consumption of hardware sampling section and the requirement to device are greatly reduced.It, will after low speed ADC sampling
It samples obtained compressed data and is sent to control system 6, control system 6 passes through RS485 circuit for collected pressure
Contracting data are transferred to PC, and collected compressed sensing based compressed data is reconstructed original signal by PC.
Shown in Figure 2, signal pre-processing circuit is made of preamplifier and bandpass filter, preamplifier portion
It point far calculates using the LT1028 of three low noises and to be composed in series with a LT1028 operational amplifier after amplifier in parallel, it is preceding
The output end for setting amplifier is connected to a bandwidth-limited circuit, band-pass circuit by two LT1028 far calculate amplifier constitute it is low
Bandpass filter composition, cutoff frequency are 3kHz and high-pass filtering composition, cutoff frequency 1kHz, so that the band logical filter of composition
The range of wave device is between 1kHz-3kHz.
Shown in Figure 3, the pseudo-random sequence that analog multiplier 3 emits control system 6 is by subtraction electricity
The pseudo-random sequence that road 8 is needed simultaneously is multiplied with the analog signal of input, mixing is realized in frequency domain, signal is in time domain phase
Multiply, in frequency domain, that is, convolution, by convolution, in the spread spectrum to entire frequency domain of signal.The simulation of the utility model selection multiplies
Musical instruments used in a Buddhist or Taoist mass chip is AD633, and the chip is cheap and meets design requirement.
Shown in Figure 4 since ideal integrating circuit is extremely difficult in actual hardware circuit, the utility model uses
One low-pass filter replaces integrating circuit, and low-pass filter circuit uses two panels AD823 amplifier, pass through resistance and capacitor connects
It connects, constitutes low-pass filter circuit, instead of the function of true integral circuit, low-pass filter circuit is as shown in Figure 4.
By being mixed with after low-pass filtering, signal realizes dimensionality reduction projection, so that data points substantially reduce.AD is adopted at this time
Sample rate substantially reduces, and requires AD sample circuit also very low.Shown in Figure 5, the utility model uses ADC0809 for sampling
Chip, ADC0809 is one 8 analog-digital converters, low in energy consumption, cheap, the low speed sampling after can satisfy dimensionality reduction
It is required that.
6 major function of control system first is that generate pseudo-random sequence so that pseudo-random sequence is after subtraction circuit 8
Mixing is realized in analog multiplier with the analog signal of input；The pseudo-random sequence that control system generates is defeated by pin
Level range out is between 0-3.3V, that is, the logic level that exports is 0 and 1, and the electricity of required pseudo-random sequence
It is flat to should be+1 and -1, so first needing by subtracter, before logic level is input to analog multiplier 3 by level range
It is converted into -1.5-1.8V, so that the logic level of treated pseudo-random sequence is+1 and -1V；The second of control system
A function is that control low speed AD sample circuit is sampled, and the compressed sensing based compressed data that sampling obtains is passed through
For RS485 circuit transmission to PC machine, control system selects the EP2C8Q208C8N of Alteral company, which has power consumption
It is low, the high feature of performance, therefore the utility model uses this chip as control core；Shown in Figure 6, subtraction circuit is by transporting
It puts and is formed with resistance, by changing the voltage value of resistance value and input, output voltage values required for us, subtraction can be obtained
Device circuit is as shown in Figure 6.
Shown in Figure 7, RS485 circuit is that the data in control system are transferred to computer, and circuit is by one
SP485R chip is constituted, which can be embedded directly into RS485 circuit, RXD the and TXD pin point of control system
It is not connected with the RO pin of SP485R circuit and DI pin.Whether Acquisition Circuit transfers data to PC, the height exported by RD
Low level carries out control transmission, and physical circuit is as shown in Figure 7.
The utility model is compressed sensing based NMR signal acquisition device, will by way of compression sampling
The analog signal projection dimensionality reduction of higher-dimension is to low-dimensional, so that required sampling rate substantially reduces, well below original signal institute
The Nyquist sample rate needed, reduce hardware collecting part requirement so that system power dissipation reduce, be conducive to field it is long when
Between data acquisition.
The above is only the preferred embodiment of the utility model only, is not intended to limit the utility model, all at this
Made any modifications, equivalent replacements, and improvements etc., should be included in the utility model within the spirit and principle of utility model
Protection scope within.
Claims (8)
1. a kind of compressed sensing based NMR signal acquisition device, which is characterized in that the device include: receiving coil,
Signal pre-processing circuit, analog multiplier, integrating circuit, low speed ADC sample circuit, control system, RS485 circuit and subtract
Musical instruments used in a Buddhist or Taoist mass, in which: by being transferred to the signal pre-processing circuit of rear end connection after receiving coil reception electromagnetic signal, the signal is pre-
Electromagnetic signal is amplified and is filtered by processing circuit, so that treated, signal magnitude is suitble to AD sampling, locates in advance by signal
Signal after reason circuit is transmitted in analog multiplier connected to it, and an input terminal of the analog multiplier also passes through subtraction
Device is connected to the output end of control system, and after the output end of the analog multiplier is connect with integrating circuit, signal passes through
Control system is transmitted to by low speed ADC sample circuit after integrating circuit, is connected via the output end of control system
RS485 circuit transmission into PC.
2. device as described in claim 1, which is characterized in that the receiving coil uses the square coil of 100m × 100m
As the coil for receiving electromagnetic noise in environment.
3. device as described in claim 1, which is characterized in that the signal pre-processing circuit includes preamplifier and band logical
Filter, preamplifier include the LT1028 of three low noises far calculate after amplifier in parallel with a LT1028 operational amplifier
It is composed in series, the output end of preamplifier is connected to a bandwidth-limited circuit, and band-pass circuit is far put by two LT1028
The low-pass filter composition that big device is constituted, cutoff frequency are that 3kHz and high-pass filtering forms, cutoff frequency 1kHz, so that
The range of the bandpass filter of composition is between 1kHz-3kHz.
4. device as described in claim 1, which is characterized in that the analog multiplier uses AD633 model chip.
5. device as described in claim 1, which is characterized in that the integrating circuit includes using two panels AD823 transport and placing device, is led to
It crosses auxiliary resistance and capacitor is connected in series.
6. device as described in claim 1, which is characterized in that the low speed ADC sample circuit uses the 8 of ADC0809 model
Position analog-digital converter.
7. device as described in claim 1, which is characterized in that the control system selects Alteral company
EP2C8Q208C8N。
8. device as described in claim 1, which is characterized in that the RS485 circuit uses P485R chip, and FPGA control is single
RXD the and TXD pin of first circuit is connected with the RO pin of SP485R circuit and DI pin respectively.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201920293013.0U CN209727812U (en) | 2019-03-08 | 2019-03-08 | A kind of compressed sensing based NMR signal acquisition device |
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| CN201920293013.0U CN209727812U (en) | 2019-03-08 | 2019-03-08 | A kind of compressed sensing based NMR signal acquisition device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112450941A (en) * | 2020-11-11 | 2021-03-09 | 南昌大学 | Electrocardiosignal compression sampling device and method based on random demodulation structure |
-
2019
- 2019-03-08 CN CN201920293013.0U patent/CN209727812U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112450941A (en) * | 2020-11-11 | 2021-03-09 | 南昌大学 | Electrocardiosignal compression sampling device and method based on random demodulation structure |
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