CN110345887A - A kind of length of mesh wire measurement method based on the adaptive range of TDR technology - Google Patents
A kind of length of mesh wire measurement method based on the adaptive range of TDR technology Download PDFInfo
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- CN110345887A CN110345887A CN201910013895.5A CN201910013895A CN110345887A CN 110345887 A CN110345887 A CN 110345887A CN 201910013895 A CN201910013895 A CN 201910013895A CN 110345887 A CN110345887 A CN 110345887A
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- length
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B15/00—Measuring arrangements characterised by the use of electromagnetic waves or particle radiation, e.g. by the use of microwaves, X-rays, gamma rays or electrons
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
Abstract
The present invention discloses a kind of length of mesh wire measurement method based on the adaptive range of TDR technology, length of mesh wire measurement method is to issue a burst pulse wave from cable one end, it can be reflected back when this signal reaches cable opposite end, calculate the time for receiving reflected impulse, the transmission speed of burst pulse wave is recycled to arrive the length of cable multiplied by the time for receiving reflected impulse.The present invention can take into account the linear measure longimetry of wider range by using the circulation measurement method of multiple transmitted pulse width grades, can be well solved existing product on the market as only with " big blind area, small-range " problem brought by single transmitted pulse width grade.
Description
Technical field
The present invention discloses a kind of length of mesh wire measurement method, especially a kind of cable based on the adaptive range of TDR technology
Length measurement method belongs to Time Domain Reflectometry (TDR) field of measuring technique.
Background technique
As internet is using more and more extensive, the usage amount of cable is also increasing, for grid line manufacturer
For retailer or engineering construction, need often come into contacts with cable, in addition to it is to be understood that wire rod specification, quality and break-make situation
Outside, it also needs to know the length of cable that it is used sometimes.The simplest mode for measuring length of mesh wire be use tape measure, and
Efficiency is very low in such a way that original tape measure is measured, and interim emergency can be cannot apply in engineering construction, at this moment on a large scale
With regard to needing a electronic product to carry out automatic measurement, to improve working efficiency.
The equipment of the electronic surveying length of mesh wire of early stage is all measured using resistance principle, the hardware of this mode
Cost and software cost are lower, but its maximum drawback is the line resistance for the unit length that user need to know each wire rod type in advance
(i.e. the resistance of the electric wire of unit length) is how many, and need to find the upper receiver of other end connection and just be able to achieve the measurement,
The two is obviously not easy to practical operation；, which also there are many measuring instruments in present market, to be measured using capacitance principle, this
It is exactly to be not necessarily to find the cable other end to can measure that mode, which has its benefit, but by cable material and use environment (temperature, humidity
Deng) influence is very big, and cannot accurately measure location of short circuit point.
Summary of the invention
For cable in the prior art measurement mentioned above, not convenient enough, accurate disadvantage, the present invention provide one kind
Based on the length of mesh wire measurement method of the adaptive range of TDR technology, TDR technology is used, using between transmitted wave and back wave
Time difference, the shortcomings that measuring the length of cable, better solve existing measurement method.
The technical solution used to solve the technical problems of the present invention is that: a kind of cable based on the adaptive range of TDR technology
Length measurement method, the length of mesh wire measurement method are to issue a burst pulse wave from cable one end, when this signal reaches net
It can be reflected back when line opposite end, calculate the time for receiving reflected impulse, recycle the transmission speed of burst pulse wave multiplied by reception
The time of reflected impulse is to get the length for arriving cable.
The technical scheme adopted by the invention to solve the technical problem further comprises:
The burst pulse wave wave period is 20ns~200ns.
The burst pulse wave is the fast edge signal that step source issues.
The length of mesh wire measurement method includes the following steps:
Step S1, emitted using the transmitted wave of pulsewidth grade 1, obtain it after waiting receiving end acquisition to complete signal and adopt
The data of collection；
Step S2, it calculates average value: skipping the transmitted wave part of the transmitted pulse width grade, subsequent waveform is carried out to ask flat
Mean value AVG is used as analysis threshold values；
Step S3, it is compared according to mean value AVG, finds out the rising point TD1, peak point TD2 and drop point TD3 of transmitted wave；
Step S4, default open circuit threshold values multiplying power R, as judging the effective foundation of back wave；
Step S5, compared according to back wave and average value AVG, find out back wave rising point RD1, peak point RD2 and under
Point RD3 drops；
Step S6, the numerical value of the peak point RD2 of back wave and the threshold values of setting are compared, if the former is bigger than the latter, then it is assumed that
The class of emission is effective, obtains total time used in signal transmission back and forth according to (RD1-TD1) at this time, then whether judge this time
Meet the measurement effective range of the class of emission, if meeting report as a result, otherwise resurveying 3 times, if 3 times are all unsuccessfully determined as surveying
Amount failure；If the former is smaller than the latter, then it is assumed that the class of emission is not inconsistent, replace next class of emission jump to step S1 repeat hold
Row, to the last grade failure, then it is assumed that measurement failure shows that this situation is likely to be and there is not wiring or cable beyond measurement
Maximum range, according to the Computing Principle of L=vt, wherein v is electric signal in the spread speed of conductor, and t is propagation time, energy
Enough calculate separately the length for obtaining each cable.
The default open circuit threshold values multiplying power R is 1.25.
The length of mesh wire measurement method further includes step S0, and step S0 includes following sub-step:
Step S0-1, line is measured: carries out the on off test of line sequence, finds out the connection relationship of each core, find out respectively
Two kinds of situations of short circuit and open circuit, break-make situation is recorded, and is prepared to survey long analysis reflection configuration below；
Step S0-2, long environment is surveyed in initialization: obtaining its core number and hardware corridor number and core according to wire rod type
Number corresponding relationship, and open the long control end signal of survey；
Step S0-3, it is transferred to step S1, carries out length computation.
Further include following step after the step S0-1:
Step S0-1 ', according to step S0-1 to line result judgement, respectively to short circuit and open circuit situation carry out length survey
Amount；
If step S0-1 ", line 1 are open-circuit condition, selection line 1 is transmission channel, and line 2 is receiving channel, line 1 and line 2
It is one group of twisted pair, carries out one-to-one differential signal measurement, if line 1 is short-circuit condition, selection line 1 logical for transmitting
Road, the line with its short circuit are that receiving channel carries out linear measure longimetry.
It, can be with the beneficial effects of the present invention are: circulation measurement method of the present invention by using multiple transmitted pulse width grades
The linear measure longimetry for taking into account wider range can be well solved existing product on the market by only with single transmitted pulse width grade institute
Bring " big blind area, small-range " problem.
Below in conjunction with the drawings and specific embodiments, the present invention will be further described.
Detailed description of the invention
Fig. 1 is that TDR of the present invention measures impedance discontinuity schematic diagram.
Fig. 2 is TDR signal mode figure of the present invention.
Fig. 3 is the TDR waveform diagram of present invention actual measurement open circuit situation.
Fig. 4 is the TDR waveform diagram of present invention actual measurement short-circuit conditions.
Fig. 5 is the execution flow chart of the present invention one channel length of cable of measurement.
Fig. 6 is non-differential signal waveform diagram.
Fig. 7 is differential signal waveform schematic diagram.
Specific embodiment
The present embodiment is the preferred embodiment for the present invention, other its all principles and basic structure are identical or close as the present embodiment
As, within that scope of the present invention.
TDR is the abbreviation of English Time Domain Reflectometry, and Chinese name is that measurement passes domain reflectometer
The main tool of defeated line characteristic impedance, TDR are mainly made of three parts: for generating the signal generator of pulse signal, being used for
The signal sampler of signal and the Signal Analysis System for being handled signal are acquired, is become when impedance occurs in transmission path
When changing (i.e. differential-mode impedance is discontinuous), portion of energy can be reflected, and remaining energy will continue to transmit.
In the present invention, the length of mesh wire measurement method based on the adaptive range of TDR technology is mainly tester from cable one
End issues a burst pulse wave (in the present embodiment, burst pulse wave is ns rank, usually 20ns~200ns), when this signal
When reaching cable opposite end, because opposite end open circuit (impedance suddenly becomes infinitely great) will be reflected back, it is anti-that instrument calculates reception
The time of pulse is penetrated, cable is longer, and the time of pulse one back and forth is longer, can calculate the length of cable accordingly.When implementation, by
Fast edge signal (i.e. narrow pulse signal, the pulsewidth 20ns~200ns, amplitude 3.3v that step source (i.e. signal generator) issues
Pulse) be injected on tested transmission line, if transmission line impedance is continuous, this fast edge step signal just along transmission line forward
It propagates, when impedance variations occurs in transmission line, (i.e. opposite end is opened a way, and impedance suddenly becomes infinitely great or another is terminated with and cable electricity
Hinder unmatched resistance, inductance) when, the fast edge signal that step source issues is reflected with regard to some, and a part continues past
Preceding propagate (in the present embodiment, as long as can partially emit the case where the impedance mismatch of cable midway, if it is open circuit situation, is also wrapped
The impedance mismatch of extreme case is included, transmitting signal can be reflected all), step of the reflected Signal averaging to injection
Signal, oscillograph (i.e. signal sampler) can collect this signal.Because reflected signal and the signal of injection have one
The fixed time difference, so the edge of this collected superposed signal of oscillograph is (i.e. transmitting Signal averaging reflection with the level
Signal causes the signal detected to have the phenomenon that step), this step reflects the time relationship of signal propagation reflections, with transmission
Wire length is corresponding.
In the present embodiment, the cable definition for loading burst pulse wave is become into transmission channel, i.e., is actively sent out on transmission channel
A burst pulse wave (ns rank, time t1, the i.e. perdurabgility of burst pulse wave are t1) out, electric signal passes through wire transmission,
Transmitting terminal will be reflected when the impedance discontinuity on line.Elapsed time is recorded as t2 at this time, is existed according to electric signal
The spread speed and propagation time t2 of conductor can calculate the distance (i.e. the length of gauze) that the signal is walked, in order to essence
T2 really is measured, the scheme that FPGA cooperation high-speed ADC is used in the present invention measures, to improve the resolution of measurement
Rate.
It is transmitted back to baud point in wire transmission according to narrow spaces electric wave signal (20ns~200ns), and pulse is being led
Line spread speed (100m/us, i.e. 1m/10ns) it is found that according to 300M sample frequency (i.e. 3.33ns sample an AD value),
Therefore theoretically its resolution ratio is ± 0.33m, so it is with small measurement blind spot, within 33cm, i.e., can be surveyed using the present invention
Amount is greater than the length of mesh wire of 33cm), it is calculated according to most jogging speed 100m/us is propagated, sets and can measure length range 2000m,
Then AD samples the used time: (2000/100) * 2=40us.
In other words, time t2 is 40us, then can calculate length of mesh wire is 2000m.
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.
Specific implementation step of the invention is as follows:
Step S1, line is measured:
Using the sample mode of electric resistance array (when it is implemented, using line sequence commonly used in the prior art and can also lead to
Disconnected test mode) on off test that carries out line sequence, the connection relationship of each core is found out, short circuit is found out respectively and open circuit (does not have
Have short circuit) two kinds of situations, their break-make situation is recorded, is prepared to survey long analysis reflection configuration below；
Step S2, long environment is surveyed in initialization:
The corresponding relationship of its core number and hardware corridor number and core number is obtained according to wire rod type, and opens the long control of survey
End signal processed；
Step S3, length computation, in the present embodiment, step S3 includes following sub-steps:
S300: according to step S1 to line result judgement, measurement of length is carried out to short circuit and open circuit situation respectively；
S301: the characteristics of according to cable, transmission channel and receiving channel are selected；In the present embodiment, by taking twisted pair as an example, if
Line 1 is open-circuit condition (i.e. they are not short-circuit), then selection line 1 is transmission channel, and line 2 is that (line 1 and line 2 are multiple twins to receiving channel
One group of line, line 2 is used as reference signal, i.e. the V- of differential signal) carry out one-to-one differential signal measurement (herein
It is not the differential signal of stricti jurise, please refers to attached drawing 6 and attached drawing 7), if line 1 is short-circuit condition, selection line 1 is transmitting
Channel, the line with its short circuit are that receiving channel carries out linear measure longimetry；
S302: it is different in the reflected energy of same wire length according to the transmitted wave of different in width, therefore sample different arteries and veins
Wide grade principle measures, and using pulsewidth grade 1, (i.e. most narrow spaces grade, in the present embodiment, pulsewidth grade uses 3 first
A pulsewidth grade, is 20ns, 100ns, 200ns respectively, and most narrow spaces described herein refer to the transmitted wave of 20ns) transmitted wave
Emitted, the data of its acquisition are obtained after waiting FPGA acquisition to complete signal, are next transferred to step S303 or step S304
Carry out waveform analysis；
S303: open circuit waveform analysis carries out open circuit waveform analysis if line 1 is open-circuit condition:
A, it calculates its mean value: skipping the transmitted wave part of the class of emission, the AVG that averages is carried out to subsequent waveform,
It is used as analysis threshold values；
B, it is compared according to mean value AVG, the rising point TD1 for finding out transmitted wave (it is identical as average value AVG to emit wave amplitude
When), peak point TD2 and drop point TD3 (when transmitting wave amplitude is identical as average value AVG)；
C, an open circuit threshold values multiplying power R (in the present embodiment, using empirical value 1.25) is preset, as judging that back wave is effective
Foundation；
D, it is compared according to back wave and average value AVG, finds out rising point RD1 (reflex amplitude and the average value of back wave
When AVG is identical), peak point RD2 and drop point RD3 (when reflex amplitude is identical as average value AVG)；
E, (i.e. mean value AVG and threshold values multiplying power R's multiplies for the numerical value of the peak point RD2 of comparison back wave and the threshold values of setting
Product), if the former is bigger than the latter, then it is assumed that the class of emission is effective, and it is used back and forth to obtain signal transmission according to (RD1-TD1) at this time
Total time, then judge (in the present embodiment, in the 1st grade, i.e., whether this time meets the measurement effective range of the class of emission
20ns, because the pulsewidth of transmitting is small, corresponding energy is also small, and it is also small to survey range, theoretically effective measurement range be 5m~
50m, if using the 1st level measurement result in this range if be considered normal, and if it exceeds effective range, such as
Measure 100m, it is evident that violate reality, therefore need to resurvey, the 2nd grade 30-250 meters of measurement range effective, and 3rd level effectively measures
200-950 meters of range, this measurement range can refer to effective measurement distance of TDR technology), inform upper layer as a result, otherwise if meeting
It resurveys 3 times；If the former is smaller than the latter, then it is assumed that the class of emission is not inconsistent, and replaces next class of emission and jumps to step S301 weight
It is multiple to execute, a to the last grade failure, then it is assumed that measurement failure shows that this situation is likely to be and there is not wiring or cable to exceed
Measure maximum range；
S304: it if line 1 and line 2 are short-circuit condition, are identified according to the TDR wave characteristics of short-circuit conditions, is answered at this time
Analysis back wave is carried out in the negative direction of waveform mean value；
S305: the analytic process of short-circuit waveform analysis, this analytic process and S303 open circuit situation is substantially similar, but pre- here
If threshold line in the lower section of mean value line；
According to the Computing Principle of L=vt, wherein v is electric signal in the spread speed of conductor, and t is the propagation time, can be divided
It is not calculated respectively with the length of root cable.
The present invention can take into account the length survey of wider range by using the circulation measurement method of multiple transmitted pulse width grades
Amount can be well solved existing product on the market as only with " big blind area, a small amount of brought by single transmitted pulse width grade
Journey " problem.
Claims (7)
1. a kind of length of mesh wire measurement method based on the adaptive range of TDR technology, it is characterized in that: the length of mesh wire measures
Method is to issue a burst pulse wave from cable one end, can be reflected back when this signal reaches cable opposite end, calculating connects
It receives the time of reflected impulse, the transmission speed of recycling burst pulse wave arrives cable multiplied by the time for receiving reflected impulse
Length.
2. the length of mesh wire measurement method according to claim 1 based on the adaptive range of TDR technology, it is characterized in that: institute
The burst pulse wave wave period stated is 20ns~200ns.
3. the length of mesh wire measurement method according to claim 1 based on the adaptive range of TDR technology, it is characterized in that: institute
The burst pulse wave stated is the fast edge signal that step source issues.
4. the length of mesh wire measurement method according to claim 1 based on the adaptive range of TDR technology, it is characterized in that: institute
The length of mesh wire measurement method stated includes the following steps:
Step S1, emitted using the transmitted wave of pulsewidth grade 1, obtain its acquisition after waiting receiving end acquisition to complete signal
Data；
Step S2, it calculates average value: skipping the transmitted wave part of the transmitted pulse width grade, average to subsequent waveform
AVG is used as analysis threshold values；
Step S3, it is compared according to mean value AVG, finds out the rising point TD1, peak point TD2 and drop point TD3 of transmitted wave；
Step S4, default open circuit threshold values multiplying power R, as judging the effective foundation of back wave；
Step S5, it is compared according to back wave and average value AVG, finds out the rising point RD1, peak point RD2 and drop point of back wave
RD3；
Step S6, the numerical value of the peak point RD2 of back wave and the threshold values of setting are compared, if the former is bigger than the latter, then it is assumed that the hair
It penetrates that grade is effective, signal transmission total time used back and forth is obtained according to (RD1-TD1) at this time, then judge whether this time meets
The measurement effective range of the class of emission, if meeting report as a result, otherwise resurveying 3 times, if being all unsuccessfully judged as 3 times, measurement is lost
It loses；If the former is smaller than the latter, then it is assumed that the class of emission is not inconsistent, and replaces next class of emission and jumps to step S1 and repeats,
To the last grade failure, then it is assumed that measurement failure, show this situation be likely to be do not have wiring or cable beyond measurement most
Wide range, according to the Computing Principle of L=vt, wherein v is electric signal in the spread speed of conductor, and t is propagation time, Neng Goufen
The length of each cable is not calculated.
5. the length of mesh wire measurement method according to claim 4 based on the adaptive range of TDR technology, it is characterized in that: institute
The default open circuit threshold values multiplying power R stated is 1.25.
6. the length of mesh wire measurement method according to claim 4 based on the adaptive range of TDR technology, it is characterized in that: institute
The length of mesh wire measurement method stated further includes step S0, and step S0 includes following sub-step:
Step S0-1, line is measured: carries out the on off test of line sequence, finds out the connection relationship of each core, find out short circuit respectively
With two kinds of situations of open circuit, break-make situation is recorded, is prepared to survey long analysis reflection configuration below；
Step S0-2, long environment is surveyed in initialization: obtaining its core number and hardware corridor number and core number according to wire rod type
Corresponding relationship, and open the long control end signal of survey；
Step S0-3, it is transferred to step S1, carries out length computation.
7. the length of mesh wire measurement method according to claim 6 based on the adaptive range of TDR technology, it is characterized in that: institute
Further include following step after the step S0-1 stated:
Step S0-1 ', according to step S0-1 to line result judgement, respectively to short circuit and open circuit situation carry out measurement of length；
If step S0-1 ", line 1 are open-circuit condition, selection line 1 is transmission channel, and line 2 is receiving channel, and line 1 and line 2 are double
One group of twisted wire, carries out one-to-one differential signal measurement, if line 1 is short-circuit condition, selection line 1 is transmission channel, with it
The line of short circuit is that receiving channel carries out linear measure longimetry.
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