CN201251601Y - Weak low frequency instant vibration signal detection circuit based on frequency measurement - Google Patents
Weak low frequency instant vibration signal detection circuit based on frequency measurement Download PDFInfo
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- CN201251601Y CN201251601Y CNU2008200687644U CN200820068764U CN201251601Y CN 201251601 Y CN201251601 Y CN 201251601Y CN U2008200687644 U CNU2008200687644 U CN U2008200687644U CN 200820068764 U CN200820068764 U CN 200820068764U CN 201251601 Y CN201251601 Y CN 201251601Y
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Abstract
A weak low frequency instant vibration signal detection circuit based on frequency measurement can measure the frequency disturbance of converted tracking signal by tracking unknown strong variable frequency signal of variable input, to detect weak low frequency instant disturbance signal from strong variable frequency signal. The weak low frequency instant vibration signal detection circuit comprises a tracking signal generation circuit and a frequency measurement circuit, wherein the tracking signal generation circuit is composed of a power unit, an emitter following unit, an amplifier unit and a tracking signal generation unit, the frequency measurement unit is composed of a power module, a logic control module, a timer, a counter, a memory, a control and data processing moduel and a display unit. The utility model adopts a modularized design, having simple circuit structure, strong program generality, small volume, low cost, high practicality and high reliability.
Description
Technical field
The utility model relates to the weak instantaneous dither signal detection circuit of low frequency, and more particularly it is a kind of instantaneous dither signal detection circuit of weak low frequency based on frequency measurement.
Background technology
Signal jitter is a kind of common phenomena, mainly is divided into randomness shake and deterministic jitter.Analyze shake and adopt methods such as mean value, standard variance, histogram and jitter spectrum usually, can on time domain, frequency domain and modulation domain, analyze and observe shake.Typical time domain measurement instrument is an oscillograph, but ordinary oscilloscope can not be decomposed into shake the independent frequency component, and when the clock period of collection, number was insufficient, measurement result can appear in digital oscilloscope can not reflect real dither cycle situation.The frequency domain measurement instrument mainly contains dynamic signal analyzer (being also referred to as the fft analysis instrument) and sweep frequency type spectrum analyzer, dynamic signal analyzer analysis frequency bandwidth is limited by sampling rate, for time varying signal or single signal, the scanning of sweep frequency type spectrum analyzer and measured signal can't be synchronous.Therefore, these time domains and frequency domain measurement instrument can't realize detecting the instantaneous dither signal of weak low frequency under the strong frequency variation signal background of the unknown.
On the other hand, common frequency measurement is a frequency of measuring certain single signal or certain class signal, be used for from the frequency content of unknown signaling detection signal, for the weak low-frequency excitation in the strong frequency variation signal, because the frequency of the weak low-frequency excitation of the frequency ratio of strong frequency variation signal is much higher, this frequency measurement method commonly used can't detect the dither signal of weak low frequency from the strong frequency variation signal of the unknown.
Frequency measurement is when handling measured signal, and the first step is that signal is carried out digitizing, according to Nyquist criterion, and for accurate recovering signal, usually need be during sampling times over the sampling rate of measured signal frequency.If the measured signal frequency is higher, high sampling rate will increase the difficulty of data transmission, storage and processing, not only reduces real-time, even can not realize sometimes.
Simultaneously in the life, in carrying out high-power high voltage transmission line of electricity earth detection process, danger in view of operation, supervisory personnel and equipment usually can not be near circuits, coupled signal is to checkout equipment from circuit and take the indirect mode of responding to, and this moment, the signal amplitude and the frequency of induction were all shaken.When slightly electric leakage takes place when, only can cause the variation that induced signal is extremely faint, also say the dither signal that only can produce weak low frequency in other words, this detection is very difficult.
Summary of the invention
The utility model purpose is to overcome above-mentioned existing disadvantages of background technology part, and provide a kind of instantaneous dither signal detection circuit of weak low frequency based on frequency measurement, this circuit has not only reduced the dependence to background signal feature priori, and reduced data sampling rate, improve the real-time of data processing, can fine realization have detected the instantaneous dither signal of weak low frequency under the strong frequency variation signal background of the unknown.
The purpose of this utility model reaches by following measure: a kind of instantaneous dither signal detection circuit of weak low frequency based on frequency measurement, it comprises that tracking signal produces circuit and frequency measurement circuit two parts, it is characterized in that tracking signal produces circuit by power supply unit, the emitter following unit, amplifying unit and tracking signal generation unit are formed, emitter following unit wherein, amplifying unit and tracking signal generation unit are in turn connected into sequential circuit, the output terminal of power supply unit respectively with the emitter following unit, amplifying unit links to each other with tracking signal generation unit power input; The output terminal of tracking signal generation unit links to each other with the frequency measurement circuit input end, described frequency measurement circuit is by power module, Logic control module, timer, counter, storer, control and data processing module and display unit are formed, wherein the Logic control module output terminal links to each other with the timer sum counter respectively, timer, storer, control and data processing module and display unit are in turn connected into sequential circuit, the control signal output ends of control and data processing module links to each other with the counter reset interface, the spill over port of counter links to each other respectively with on timer and the Logic control module, power module respectively with Logic control module, timer, counter, storer, the power input of control and data processing module links to each other.
In technique scheme, the signal Synchronization of described tracking signal generation unit and emitter following unit changes, and the tracking signal generation unit is counter U1.
In technique scheme, frequency measurement circuit is the circuit that has adopted the measuring method of statistical average.
1., the utility model constructs a kind of tracking signal according to the characteristics of the strong frequency variation signal of the unknown and analyze strong frequency variation signal a kind of instantaneous dither signal detection circuit of weak low frequency based on frequency measurement of the utility model has following advantage:, tracking signal and the strong frequency variation signal of tested the unknown change synchronously, the instantaneous dither signal that will detect weak low frequency in the unknown strong frequency variation signal thus promptly is converted into the instantaneous dither signal that detects weak low frequency from tracking signal, has reduced and has detected the weak required data sampling rate of the instantaneous dither signal of low frequency.2., circuit design is simple, volume is little, cost is low.Circuit adopts modular design, and power circuit can adopt general module.3., the data volume of storage and processing is little, real-time.The utility model is reducing under the prerequisite that adopts precision owing to analyzing and processing is tracking signal, has reduced and has detected the weak required data sampling rate of the instantaneous dither signal of low frequency, thereby reduced data storage and processing expenditure, has strengthened real-time.4., program design is flexible, highly versatile.The sensitivity of the utility model in order to guarantee to measure, according to the low frequency characteristic of detection signal, each timing time of design timer by the value of Change In Design Δ T, can satisfy the demand that different frequency signals detects, highly versatile about Δ T=10ms.5., long service life, good reliability.The utility model signal Processing and frequency measurement circuit all integrate, and entire circuit is operated under the small-signal state, and is low in energy consumption, reliable and stable.
Description of drawings
Fig. 1 produces the circuit theory diagrams of circuit for tracking signal.
Fig. 2 is the theory diagram of frequency measurement circuit.
Fig. 3 is the tracking signal waveform of signal-processing board output in the embodiment.
Fig. 4 is the result when low frequency ringing signal disturbs a little less than not having in the embodiment.
Result when Fig. 5 disturbs for weak low frequency ringing signal is arranged in the embodiment.
Embodiment
Describe performance of the present utility model in detail below in conjunction with accompanying drawing, but they do not constitute to qualification of the present utility model, only do for example.Simultaneously by illustrating that advantage of the present utility model will become clear more and understanding easily.
A kind of instantaneous dither signal detection circuit of weak low frequency of the utility model based on frequency measurement, it comprises that tracking signal produces circuit and frequency measurement circuit two parts, tracking signal produces circuit and is made up of power supply unit, emitter following unit, amplifying unit and tracking signal generation unit, wherein emitter following unit, amplifying unit and tracking signal generation unit are in turn connected into sequential circuit, the output terminal of power supply unit links to each other with emitter following unit, amplifying unit and tracking signal generation unit power input respectively, for they provide DC voltage, as shown in Figure 1.The output terminal of tracking signal generation unit links to each other with the frequency measurement circuit input end, and frequency measurement circuit is made up of power module, Logic control module, timer, counter, storer, control and data processing module and display unit.Power module links to each other with the power input of Logic control module, timer, counter, storer, control and data processing module respectively, for they provide operating voltage, as shown in Figure 2.Wherein the Logic control module output terminal links to each other with the timer sum counter respectively, be used for control counter startup, stop the startup with timer.Enabling counting device counting and timer timing when tracking signal rises and arrive.Timer, storer, control and data processing module and display unit are in turn connected into sequential circuit, the control signal output ends of control and data processing module links to each other with the counter reset interface, the spill over port of counter links to each other with Logic control module (certain port) with timer respectively, control and data processing module obtain the time by the content of continuous consults memory, be responsible for simultaneously sending reset instruction to counter, guarantee the operate as normal of counter, and in display unit display process result.
The main signal processing flow of the utility model is: level is followed the unit to unknown strong frequency variation signal, amplifying unit is delivered to the tracking signal generation unit through penetrating, and output frequency is strong frequency variation signal frequency integral multiple/one a tracking signal.The producing method of tracking signal has multiple, and tracking signal of the present utility model produces by counter U1.Strong frequency variation signal is through the emitter following unit, enter counter U1 behind the amplifying unit, triggering for generating tracking signal when the every meter of counter is expired certain numerical value, this circuit had both guaranteed that tracking signal followed unknown strong varying signal and change synchronously, the frequency that has guaranteed tracking signal again is integral multiple/one of this strong varying signal frequency, after this tracking signal enters frequency measurement circuit, Logic control module is enabling counting device counting and timer timing when following the tracks of rising edge arrival, when counter overflows, send the timing halt instruction to timer, timer is delivered to memory stores with the time of record after stopping timing, control and data processing module obtain the time value of measurement by the content of continuous consults memory, be responsible for simultaneously sending reset instruction to counter, guarantee the operate as normal of counter, data processing finishes the back in display unit display process result.This frequency measurement circuit is to utilize counter and timer to realize the measurement of frequency.Counter is according to the feature-set count value of the weak low frequency momentary signal of detect, timer is used for each time of recording counter to begin to the time that finishes, and the method that detects each timing time by fixed count value realizes that the average frequency that each counting began to the concluding time measures.Detect demand for different frequency signals, can be according to the count value of actual modification counter, the application of circuit is wide, and applicability is strong.
Its concrete frequency measurement approach is as follows:
Because the improper sensitivity that can reduce frequency measurement of the selection of rolling counters forward value, in order to guarantee frequency measurement sensitivity, low frequency characteristic (tens hertz to the hundreds of hertz) according to detected signal, each timing time of timer should be chosen in about Δ T=10ms, frequency according to the input tracking signal can design suitable count value, supposes that this count value is N.
Suppose that in the working time control and data processing module receive M the timing output from timer, promptly receive the tracking signal in MN cycle altogether, the time series of establishing timer output is { T
1≤ i≤M}, the tracking signal average frequency that then each timing measures when exporting is:
The average frequency of tracking signal is in the whole working time:
So, the average frequency of tracking signal in the relative overall work time, the relative deviation of the average frequency of each Measuring Time section tracking signal is:
By formula (3) as seen, when not having frequency disturbance, since the just interior among a small circle fluctuation of strong frequency variation signal itself, survey frequency f
iWill with the ensemble average frequency f
AvVery approaching, so relative deviation δ
iJust in very little scope, change, but when the instantaneous frequency disturbance occurring, f
iRelative f
AvBig frequency deviation will appear, δ
iTo occur than acute variation.Therefore, by relative deviation δ
iVariation can realize under the strong frequency variation signal background of the unknown, detecting the instantaneous dither signal of low frequency a little less than this
A kind of detection that can also be applied to moving target based on the instantaneous dither signal detection circuit of weak low frequency of frequency measurement of the utility model.In moving target was surveyed, the unknown strong frequency variation signal of receiver module output was delivered to tracking signal and is produced circuit (as shown in Figure 1), handled back output tracking signal and delivered to frequency measurement circuit.For the sensitivity that guarantees to measure, the requirement of each timing time about Δ T=10ms according to timer, the count value of counters design is N=150, with the frequency sampling tracking signal of 1MHz and the output of frequency measurement circuit, and the output of metering circuit be multiply by 1000% amplify to show.The tracking signal that obtains of sampling as shown in Figure 3, no moving target is through the data processed result during the low frequency ringing a little less than producing as shown in Figure 4.As seen from Figure 4, when not having weak low frequency ringing, the output of frequency measurement circuit is more stable, and the relative deviation absolute value is less than 0.06%, and promptly unknown strong frequency variation signal itself fluctuates among a small circle, and aggregation is good.As the moving target process, when having weak low frequency ringing, the result of the output data of frequency measurement circuit as shown in Figure 5.As seen from Figure 5, because the disturbance of target, at the disturbance time period (point of 180-210 correspondence among the figure, the time corresponding section is 7-9s), rapid shake has taken place in the tracking signal frequency, and maximal phase has surpassed 4% to absolute value of the bias, is 70 times that shake when not having weak low frequency ringing approximately.This shows that the designed circuit of the utility model can realize detecting the instantaneous dither signal of weak low frequency effectively under the strong frequency variation signal background of the unknown.
Claims (3)
1, a kind of instantaneous dither signal detection circuit of weak low frequency based on frequency measurement, it comprises that tracking signal produces circuit and frequency measurement circuit two parts, it is characterized in that tracking signal produces circuit and is made up of power supply unit, emitter following unit, amplifying unit and tracking signal generation unit, wherein emitter following unit, amplifying unit and tracking signal generation unit are in turn connected into sequential circuit, and the output terminal of power supply unit links to each other with emitter following unit, amplifying unit and tracking signal generation unit power input respectively; The output terminal of tracking signal generation unit links to each other with the frequency measurement circuit input end, described frequency measurement circuit is by power module, Logic control module, timer, counter, storer, control and data processing module and display unit are formed, wherein the Logic control module output terminal links to each other with the timer sum counter respectively, timer, storer, control and data processing module and display unit are in turn connected into sequential circuit, the control signal output ends of control and data processing module links to each other with the counter reset interface, the spill over port of counter links to each other respectively with on timer and the Logic control module, power module respectively with Logic control module, timer, counter, storer, the power input of control and data processing module links to each other.
2, a kind of instantaneous dither signal detection circuit of weak low frequency based on frequency measurement according to claim 1 is characterized in that the signal Synchronization of described tracking signal generation unit and emitter following unit changes, and the tracking signal generation unit is counter U1.
3, a kind of instantaneous dither signal detection circuit of weak low frequency based on frequency measurement according to claim 1 is characterized in that frequency measurement circuit is the circuit that has adopted the measuring method of statistical average.
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| Application Number | Priority Date | Filing Date | Title |
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| CNU2008200687644U CN201251601Y (en) | 2008-07-25 | 2008-07-25 | Weak low frequency instant vibration signal detection circuit based on frequency measurement |
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| CNU2008200687644U CN201251601Y (en) | 2008-07-25 | 2008-07-25 | Weak low frequency instant vibration signal detection circuit based on frequency measurement |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103760417A (en) * | 2014-01-07 | 2014-04-30 | 杭州电子科技大学 | Simple AC signal phase acquisition circuit with frequency measurement function |
| CN106603043A (en) * | 2017-01-25 | 2017-04-26 | 国网上海市电力公司 | Jittering signal isolator |
| CN109633265A (en) * | 2019-01-14 | 2019-04-16 | 武汉益坤先舰电气有限公司 | A kind of mains frequency method for real-time measurement and system based on voltage magnitude |
-
2008
- 2008-07-25 CN CNU2008200687644U patent/CN201251601Y/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103760417A (en) * | 2014-01-07 | 2014-04-30 | 杭州电子科技大学 | Simple AC signal phase acquisition circuit with frequency measurement function |
| CN106603043A (en) * | 2017-01-25 | 2017-04-26 | 国网上海市电力公司 | Jittering signal isolator |
| CN109633265A (en) * | 2019-01-14 | 2019-04-16 | 武汉益坤先舰电气有限公司 | A kind of mains frequency method for real-time measurement and system based on voltage magnitude |
| CN109633265B (en) * | 2019-01-14 | 2020-12-15 | 武汉益坤先舰电气有限公司 | Power grid frequency real-time measurement method and system based on voltage amplitude |
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| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20090603 Termination date: 20110725 |