CN204744165U - Biological impedance measurement system based on frequency domain broadband signal - Google Patents
Biological impedance measurement system based on frequency domain broadband signal Download PDFInfo
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- CN204744165U CN204744165U CN201520393115.1U CN201520393115U CN204744165U CN 204744165 U CN204744165 U CN 204744165U CN 201520393115 U CN201520393115 U CN 201520393115U CN 204744165 U CN204744165 U CN 204744165U
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Abstract
The utility model belongs to the technical field of biological impedance is measured, a biological impedance measurement system based on frequency domain broadband signal is specifically disclosed. This system including be used for controlling this system biological tissue measuring CPU the control unit, with FPGA processing unit that CPU the control unit connects, with digital analog conversion unit that FPGA processing unit connects, with the signal amplification unit of digital analog conversion unit connection and with the biological impedance measuring electrode array of signal amplification unit connection. Simultaneously the utility model discloses a parallel demodulation operation is done in that FPGA is inside simultaneously to the binary channels of gathering biological tissue's the input and output signals that awaits measuring respectively, makes the test system can once generate several range and phase informations frequently, and it is hundredfold so not only how many to have improved with the measuring speed, but also has improved the frequency resolution.
Description
Technical field
This utility model belongs to biological impedance technical field, especially relates to a kind of bio-impedance testing system based on frequency domain broadband signal.
Background technology
Biological impedance is that a kind of electrical characteristics of biological tissue and organ and Changing Pattern thereof of utilizing extracts the detection technique with Human Physiology, pathological condition relevant information, the feature such as have noinvasive, harmless, cheap, simple to operate and function information enriches.When carrying out biological impedance, according to the frequency characteristic of biological tissue to be measured, need the sinusoidal tone signal launching different frequency, often send out a single-tone sinusoidal signal, measure amplitude under this frequency of biological tissue and phase place, need, through repeatedly repeated measure, just can obtain required width and respond mutually.When needs frequency accuracy is higher, the synthesis that often once complete frequency domain measurement needs hundreds of thousands of single-tones to measure, this can cause speed slowly.Such as: choose 100 frequencies in 1KHz ~ 2MHz, by digital frequency synthesizer bill tone signal, often send a single-tone, measure once amplitude and the phase place of this tone signal.100 frequencies need measurement just can complete the scanning of full frequency band for 100 times.Therefore, this existing method generally comes with some shortcomings: 1) speed slowly: in actual scene, and tester holds probe, and judges probe and the contact situation of biological tissue, keeps a period of time with to be measured complete after contact is good; If the time that measurement device needs tester to keep is greater than 1 second, the Limb shaking of tester just can affect test result, and traditional method data acquisition time added signal processing time, much larger than 1 second; 2) frequency resolution is low: frequency resolution is higher, can embody the frequency response details of biological tissue, can be more accurate when doing the data fitting of algorithm, and higher frequency resolution needs more frequency, and system speed will be lower.
And another kind of method adopts digital to analog converter to send pulse signal, because pulse signal can reflect the information of whole frequency domain after discrete Fourier transform (DFT).But the signal to noise ratio that this method exists single frequency point is very low, and its time domain waveform is pulse, pulse signal to circuit dynamically and response time requirement very high, therefore the method prior art generally less.
Utility model content
For the deficiency that above-mentioned prior art exists, the purpose of this utility model is to provide a kind of quick sampling and the high bio-impedance testing system based on frequency domain broadband signal of resolution.
To achieve these goals, the technical scheme that adopts of this utility model is as follows:
Based on a bio-impedance testing system for frequency domain broadband signal, this system comprises
CPU control unit, for controlling the measuring biological tissue of this system;
FPGA processing unit, is connected with described CPU control unit;
D/A conversion unit, is connected with described FPGA processing unit, mutually changes for digital signal and analogue signal being realized;
Signal amplification unit, is connected with described D/A conversion unit, for analogue signal being amplified;
Biological impedance electrod-array, is connected with described signal amplification unit, for encouraging and gather the bioimpedance signal of biological tissue.
Preferably, described FPGA processing unit comprises signal synthesizing module, the FIR shaping filter module be connected with described signal synthesizing module, FIR narrow-band filtering module and the discrete Fourier transform module with described FIR narrow-band filtering model calling.
Preferably, described digital-to-analogue conversion form unit comprises over-sampling D/A converter module, over-sampling analog-to-digital conversion module I and over-sampling analog-to-digital conversion module II, wherein said over-sampling D/A converter module and described FIR shaping filter model calling, described over-sampling analog-to-digital conversion module I and described over-sampling analog-to-digital conversion module II respectively all with described FIR narrow-band filtering model calling.
Further, described signal amplification unit comprises AFE (analog front end) driver module, AFE (analog front end) amplification module I and AFE (analog front end) amplification module II, wherein said AFE (analog front end) driver module is connected with described over-sampling D/A converter module, described AFE (analog front end) amplification module I is connected with described over-sampling analog-to-digital conversion module I, and described AFE (analog front end) amplification module II is connected with described over-sampling analog-to-digital conversion module II.
Further, described biological impedance electrod-array is primarily of four biological impedance electrodes circumferentially array distribution formation, and described biological impedance electrode is connected with described AFE (analog front end) driver module, described AFE (analog front end) amplification module I and described AFE (analog front end) amplification module II respectively.
After adopting said structure, the advantage that this utility model is compared to the prior art had is as follows: this utility model adopts the dual pathways gathering the input/output signal of biological tissue to be measured respectively, do parallel demodulation computing in FPGA inside simultaneously, make test macro once can generate amplitude and the phase information of several thousand frequencies, not only measuring speed is improve hundred times simultaneously, but also improve frequency resolution.
Accompanying drawing explanation
Below in conjunction with drawings and Examples, this utility model is further illustrated:
Fig. 1 is the structural representation of bio-impedance testing system described in this utility model embodiment.
Reference numeral:
10-CPU control unit; 20-FPGA processing unit, 21-signal synthesizing module, 22-FIR shaping filter module, 23-FIR narrow-band filtering module, 24-discrete Fourier transform module; 30-D/A conversion unit, 31-over-sampling D/A converter module, 32-over-sampling analog-to-digital conversion module I, 33-over-sampling analog-to-digital conversion module II; 40-signal amplification unit, 41-AFE (analog front end) driver module, 42-AFE (analog front end) amplification module I, 43-AFE (analog front end) amplification module II; 50-biological impedance electrod-array, 51-biological impedance electrode.
Detailed description of the invention
The following stated is only preferred embodiment of the present utility model, does not therefore limit protection domain of the present utility model.
As shown in Figure 1, this utility model embodiment provides a kind of bio-impedance testing system based on frequency domain broadband signal, and this system comprises
CPU control unit 10, for controlling the measuring biological tissue of this system;
FPGA processing unit 20, is connected with described CPU control unit 10;
D/A conversion unit 30, is connected with described FPGA processing unit 20, mutually changes for digital signal and analogue signal being realized;
Signal amplification unit 40, is connected with described D/A conversion unit 30, for analogue signal being amplified;
Biological impedance electrod-array 50, is connected with described signal amplification unit 40, for encouraging and gather the bioimpedance signal of biological tissue.
Wherein, the described FPGA processing unit 20 discrete Fourier transform module 24 that comprises signal synthesizing module 21, the FIR shaping filter module 22 be connected with described signal synthesizing module 21, FIR narrow-band filtering module 23 and be connected with described FIR narrow-band filtering module 23.
Described digital-to-analogue conversion form unit 30 comprises over-sampling D/A converter module 31, over-sampling analog-to-digital conversion module I 32 and over-sampling analog-to-digital conversion module II 33, wherein said over-sampling D/A converter module 31 is connected with described FIR shaping filter module 22, and described over-sampling analog-to-digital conversion module I 32 and described over-sampling analog-to-digital conversion module II 33 are all connected with described FIR narrow-band filtering module 23 respectively.
Described signal amplification unit 40 comprises AFE (analog front end) driver module 41, AFE (analog front end) amplification module I 42 and AFE (analog front end) amplification module II 43, wherein said AFE (analog front end) driver module 41 is connected with described over-sampling D/A converter module 31, described AFE (analog front end) amplification module I 42 is connected with described over-sampling analog-to-digital conversion module I 32, and described AFE (analog front end) amplification module II 43 is connected with described over-sampling analog-to-digital conversion module II 33.
Described biological impedance electrod-array 50 is primarily of four biological impedance electrodes 51 circumferentially array distribution formation, and described biological impedance electrode 51 is connected with described AFE (analog front end) driver module 41, described AFE (analog front end) amplification module I 42 and described AFE (analog front end) amplification module II 43 respectively.
By this, bio-impedance testing system described in this utility model embodiment adopts the two acquisition channels gathering the input/output signal of biological tissue to be measured respectively, and the pumping signal collected and acquired signal are done parallel demodulation computing in FPGA processing unit inside simultaneously, often send out compared to existing technology a single-tone sinusoidal signal measure biological tissue under this frequency amplitude with phase place and the amplitude-frequency response that just can obtain required frequency domain after repeatedly repeated measure compare, this systematic sampling speed promotes one times.
For those of ordinary skill in the art can better understand technical scheme described in above-described embodiment, the concrete measuring method of bio-impedance testing system described in the utility model is as follows:
Step one: choose different frequency f (1), f (2) ... time-domain signal synthesized wideband signal x (t) of f (n), wherein n=1,2,3 ... N; T represents the sampling number of discrete time signal, and in this utility model embodiment, t gets 1 ~ 8192.The frequency domain broadband signal that this utility model embodiment is obtained in 3KHz ~ 2MHz by time history synthesis filtering, and this broadband signal represents by the filtered frequency-region signal of shaping filter, contains all frequencies of required frequency range.The digital filter of excitation shaping filter is different, and the waveform of its frequency Out-of-band rejection is also different.
Step 2: the broadband signal x (t) of synthesis is constantly circulated after shaping filter and is sent to D/A conversion unit, so that continuing to implement to encourage to the biological impedance electrode with contact biological tissue measures, after user stops impedance detection, stop sending broadband signal.
Step 3: the pumping signal and the acquired signal that are simultaneously gathered biological tissue to be measured by biological impedance electrode.Described broadband signal x (t) will through signal processing and amplifying before implementing to encourage to the biological impedance electrode with contact biological tissue, and to improve the signal to noise ratio of system, result is more accurate.
Step 4: pumping signal and acquired signal are carried out parallel demodulation and processed after signal amplification and analog digital conversion in FPGA, obtains biological tissue's amplitude-frequency characteristic value.Wherein, the concrete steps of described parallel demodulation are: the excited data obtained after analog digital conversion and image data are carried out narrow-band filtering process; And then the amplitude and phase information with multiple frequency is once generated through discrete Fourier transform.
In this utility model embodiment, adopt high-speed digital-analog conversion and analog digital conversion, and do FIR filtering to realize promoting sampling signal to noise ratio at numeric field.And this utility model embodiment adopts the frequency domain broadband signal in frequency domain 3KHz ~ 2MHz, time-domain signal is obtained by inverse discrete fourier transform, in FPGA processing unit, realize the FIR shaping filter to broadband signal x (t), and start to apply to encourage to the biological impedance electrode with contact biological tissue after the digital-to-analogue conversion of high speed over-sampling is analogue signal; Adopt high speed over-sampling analog digital conversion to improve system signal noise ratio at signals collecting receive path simultaneously, be used in after doing discrete Fourier transform (DFT) in FPGA processing unit and obtain the high biological tissue's amplitude-frequency characteristic of frequency resolution.
In addition, this utility model is that one-shot measurement covers all frequencies, and FPGA receiving terminal once generates amplitude and the phase information of several thousand frequencies by discrete Fourier transform (DFT).Technical solutions of the utility model make frequency resolution and speed only have relation with the scale of FPGA, the maximum ability that can reach one-shot measurement 4096 frequencies, much larger than traditional method, sampling rate promotes hundreds of times to frequency resolution (frequency resolution can be less than 500Hz).
Foregoing is only preferred embodiment of the present utility model, for those of ordinary skill in the art, according to thought of the present utility model, all will change in specific embodiments and applications, this description should not be construed as restriction of the present utility model.
Claims (5)
1., based on a bio-impedance testing system for frequency domain broadband signal, this system comprises
CPU control unit (10), for controlling the measuring biological tissue of this system;
FPGA processing unit (20), is connected with described CPU control unit (10);
D/A conversion unit (30), is connected with described FPGA processing unit (20), mutually changes for digital signal and analogue signal being realized;
Signal amplification unit (40), is connected with described D/A conversion unit (30), for analogue signal being amplified;
Biological impedance electrod-array (50), is connected with described signal amplification unit (40), for encouraging and gather the bioimpedance signal of biological tissue.
2. the bio-impedance testing system based on frequency domain broadband signal according to claim 1, it is characterized in that, the discrete Fourier transform module (24) that described FPGA processing unit (20) comprises signal synthesizing module (21), the FIR shaping filter module (22) be connected with described signal synthesizing module (21), FIR narrow-band filtering module (23) and is connected with described FIR narrow-band filtering module (23).
3. the bio-impedance testing system based on frequency domain broadband signal according to claim 2, it is characterized in that, described digital-to-analogue conversion form unit (30) comprises over-sampling D/A converter module (31), over-sampling analog-to-digital conversion module I (32) and over-sampling analog-to-digital conversion module II (33), wherein said over-sampling D/A converter module (31) is connected with described FIR shaping filter module (22), described over-sampling analog-to-digital conversion module I (32) is all connected with described FIR narrow-band filtering module (23) respectively with described over-sampling analog-to-digital conversion module II (33).
4. the bio-impedance testing system based on frequency domain broadband signal according to claim 3, it is characterized in that, described signal amplification unit (40) comprises AFE (analog front end) driver module (41), AFE (analog front end) amplification module I (42) and AFE (analog front end) amplification module II (43), wherein said AFE (analog front end) driver module (41) is connected with described over-sampling D/A converter module (31), described AFE (analog front end) amplification module I (42) is connected with described over-sampling analog-to-digital conversion module I (32), described AFE (analog front end) amplification module II (43) is connected with described over-sampling analog-to-digital conversion module II (33).
5. the bio-impedance testing system based on frequency domain broadband signal according to claim 4, it is characterized in that, described biological impedance electrod-array (50) is primarily of four biological impedance electrodes (51) circumferentially array distribution formation, and described biological impedance electrode (51) is connected with described AFE (analog front end) driver module (41), described AFE (analog front end) amplification module I (42) and described AFE (analog front end) amplification module II (43) respectively.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105769194A (en) * | 2016-03-30 | 2016-07-20 | 缤刻普锐(北京)科技有限责任公司 | Device for quickly measuring human body information |
| CN106264525A (en) * | 2015-06-09 | 2017-01-04 | 思澜科技（成都）有限公司 | Bio-impedance testing system based on frequency domain broadband signal and method thereof |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106264525A (en) * | 2015-06-09 | 2017-01-04 | 思澜科技（成都）有限公司 | Bio-impedance testing system based on frequency domain broadband signal and method thereof |
| CN105769194A (en) * | 2016-03-30 | 2016-07-20 | 缤刻普锐(北京)科技有限责任公司 | Device for quickly measuring human body information |
| CN105769194B (en) * | 2016-03-30 | 2018-11-13 | 缤刻普锐(北京)科技有限责任公司 | A kind of device of quick measurement human body information |
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