CN206638771U - A kind of Anti-interference cable fault test system based on TDR - Google Patents
A kind of Anti-interference cable fault test system based on TDR Download PDFInfo
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- CN206638771U CN206638771U CN201720319312.8U CN201720319312U CN206638771U CN 206638771 U CN206638771 U CN 206638771U CN 201720319312 U CN201720319312 U CN 201720319312U CN 206638771 U CN206638771 U CN 206638771U
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Abstract
It the utility model is related to cable fault technical field of measurement and test, more particularly to a kind of Anti-interference cable fault test system based on TDR, it is characterised in that including main control module, pulse generating module, pulse interval measurement module, D/A converter and comparator；The pulse generating module electrically connects with the main control module and tested cable；The comparator includes reference edge, signal input part and compares output end, reference edge of the digital end and analog end of the D/A converter respectively with the main control module and comparator electrically connects, and comparison output end of the pulse interval measurement module respectively with the main control module and comparator electrically connects；The signal input part of the comparator electrically connects with the tested cable；Using the utility model, the multiecho in addition to the first back wave effectively can be efficiently filtered off, so as to the energy automatic identification trouble point without manually on a display screen judging, is easy to make the portable cable fault test system based on TDR.
Description
Technical field
It the utility model is related to cable fault technical field of measurement and test, more particularly to a kind of Anti-interference cable event based on TDR
Hinder test system.
Background technology
Using time domain reflectometry (TDR) by low-voltage high speed pulse-echo, and measure transmitting pulse and failure point reflection arteries and veins
The time difference of punching demarcates position of failure point, and reflected impulse is different with length, the material of circuit, the attenuation degree of reflected impulse
Also different and attenuation amplitude is larger, and this requires to carry out signal enhanced processing to reflected impulse.The method of generally use is to pass through
High-speed a/d gathers waveform to realize trouble spot judging, and not only cost is high for this method, circuit realiration is complicated, and measures accurately
Rate is relatively low, and its first reason is that a cable may pass through multiple impedances such as plug connector, pin joint, pad in wiring process
Change point, when inputting single pulse signal to the cable, obvious reflection is formed (at open circuit or short circuit) in trouble point except crossing
Pulse is outer (in order to be also referred to as the first back wave with echo difference), also echo can be formed in the impedance change point of cable, although its width
Value is smaller than the first back wave, but still forms larger interference when measuring reflection interval；Second reason is the first back wave
Multiple reflections can be produced again and form multiple echoes, and its echo amplitude gradually decays, but is also a kind of interference ripple.Above two
The interference ripple basic characteristics that situation is formed are that amplitude can be smaller than the first back wave, but are difficult to using pulse interval measuring circuit
The first back wave which pulse is really energy representing fault point distance is specified, this just makes measurement result have uncertainty.
Especially in the complicated light current field of some wirings, such as the controlling cable in aircraft, naval vessels, this body length of its cable
Limited, input pulse, the first back wave, various echoes interweave together sometimes, cause substantially to be difficult to work with time domain reflectometry to have
Imitate the localization of faults.
In addition, in order to not damaged to weak electricity system, and the very short cable fault point of length can be differentiated, generally use is low
Voltage burst pulse is as incoming wave, because pulse width is narrow, its reflection wave is complicated, amplitude is changeable, very irregular, and this also gives
Time of measuring brings difficulty, therefore is also required to the pulse so that it becomes more regular.
Certainly, other external interferences are also likely to be present in measuring environment, these interference signals are generally from impulse form, pulse
The low-voltage burst pulse of width etc. and detection cable fault has apparent difference, and is accidental, therefore is to easily determine
With filtering, and above-mentioned echo talker then fundamentally constrain time domain reflectometry in cable fault measuring should
With.Due to the interference of multiecho can not be filtered, therefore it is currently based on TDR and cable fault test system also basic need is passed through
Oscillograph class display device display waveform, the time is then measured by artificial mpving wire, this operation is difficult to realize automatically
Change and judge, and efficiency is low.
Utility model content
The utility model is directed to above-mentioned the deficiencies in the prior art, there is provided one kind being capable of automatic fitration interference echo and accurate
Determine the Anti-interference cable fault test system based on TDR of trouble point.
The technical scheme that the utility model solves above-mentioned technical problem is as follows：A kind of Anti-interference cable failure based on TDR
Test system, it is characterised in that including main control module, pulse generating module, pulse interval measurement module, D/A conversions
Device and comparator；
The pulse generating module electrically connects with the main control module and tested cable；The comparator includes benchmark
End, signal input part and compare output end, the digital end and analog end of the D/A converter respectively with the main control module and
Comparator reference edge electrical connection, the pulse interval measurement module respectively with the main control module and the ratio of comparator
Electrically connected compared with output end；The signal input part of the comparator electrically connects with the tested cable；
The main control module is used for control system work, storing measurement data and preset number amount basic parameter；
The pulse generating module is used to send single pulse signal to tested cable；
The pulse interval measurement module to the output pulse interval by the comparator based on carrying out
Measure and be transferred to main control module；
The D/A converter is used to the digital quantity basic parameter that the main control module provides being converted to analog quantity, gives
The comparator provides benchmark voltage；
The comparator compared with the benchmark voltage, believes the signal input part signal with filtering interference
Number.
Basic functional principle of the present utility model is:The digital quantity benchmark ginseng of stepping is constantly provided using main control module
Number, by being converted to benchmark voltage of the analog quantity as comparator to D/A converter, so that higher than benchmark electricity
The input pulse signal of pressure can not form the output pulse of comparator by comparator less than the benchmark voltage, and lead to
Cross to each benchmark voltage grading to obtain two pulses, i.e. transmitted wave and the first back wave in the comparator output terminal
Pulse, while the first reflected wave pulses of trouble point are detected, multiecho is filtered, so as to be measured using pulse interval
Module metrical pulse transmission time, and then it is scaled trouble point distance.
The beneficial effects of the utility model are：Using the utility model, effectively can efficiently filter off except the first back wave
Outside multiecho, so as to not manually judge on a display screen just energy automatic identification trouble point, further, since comparator is only
Effective shaping has also been carried out by the waveform with benchmark voltage relevant position, therefore to transmitted wave and the first transmitted wave, has been made
It is more accurate to obtain measurement position, based on above-mentioned advantage, the utility model can be made tests system than the existing cable fault based on TDR
The more compact portable test arrangement of system, because existing system must be not easy to minimize by oscillograph artificial screening.
On the basis of above-mentioned technical proposal, the utility model can also do following improvement.
Further, in addition to impedance matching module, the impedance matching module respectively with the tested cable, pulse generation
The output end of module and the signal input part electrical connection of comparator；
The connection impedance that the impedance matching module is used between matching pulse generation module, comparator and tested cable.
Beneficial effect using above-mentioned further scheme is, using impedance matching module, can to make pulse generating module, ratio
Compared with impedance matching is connected between device and tested cable, reduce signal and significantly decay, improve measurement sensitivity.
Utilize the method for testing of Anti-interference cable fault test system of the utility model based on TDR：Including as described above
Anti-interference cable fault test system, testing procedure is as follows：
1) according to tested cable and test request, benchmark voltage A and increment Delta A is selected, starts test；And set ratio
Instant benchmark voltage compared with device is B, makes B=A：
2) a digital quantity basic parameter corresponding with benchmark voltage is exported by main control module to the D/A to turn
Parallel operation, changed by the D/A converter and provide benchmark voltage B to the comparator；
3) pulse generating module produces a single pulse signal to tested cable and comparator；
4) the pulse number N of comparator output is judged by main control module, if N is equal to or less than 1, passes through master control
Molding block reduces benchmark one increment Delta A of voltage, i.e., it is B=B- Δ A to provide benchmark voltage to the comparator, then
Turn such as step 2)；Otherwise it is transferred to step 5)；
5) judge whether the pulse number N of comparator output is equal to 2 again, if it is not, then being reduced by main control module
One increment Delta A of benchmark voltage, i.e., it is B=B- Δs A to provide benchmark voltage to the comparator；Turn again such as step
2)；If equal to 2, then perform step 6)：
6) time between only two pulses is measured by pulse interval measurement module, and then obtains pulse hair
Distance of the exit point to trouble point.
7) measurement terminates.
The beneficial effect of above-mentioned method of testing is：Reasonable selection benchmark voltage A and increment Delta A, can efficiently be sieved
Desired transmitting pulse and the first reflected impulse value are selected, in order to accurately determine the first back wave and transmitted wave time interval,
And then fault distance is determined, it is fast accurate to filter out echo.In filter process., then can be with using comparator shaping useful pulse
Accurate measurement point is selected in recognition, so as to improve measurement accuracy.
Further, the benchmark voltage A is less than transmitting peak value of pulse, and increment Delta A is 2-5 millivolts.
Beneficial effect using above-mentioned further scheme is that, according to the requirement of measurement cable and actual condition, it is reasonable to choose
Increment Delta A, will not be unnecessary two with the umber of pulse for ensureing selected after each benchmark voltage grading.
Further, also using conventional interference filtration step before shown step 1).
Using the prefilter of routine, it is ensured that the accurate implementation of the utility model step.
Further, the D/A converter is 8-12 positions.
8-12 positions can be selected on D/A converter, this depends on the benchmark voltage A and increment Delta A selected,
Such as exomonental theoretical peak is 5 volts, and it is 3 volts that reality output, which can detect peak value, if using increment Delta A to be managed for 3 millivolts
It is differential that 1000 voltages are segmented into by upper 3 volts, then from 10 D/A converters.
So D/A converter can be set according to actual object of measurement and schedule requirement.And then it both can guarantee that each comparison
Reference voltage at most enspheres a pulse after successively decreasing, do not cause to judge confusion, and can selects appropriate increment Δ A to reduce computing time
Number.
Brief description of the drawings
Fig. 1 is a kind of structural representation of Anti-interference cable fault test system of the present utility model；
Fig. 2 is Anti-interference cable fault test system another kind structural representation of the present utility model；
Fig. 3 (a) is the voltage U i principle schematics of comparator input terminal in Fig. 1；
Fig. 3 (b) is the voltage Uo principle schematics of comparator output terminal in Fig. 1；
Fig. 4 is a kind of FB(flow block) of the Anti-interference cable fault testing method based on TDR.
In Fig. 1 to Fig. 4,1, main control module；2nd, pulse generating module；3rd, pulse interval measurement module；4、D/A
Converter；5th, comparator；6th, it is tested cable；7th, impedance matching module.
Embodiment
Principle of the present utility model and feature are described below in conjunction with accompanying drawing, example is served only for explaining this practicality
It is new, it is not intended to limit the scope of the utility model.
As shown in figure 1, a kind of Anti-interference cable fault test system based on TDR, including main control module 1, pulse hair
Raw module 2, pulse interval measurement module 3, D/A converter 4 and comparator 5；Here main control module can use single-chip microcomputer
Deng composition.
The pulse generating module 2 electrically connects with the main control module 1 and tested cable 6；The comparator 5 includes base
Quasi- end, signal input part and compare output end, the digital end and analog end of the D/A converter 4 respectively with the master control molding
The reference edge of block and comparator 5 electrically connect, the pulse interval measurement module 3 respectively with the main control module 1 and ratio
Comparison output end compared with device 5 electrically connects；The signal input part of the comparator 5 electrically connects with the tested cable 6；
The main control module 1 is used for control system work, storing measurement data and preset number amount basic parameter；
The pulse generating module 2 is used to send single pulse signal to tested cable；
The pulse interval measurement module 3 is used for being carried out by the output pulse interval of the comparator 5
Measure and be transferred to main control module；
The D/A converter 4 is used to the digital quantity basic parameter that the main control module provides being converted to analog quantity, gives
The comparator 5 provides benchmark voltage；
The comparator 5 compared with the benchmark voltage, disturbs the signal input part signal to filter
Signal.
Anti-interference cable fault test system another kind structural representation of the present utility model is illustrated in figure 2, itself and Fig. 1
Difference be also to include impedance matching module 7, the impedance matching module 7 respectively with the tested cable 6, pulse generation mould
The output end of block 2 and the signal input part electrical connection of comparator 5；
The impedance matching module 7 is used for the connection that matching pulse occurs between module 2, comparator 5 and tested cable 6 and hindered
It is anti-.
Remaining is repeated no more.
As shown in Figure 3 and Figure 4, to utilize method of testing of the present utility model, here by taking open circuit fault as an example：Including as above
Described Anti-interference cable fault test system, testing procedure are as follows：
1) according to tested cable and test request, benchmark voltage A and increment Delta A is selected, starts test；And set ratio
Instant benchmark voltage compared with device 5 is B, makes B=A：
2) a digital quantity basic parameter corresponding with benchmark voltage is exported to the D/A by main control module 1
Converter 4, changed by the D/A converter 4 and provide benchmark voltage B to the comparator 5；
3) pulse generating module 2 produces a single pulse signal to tested cable 6 and comparator 5；
4) the pulse number N of comparator output is judged by main control module 1, if N is equal to or less than 1, passes through master
Control module 1 reduces benchmark one increment Delta A of voltage, i.e., it is B=B- Δs to provide benchmark voltage to the comparator 5
A, then turn such as step 2)；Otherwise it is transferred to step 5)；
5) judge whether the pulse number N that comparator 5 exports is equal to 2 again, if it is not, then being dropped by main control module 1
Low one increment Delta A of benchmark voltage, i.e., it is B=B- Δs A to provide benchmark voltage to the comparator 5；Turn such as to walk again
It is rapid 2)；If equal to 2, then perform step 6)：
This step has individual premise, is exactly that always amplitude is less and less according to actual ghosts, and the differential of adjacent amplitude is big
So be not in the phenomenon of 3 pulses of final choice in increment Delta A.
6) time between only two pulses is measured by pulse interval measurement module 3, and then obtains pulse
Distance of the launch point to trouble point.
7) measurement terminates.
Fig. 3 (a) is the voltage U i principle schematics of the input of comparator 5 in Fig. 1, it is seen that amplitude highest is transmitting arteries and veins
Punching, it is secondary high for the first back wave, and multiecho then successively decrease by amplitude, it is likely that being returned at by side cable attachment point
Ripple, this echo in time can advanced first back waves.T is time shaft in figure.
Fig. 3 (b) is the voltage Uo principle schematics of the output end of comparator 5 in Fig. 1.Using after above method multiple times of filtration most
Transmitted wave and the first back wave can be obtained eventually, and due to the shaping operation of comparator, its pulse is narrower to more they tend to square wave.Figure
Middle T is time shaft.
In actual process, when comparing, the setting of benchmark voltage is too high, cannot quickly obtain the first reflection arteries and veins
Punching, when setting too low, will occur multiple pulse signals in a cycle and lead to not realize measurement；Therefore in reality
In order to adapt to different test objects and environment in, this requires that benchmark voltage is variable, benchmark voltage A
General choose is less than the transmitting possible peak value of pulse, so can quickly calculate；And increment Delta A selection is will not cause once
Ensphere two pulses after change benchmark voltage is advisable more.
Preferred embodiment of the present utility model is the foregoing is only, it is all in this practicality not to limit the utility model
Within new spirit and principle, any modification, equivalent substitution and improvements made etc., guarantor of the present utility model should be included in
Within the scope of shield.
Claims (2)
1. a kind of Anti-interference cable fault test system based on TDR, it is characterised in that including main control module, pulse generation
Module, pulse interval measurement module, D/A converter and comparator；
The pulse generating module electrically connects with the main control module and tested cable；The comparator includes reference edge, letter
Number input and compare output end, the digital end and analog end of the D/A converter respectively with the main control module and compared with
The reference edge electrical connection of device, the pulse interval measurement module are more defeated with the main control module and comparator respectively
Go out end electrical connection；The signal input part of the comparator electrically connects with the tested cable；
The main control module is used for control system work, storing measurement data and preset number amount basic parameter；
The pulse generating module is used to send single pulse signal to tested cable；
The pulse interval measurement module is used for being measured simultaneously by the output pulse interval of the comparator
It is transferred to main control module；
The D/A converter is used to the digital quantity basic parameter that the main control module provides being converted to analog quantity, to described
Comparator provides benchmark voltage；
The comparator by the signal input part signal compared with the benchmark voltage, to filter interference signal.
2. the Anti-interference cable fault test system according to claim 1 based on TDR, it is characterised in that also include resistance
Anti- matching module, the impedance matching module respectively with the tested cable, the output end of pulse generating module and comparator
Signal input part electrically connects；
The connection impedance that the impedance matching module is used between matching pulse generation module, comparator and tested cable.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720319312.8U CN206638771U (en) | 2017-03-29 | 2017-03-29 | A kind of Anti-interference cable fault test system based on TDR |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720319312.8U CN206638771U (en) | 2017-03-29 | 2017-03-29 | A kind of Anti-interference cable fault test system based on TDR |
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| CN206638771U true CN206638771U (en) | 2017-11-14 |
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| CN201720319312.8U Expired - Fee Related CN206638771U (en) | 2017-03-29 | 2017-03-29 | A kind of Anti-interference cable fault test system based on TDR |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107782234A (en) * | 2017-10-24 | 2018-03-09 | 广州供电局有限公司 | Method for measuring cable length, device and system |
| CN108333476A (en) * | 2018-02-09 | 2018-07-27 | 中国人民解放军海军航空大学 | A kind of cable fault TDR localization methods and system considering cable attenuation characteristic |
-
2017
- 2017-03-29 CN CN201720319312.8U patent/CN206638771U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107782234A (en) * | 2017-10-24 | 2018-03-09 | 广州供电局有限公司 | Method for measuring cable length, device and system |
| CN108333476A (en) * | 2018-02-09 | 2018-07-27 | 中国人民解放军海军航空大学 | A kind of cable fault TDR localization methods and system considering cable attenuation characteristic |
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Granted publication date: 20171114 Termination date: 20200329 |