CN112505536A - Weak signal anti-interference measurement method - Google Patents
Weak signal anti-interference measurement method Download PDFInfo
- Publication number
- CN112505536A CN112505536A CN202011269535.0A CN202011269535A CN112505536A CN 112505536 A CN112505536 A CN 112505536A CN 202011269535 A CN202011269535 A CN 202011269535A CN 112505536 A CN112505536 A CN 112505536A
- Authority
- CN
- China
- Prior art keywords
- weak signal
- measurement method
- interference measurement
- signal anti
- circuit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000691 measurement method Methods 0.000 title claims description 13
- 238000001514 detection method Methods 0.000 claims abstract description 27
- 238000000034 method Methods 0.000 claims abstract description 14
- 230000004927 fusion Effects 0.000 claims abstract description 7
- 230000003321 amplification Effects 0.000 claims description 7
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 7
- 238000006243 chemical reaction Methods 0.000 claims description 5
- 230000005540 biological transmission Effects 0.000 claims description 4
- 239000002184 metal Substances 0.000 claims description 4
- 230000003287 optical effect Effects 0.000 claims description 4
- 239000003990 capacitor Substances 0.000 description 4
- 230000007613 environmental effect Effects 0.000 description 4
- 230000001629 suppression Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/327—Testing of circuit interrupters, switches or circuit-breakers
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Amplifiers (AREA)
Abstract
The invention discloses a weak signal anti-interference measuring method, which comprises the following steps: in the state detection process of the primary and secondary fusion switch, the integrated operational amplifier chip parameters adopted by the detection circuit are as follows: the typical value of the offset voltage is 15 mu V (A level), the bias current is 0.4 nA, the offset current is 0.1 nA, the maximum output current is +/-10 mA, and the error generated by the offset voltage is (2 x 15 mu V) ÷ 10V =3 ppm. The integrated operational amplifier adopts the integrated operational amplifier with the offset voltage typical value of 15 mu V (class A), the bias current of 0.4 nA, the offset current of 0.1 nA and the maximum output current of +/-10 mA, the error generated by the offset voltage is about (2 multiplied by 15 mu V)/10V =3 ppm, and the integrated operational amplifier enhances the detection capability, low null shift and low offset of weak signals.
Description
Technical Field
The invention relates to a weak signal anti-interference measurement method, and belongs to the technical field of primary and secondary fusion switch signal acquisition.
Background
The detection of the primary and secondary fusion switch has wide signal range of measurement and high requirement; the range requires 10mV to 5V, the precision in the range is 0.05 percent, and the angular difference is less than 1'; the power frequency AC signal below 100mV is generally called weak signal.
In the weak signal detection process of the primary and secondary fusion switch, noise can cause poor signal detection accuracy, so that the method is of great importance for noise suppression and shielding, the signal is weak and is easily polluted by field noise, and the noise mainly comprises environmental noise, noise generated by circuit components and power frequency noise of a power supply, so that the noise suppression and shielding need to be comprehensively considered.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the method for measuring the weak signal interference resistance is provided to solve the technical problems in the prior art.
The technical scheme adopted by the invention is as follows: a weak signal anti-interference measurement method comprises the following steps: in the state detection process of the primary and secondary fusion switch, the integrated operational amplifier chip parameters adopted by the detection circuit are as follows: the typical value of the offset voltage is 15 mu V (A level), the bias current is 0.4 nA, the offset current is 0.1 nA, the maximum output current is +/-10 mA, and the error generated by the offset voltage is (2 x 15 mu V) ÷ 10V =3 ppm.
Preferably, the above uses an integrated instrumentation amplifier as a symmetric input, the instrumentation amplifier having a high bandwidth of 10 MHz, a low Total Harmonic Distortion (THD) of-110 dB, and a 0.001% settling time (maximum) of 780 ns.
Preferably, the detection circuit adds a bypass capacitor to a circuit connected to the power supply.
Preferably, the detection circuit employs an analog-to-digital converter having a 50Hz notch in analog-to-digital conversion.
Preferably, the digital circuit portion and the analog circuit portion of the detection circuit are grounded, respectively.
Preferably, the detection circuit signal is accessed into the circuit by using a shielding network line.
Preferably, the shielding network wire is a mesh shielding metal wire, and the shielding layers at two ends are connected with the nearest ground in the transmission line.
Preferably, the integrated instrument amplifier is in a programmable amplification structure, and the amplification factor is changed by adjusting the size of the feedback resistor through a programmable switch.
Preferably, the programmable switch is an optical couple switch.
The invention has the beneficial effects that: compared with the prior art, the invention has the following effects:
1) the integrated operational amplifier adopts the integrated operational amplifier with the offset voltage typical value of 15 mu V (class A), the bias current of 0.4 nA, the offset current of 0.1 nA and the maximum output current of +/-10 mA, the error generated by the offset voltage is about (2 multiplied by 15 mu V)/10V =3 ppm, and the integrated operational amplifier enhances the detection capability, low null shift and low bias of weak signals;
2) the invention adopts an instrument amplifier as a symmetrical input end, the high bandwidth of the instrument amplifier is 10 MHz, -the low Total Harmonic Distortion (THD) of 110 dB, and the 0.001% quick establishment time (maximum value) of 780 ns, the detuning drift and the gain drift which can be ensured are respectively 1.2 mu V/° C and 10 ppm/° C (G = 1000), besides the wide input common mode voltage range, the device also has the high common mode rejection capability of 100 dB when the DC is to 20 kHz and G = 1000, and the performance is improved by keeping the high matching of the internal resistance and the amplifier;
3) in the invention, a bypass capacitor is added at the position of connecting a power supply during circuit design, so that the alternating current noise of the power supply is isolated, and the influence of power frequency noise is reduced;
4) the analog-to-digital converter with 50Hz trapped wave is adopted during analog-to-digital conversion so as to filter 50Hz power frequency interference;
5) the digital circuit part and the analog circuit part are grounded respectively, so that the grounding point of the analog circuit is reduced as much as possible, and noise can be effectively isolated by adopting a circling grounding method;
6) the signal access adopts a shielding network wire to access into the circuit, the outer layer of the shielding network wire is a mesh shielding metal wire, shielding layers at two ends in a transmission line are connected with the nearest ground, interference signals are sent into the ground from an input end and an output end, and the influence of environmental noise on the signals is reduced.
Drawings
FIG. 1 is a schematic diagram of the circuit structure of the present invention;
FIG. 2 is a power supply circuit diagram of an integrated operational amplifier;
FIG. 3 is a power supply circuit diagram of an integrated instrumentation amplifier;
fig. 4 is a 5V power supply circuit.
Detailed Description
The invention is further described with reference to the accompanying drawings and specific embodiments.
Example 1: as shown in fig. 1 to 4, a method for measuring weak signal interference resistance includes: in the state detection process of the primary and secondary fusion switch, the integrated operational amplifier chip parameters adopted by the detection circuit are as follows: the typical value of the offset voltage is 15 mu V (class A), the bias current is 0.4 nA, the offset current is 0.1 nA, the maximum output current is +/-10 mA, the error generated by the offset voltage is (2 x 15 mu V) ÷ 10V =3 ppm, and the reason for adopting the integrated operational amplifier is that: in the weak signal detection process, the suppression and shielding of noise are of great importance, and the signal is weak and is easily polluted by field noise, and the noise mainly comprises environmental noise, noise generated by circuit components and power frequency noise of a power supply, so that the suppression and shielding of the noise are comprehensively considered. In the process of weak signal detection, in order to reduce the interference of the integrated operational amplifier to the circuit, a chip close to an ideal operational amplifier is selected. The main parameters require a small input bias current, a small input bias voltage and zero drift, and a large common mode rejection ratio and input resistance. In particular, the current-voltage conversion stage has high requirements on the integrated operational amplifier, and generally requires that the input bias current of the operational amplifier is in a pA level.
Preferably, the integrated instrumentation amplifier is adopted as a symmetrical input end, the instrumentation amplifier has a high bandwidth of 10 MHz, a low Total Harmonic Distortion (THD) of-110 dB, and a 0.001% setup time (maximum value) of 780 ns, the detuning drift and the gain drift can be guaranteed to be 1.2 μ V/° C and 10 ppm/° C (G = 1000), respectively, besides a wide input common mode voltage range, the device also has a high common mode rejection capability of 100 dB when DC reaches 20 kHz and G = 1000, and the performance is improved by keeping the internal resistance to be highly matched with the amplifier, the integrated instrumentation amplifier is in a structure of program control amplification factor, the size of the feedback resistance is adjusted through the program control switch, so that the amplification factor is changed, and the program control switch selects an optical coupler switch. In order to isolate the digital circuit from the analog circuit, the programmable switch adopts an optical couple switch. In order to improve the performance of the instrumentation amplifier, an integrated instrumentation amplifier is selected.
Preferably, the detection circuit adds a bypass capacitor to a circuit connected to the power supply, because: power frequency noise is the dominant noise affecting a circuit and is typically transferred into the circuit by the power supply of the circuit. In order to reduce the influence, a bypass capacitor is added at the position where the power supply is connected during circuit design, and alternating current noise of the power supply is isolated.
Preferably, the detection circuit adopts an analog-to-digital converter with a 50Hz notch during analog-to-digital conversion, so as to filter out 50Hz power frequency interference.
Preferably, the digital circuit part and the analog circuit part of the detection circuit are grounded respectively, so that noise can be effectively isolated by reducing grounding points of the analog circuit as much as possible and simultaneously adopting a circling grounding method.
Preferably, the detection circuit signal is accessed into the circuit by adopting a shielding network line; the shielding network wire is a netted shielding metal wire, the shielding layers at two ends of the transmission line are connected with the nearest ground, interference signals are sent to the ground from the input end and the output end, and the influence of environmental noise on the signals is reduced.
As shown in fig. 1, the measurement circuit includes an input impedance matching circuit, a low-pass filter circuit (AD), and a signal amplification circuit, which are connected in this order.
The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the present invention, and therefore, the scope of the present invention should be determined by the scope of the claims.
Claims (9)
1. A weak signal anti-interference measurement method is characterized in that: the method comprises the following steps: in the state detection process of the primary and secondary fusion switch, the integrated operational amplifier chip parameters adopted by the detection circuit are as follows: the typical value of the offset voltage is 15 mu V, the bias current is 0.4 nA, the offset current is 0.1 nA, the maximum output current is +/-10 mA, and the error generated by the offset voltage is 3 ppm.
2. The weak signal anti-interference measurement method according to claim 1, wherein: with the integrated instrumentation amplifier as a symmetric input, the instrumentation amplifier has a high bandwidth of 10 MHz, a low total harmonic distortion of-110 dB, and a 0.001% settling time of 780 ns.
3. The weak signal anti-interference measurement method according to claim 1, wherein: the detection circuit adds a bypass capacitance at the circuit to which the power supply is connected.
4. The weak signal anti-interference measurement method according to claim 1, wherein: the detection circuit employs an analog-to-digital converter with a 50Hz notch at the time of analog-to-digital conversion.
5. The weak signal anti-interference measurement method according to claim 1, wherein: the digital circuit part and the analog circuit part of the detection circuit are grounded respectively.
6. The weak signal anti-interference measurement method according to claim 1, wherein: the detection circuit signal is accessed into the circuit by adopting a shielding network wire.
7. The weak signal anti-interference measurement method according to claim 5, wherein: the shielding network wire is a netted shielding metal wire, and the shielding layers at two ends of the transmission line are connected with the nearest ground.
8. The weak signal anti-interference measurement method according to claim 2, wherein: the integrated instrument amplifier is in a structure of program control amplification factor, and the size of the feedback resistor is adjusted through the program control switch, so that the amplification factor is changed.
9. The weak signal anti-interference measurement method according to claim 7, wherein: the program control switch selects the optical couple switch.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011269535.0A CN112505536A (en) | 2020-11-13 | 2020-11-13 | Weak signal anti-interference measurement method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011269535.0A CN112505536A (en) | 2020-11-13 | 2020-11-13 | Weak signal anti-interference measurement method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112505536A true CN112505536A (en) | 2021-03-16 |
Family
ID=74957541
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011269535.0A Pending CN112505536A (en) | 2020-11-13 | 2020-11-13 | Weak signal anti-interference measurement method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112505536A (en) |
Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002184470A (en) * | 2000-12-11 | 2002-06-28 | Fuji Electric Co Ltd | Charge/discharge current measuring apparatus |
| US20100308907A1 (en) * | 2009-06-08 | 2010-12-09 | Edan Instruments, Inc. | Type of High-Performance DC Amplification Device for Bioelectrical Signal Collection |
| CN203324439U (en) * | 2013-06-18 | 2013-12-04 | 滁州学院 | Tester of integrated operational amplifier |
| CN103595354A (en) * | 2013-11-06 | 2014-02-19 | 安徽皖仪科技股份有限公司 | Photovoltaic small-signal acquisition and amplification circuit of ultraviolet and visible spectrophotometer |
| CN103604459A (en) * | 2013-11-13 | 2014-02-26 | 苏州天擎电子通讯有限公司 | A detection amplification apparatus which can detect and amplify weak signals of crops |
| CN203660994U (en) * | 2013-12-31 | 2014-06-18 | 四川红华实业有限公司 | Micro-current amplifier |
| CN105914836A (en) * | 2016-05-24 | 2016-08-31 | 北京工业大学 | Charging-type portable pA micro current monitoring system |
| CN109239432A (en) * | 2018-07-26 | 2019-01-18 | 华中科技大学 | A kind of weak current circuit of nitrogen oxide sensor |
| CN109521235A (en) * | 2018-11-27 | 2019-03-26 | 国网江苏省电力有限公司电力科学研究院 | The complete accuracy checking method of one or two fusion switchgears of one kind and system |
| CN109709152A (en) * | 2019-01-30 | 2019-05-03 | 南通大学 | A kind of insulation film measuring system for fA~pA magnitude weak current |
| CN110441682A (en) * | 2019-09-10 | 2019-11-12 | 浙江华电器材检测研究所有限公司 | A kind of one or two fusion switch test systems |
| CN210639247U (en) * | 2019-09-10 | 2020-05-29 | 杭州电子科技大学信息工程学院 | Weak voltage signal detection system based on power isolation |
-
2020
- 2020-11-13 CN CN202011269535.0A patent/CN112505536A/en active Pending
Patent Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002184470A (en) * | 2000-12-11 | 2002-06-28 | Fuji Electric Co Ltd | Charge/discharge current measuring apparatus |
| US20100308907A1 (en) * | 2009-06-08 | 2010-12-09 | Edan Instruments, Inc. | Type of High-Performance DC Amplification Device for Bioelectrical Signal Collection |
| CN203324439U (en) * | 2013-06-18 | 2013-12-04 | 滁州学院 | Tester of integrated operational amplifier |
| CN103595354A (en) * | 2013-11-06 | 2014-02-19 | 安徽皖仪科技股份有限公司 | Photovoltaic small-signal acquisition and amplification circuit of ultraviolet and visible spectrophotometer |
| CN103604459A (en) * | 2013-11-13 | 2014-02-26 | 苏州天擎电子通讯有限公司 | A detection amplification apparatus which can detect and amplify weak signals of crops |
| CN203660994U (en) * | 2013-12-31 | 2014-06-18 | 四川红华实业有限公司 | Micro-current amplifier |
| CN105914836A (en) * | 2016-05-24 | 2016-08-31 | 北京工业大学 | Charging-type portable pA micro current monitoring system |
| CN109239432A (en) * | 2018-07-26 | 2019-01-18 | 华中科技大学 | A kind of weak current circuit of nitrogen oxide sensor |
| CN109521235A (en) * | 2018-11-27 | 2019-03-26 | 国网江苏省电力有限公司电力科学研究院 | The complete accuracy checking method of one or two fusion switchgears of one kind and system |
| CN109709152A (en) * | 2019-01-30 | 2019-05-03 | 南通大学 | A kind of insulation film measuring system for fA~pA magnitude weak current |
| CN110441682A (en) * | 2019-09-10 | 2019-11-12 | 浙江华电器材检测研究所有限公司 | A kind of one or two fusion switch test systems |
| CN210639247U (en) * | 2019-09-10 | 2020-05-29 | 杭州电子科技大学信息工程学院 | Weak voltage signal detection system based on power isolation |
Non-Patent Citations (3)
| Title |
|---|
| 佚名: "AD8251数据手册", pages 1 - 5, Retrieved from the Internet <URL:https://www.analog.com/cn/index.html> * |
| 佚名: "ADA4077-2数据手册", pages 1 - 5, Retrieved from the Internet <URL:https://www.analog.com/cn/index.html> * |
| 张石锐;郑文刚;黄丹枫;赵春江;: "微弱信号检测的前置放大电路设计", 微计算机信息, no. 23, pages 223 - 224 * |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR100508070B1 (en) | Impedance detector circuit, impedance detector and method of impedance detection | |
| CN101399550B (en) | Discrete-time programmable-gain analog-to-digital converter (adc) input circuit and method | |
| US20100308907A1 (en) | Type of High-Performance DC Amplification Device for Bioelectrical Signal Collection | |
| CN108021172A (en) | A kind of high bandwidth input isolation sampling and precision calibration circuit and method | |
| CN102565485A (en) | Preamplifier for digital phosphor oscilloscope | |
| CN106526570B (en) | Spaceborne laser range finder sounding circuit | |
| CN211701987U (en) | Anti-interference signal acquisition circuit | |
| CN109212448B (en) | Self-stabilizing zero circuit | |
| CN112505536A (en) | Weak signal anti-interference measurement method | |
| CN210514514U (en) | Small signal acquisition circuit applied to power distribution terminal | |
| CN111913027A (en) | Voltage detection circuit applied to high voltage and wide frequency of power electronic transformer | |
| CN115407228A (en) | Method for measuring high-frequency power supply rejection ratio of broadband linear voltage regulator | |
| CN111010179B (en) | Signal compensation calibration method and system | |
| CN216350893U (en) | Capacitor voltage transformer | |
| US10156590B1 (en) | Digital multimeter | |
| CN113795739B (en) | Bridge voltage reversal circuit for vacuum gauge and pressure gauge sensor with same | |
| CN112630524A (en) | Low-current signal acquisition processing circuit and acquisition processing method | |
| CN218243488U (en) | Anti-aliasing filter circuit in industrial internet signal acquisition | |
| CN110429565A (en) | A kind of protection circuit of capacitance-voltage-distributing type electronic type voltage transformer | |
| CN217363029U (en) | Signal processing equipment and interference reduction charge amplifier thereof | |
| CN114157134B (en) | Common mode active filter with simplified structure | |
| CN218037249U (en) | Detection circuit for switching power supply | |
| CN113206666B (en) | Beam atomic clock frequency locking device based on laser-induced fluorescence signal | |
| CN110276857A (en) | A kind of processing method and circuit of aero-engine pressure sensor signal | |
| CN216350924U (en) | Voltage sampling conditioning circuit |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20210316 |