CN207717914U - A kind of breakpoint of cable position detecting system based on low voltage pulse reflection method - Google Patents
A kind of breakpoint of cable position detecting system based on low voltage pulse reflection method Download PDFInfo
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- CN207717914U CN207717914U CN201820047871.2U CN201820047871U CN207717914U CN 207717914 U CN207717914 U CN 207717914U CN 201820047871 U CN201820047871 U CN 201820047871U CN 207717914 U CN207717914 U CN 207717914U
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Abstract
The utility model discloses a kind of breakpoint of cable position detecting system based on low voltage pulse reflection method, it includes CPLD controllers, the first pulse emitting units, the second pulse emitting units and signal isolation shaping unit；First pulse emitting units are mainly made of the first nor gate, the second nor gate, first resistor R1, second resistance R2 and capacitance C；Second pulse emitting units are mainly made of rest-set flip-flop and single-pole double throw key switch；The output end of first pulse emitting units is connected with the first input end of data selector, and the output end of the second pulse emitting units is connected with the second input terminal of the data selector；The output end of data selector is connected with the first input/output port of analog switch.The utility model detects advantage more adaptable with that can select the detectable signal with different pulse widths according to detecting distance to realize.
Description
Technical field
The utility model is related to a kind of breakpoint of cable to detect positioning circuit, specifically a kind of cable suitable for longer lines
Positioning circuit is detected, detection maintenance Instrument technology field is belonged to.
Background technology
Communication cable is the main media of information exchange, is played an important role to the reliability of communication system.For standard
The position for really finding communication cabinet fault generation needs to rely on necessary instrument and equipment.Breakpoint of cable positioning device is common inspection
Repair one of instrument.
Mainly there is measuring principle used by breakpoint of cable positioning device：Bridge method, low voltage pulse reflection method and secondary arteries and veins
Rush method.Wherein bridge method is the intelligent detecting method occurred earliest the sixties, it is detected using bridge balance principle, mainly
There are resistance bridge, capacitance bridge etc., it is lower in widely applied several days this technical intelligence degree of computer technology.
Secondary pulse process is to emit low voltage pulse signal to failure cable using the moment of high-voltage pulse breakdown high resistive fault,
With action of low-voltage pulse short trouble waveform testing cable high resistive fault, this is the detection method in more forward position, but circuit structure ratio
It is more complex.
Widely used at present or low voltage pulse reflection method, its basic principle are to emit a low pressure to tested cable
Pulse can reflect a pulse signal when pulse signal encounters fault point, emit pulse by calculating and reflect the round-trip of arteries and veins
Time difference can calculate rough between test point and fault point in conjunction with the wave velocity that pulse is propagated in particular cable
Distance realizes the Primary Location of failure breakpoint.
In low voltage pulse reflection method, transmitting pulse should have suitable pulse width t, if that exomonental arteries and veins
Width t is rushed (to that is to say to have arrived in t time reflected waves and send out more than two-way time of the low voltage electric impulse in tested cable
The test point position of transmitted wave) so transmitted wave will be Chong Die with back wave, it cannot be distinguished out, the intelligent processors such as microcontroller are just
It can not be detected positioning, measurement blind area occur.Such as the pulse width t of transmitted wave is 0.5 μ s, and low voltage pulse signal exists
Spread speed in cable is 160m/ μ s, then measurement blind area is exactly 40m, low voltage pulse signal only needs 0.5 μ s can be
One is run in tested cable, and back wave reaches test point back and forth, and two pulse signals overlap, and test can not obtain knot
Fruit.Therefore in order to improve detection adaptability, the pulse width of transmitting signal should moderately be reduced.And in the prior art, it is usually sharp
The pulse width of pulse generating circuit realized with basic digital module is mostly s grades of μ, it is difficult to adapt to check frequency require it is small
It designing, narrower pulse transmission signals often use the high speed processors such as FPGA to be realized by complicated algorithm in order to obtain, but this
System hardware and software design difficulty is necessarily caused to increase；Therefore the device of low cost and simple circuit structure can be used to provide narrow arteries and veins
Wide direct impulse has larger practical engineering value.
It is well known that, pulse width is narrower, including radio-frequency component it is abundanter, and larger cable run
High-frequency loss can also make the reduction of reflected impulse amplitude, that is to say that reflection signal is excessively lost totally, excessively faint, receiving circuit
It will be unable to carry out reception processing to this reflection signal, thus can not also carry out time difference measurements, and then fault point locating can not be completed.
Thus in the longer detectable signal that pulse width should not be used narrow instead of detection cable length.
In conclusion need in the prior art it is a kind of can according to detection rough range of the on-site cable breakpoint from test point
The breakpoint of cable of detectable signal of (that is to say the rough length of cable or the be detecting distance) selection with different pulse widths is fixed
Position detecting system.
Utility model content
For deficiencies of the prior art, the purpose of this utility model is：There is provided one kind can according to detection away from
From detectable signal of the selection with different pulse widths, to the breakpoint of cable detection and localization system with stronger detection adaptability
System.
To achieve the goals above, the utility model uses technical solution below.
A kind of breakpoint of cable position detecting system based on low voltage pulse reflection method, it is characterised in that：It includes CPLD controls
Device, the first pulse emitting units, the second pulse emitting units and signal isolation shaping unit processed；
The CPLD controllers are mainly made of divider unit, data selector unit sum number device unit；
The signal isolation shaping unit is mainly made of analog switch and operational amplifier；
First pulse emitting units are mainly by the first nor gate, the second nor gate, first resistor R1, second resistance R2
It is formed with capacitance C；First resistor R1 with and second resistance R2 be connected in series with, connection electrical nodes be denoted as electrical nodes A；First resistor R1
The other end be connected with the output end of the frequency divider；The other end of second resistance R2 is grounded；Electrical nodes A is also with capacitance C's
One end is connected, the other end ground connection of capacitance C；The first input end of first nor gate is connected with the output end of frequency divider
It connects, the second input terminal of the first nor gate is connected with electrical nodes A；The first input end of second nor gate and frequency divider
Output end is connected, and the second input terminal of the second nor gate is connected with the output end of first nor gate, the second nor gate
Output end be the first pulse emitting units output end；
Second pulse emitting units are mainly made of rest-set flip-flop and single-pole double throw key switch, RS triggers
Set end is connected with the first fixing end of single-pole double throw key switch, reset terminal and the single-pole double throw key switch of rest-set flip-flop
The second fixing end be connected, the movable end of single-pole double throw key switch ground connection, the set end and reset terminal of rest-set flip-flop with
Positive pole VCC is connected, and the signal output end of rest-set flip-flop is the output end of the second pulse emitting units；
The output end of first pulse emitting units is connected with the first input end of the data selector, and described
The output end of two pulse emitting units is connected with the second input terminal of the data selector；
The output end of the data selector is connected with the first input/output port of analog switch；The analog switch
Second input/output port is connected with the positive input terminal of operational amplifier, and the negative input end of operational amplifier passes through 3rd resistor R3
It is connected with positive pole, the negative input end of operational amplifier is connected to the ground by the 4th resistance R4；
The output end of the operational amplifier stops end with the counting of counter unit and is connected, the data selector
Output end is connected with the counting start end of counter unit；
The common end COM of the analog switch is the test contact jaw of breakpoint of cable positioning circuit；The numerical control of analog switch
Selection end is connected with the delivery outlet of microcontroller；The selection end of the data selector is connected with the delivery outlet of microcontroller；
The CPLD controllers are communicated by SPI interface and microcontroller.
Further, the microcontroller is connected with LCD display.
Compared with prior art, the utility model has the following advantages that：First pulse emitting units of the utility model generate
Single pulse signal be narrow pulse signal that pulse width is nanosecond, therefore even if in 40m test scopes short in this way,
Exomonental pulse width t is also far smaller than two-way time of the low voltage electric impulse in tested cable, does not appear in the t times
Reflected waves have arrived at the test point position for sending out transmitted wave, and transmitted wave is Chong Die with back wave, cannot be distinguished, lead to not survey
The defect of pulse two-way time in the cable is calculated, in conclusion the utility model has and avoids the short distance measurement blind area from occurring
Advantage.
It can be believed according to the control that microcontroller is sent in addition, the data selector in CPLD controllers is arranged in the utility model
Data selection is carried out number between the first pulse emitting units output signal and the second pulse emitting units output signal, will be selected
Consequential signal is sent to tested cable and carries out thinking that measurement of correlation, the pulse for the detectable signal that the second impulse ejection circuit is exported are wide
Degree wants wide compared to the detectable signal of the first pulse emitting units output, more suitable for longer detection range.
In conclusion in other words the utility model can be according to detection rough range of the on-site cable breakpoint from test point
Detectable signal of (that is to say the rough length of cable or the be detecting distance) selection with different pulse widths, to realize detection
Advantage more adaptable (detecting distance of various length can have more accurate testing result).
Description of the drawings
Fig. 1 is the utility model circuit structure diagram；
Compare shaping unit circuit structure diagram in the utility model of the positions Fig. 2；
Specific implementation mode
The utility model is described in further detail with reference to the accompanying drawings and detailed description.
One, the utility model particular circuit configurations
As shown in Figure 1, a kind of breakpoint of cable position detecting system based on low voltage pulse reflection method of the utility model, it by
CPLD controllers, impulse ejection circuit and signal isolation shaping unit composition.
CPLD controllers can (such as MAX3000) using the common low side CPLD chips that ALTERA companies provide.
First pulse emitting units constitute primary element by integrated nor gate chip, two resistance and a capacitance.Second
Pulse emitting units are then mainly made of rest-set flip-flop.
Signal isolation shaping unit is mainly made of analog switch and operational amplifier.
1, CPLD controllers
It is mainly made of divider unit, data selector unit and counter unit, wherein counter unit has one
A counting start end and a counting stop end (must also have counter output, clock end and clear terminal etc. conventional certainly
Port), counter can be started after the rising edge for including in pulse signal and counted by counting start end and receiving, and counted and stopped
Termination can suspend counting after receiving the rising edge for including in pulse signal, can specifically pass through VHDL hardware description languages
Edge check is realized with decision logic programming, but physical circuit will be converted to by eda tool by programming the counter module realized
Counter structure is finally cured in CPLD chips by netlist；Divider unit and data selector unit then may be used existing
Some schematic diagram unit modules call, but either use VHDL or schematic diagram mode, finally all can be in eda tool
Conversion under form particular circuit configurations.
2, impulse ejection circuit
Impulse ejection circuit includes the first pulse emitting units and the second pulse emitting units
First pulse emitting units：
Mainly it is made of the first nor gate, the second nor gate, first resistor R1, second resistance R2 and capacitance C；First electricity
Resistance R1 with and second resistance R2 be connected in series with, connect electrical nodes be denoted as electrical nodes A；The other end of first resistor R1 and frequency divider
Output end is connected；The other end of second resistance R2 is grounded；Electrical nodes A is also connected with one end of capacitance C, and capacitance C's is another
End ground connection；The first input end of first nor gate is connected with the output end of frequency divider, the second input terminal of the first nor gate with
Electrical nodes A is connected；The first input end of second nor gate is connected with the output end of frequency divider, and the second of the second nor gate is defeated
Enter end with the output end of the first nor gate to be connected, the output end of the second nor gate is the output end of pulse emitting units；Wherein,
The resistance value of first resistor R1 is 1M Ω, and the resistance value of second resistance R2 is 10 Ω, and the capacitance of capacitance C is 1nF or 10nF.
Second pulse emitting units：
It includes rest-set flip-flop and single-pole double throw key switch.The set end of rest-set flip-flop and single-pole double throw key switch
First fixing end is connected, and the reset terminal of rest-set flip-flop is connected with the second fixing end of single-pole double throw key switch, and hilted broadsword is double
The movable end ground connection of key switch is thrown, the set end and reset terminal of rest-set flip-flop are connected with positive pole VCC, rest-set flip-flop
Signal output end be the second pulse emitting units output end.Rest-set flip-flop may be used 74LS29 types and integrate rest-set flip-flop core
Piece realizes that 74LS29 types integrate the middle scale digital integrated circuit that rest-set flip-flop chip is a maturation, and inside is containing there are two RS
Igniter module, each rest-set flip-flop module tool there are one set end (setting 1 end), a reset terminal (setting to 0 end), one
Signal output end and a signal export opposite ends.
But in fact, realize that another more flexible scheme of rest-set flip-flop is：The schematic diagram designed using CPLD
Method of calling is realized, that is to say and rest-set flip-flop is arranged in CPLD controllers.
3, signal isolation shaping unit
As shown in Figure 1, mainly by analog switch and comparing shaping unit and forming, two component parts are all made of conventional die
Realization, such as analog switch may be used common ADG719 alternatives analog switch and (that is to say that " single-pole double throw " is simulated
Switch) it realizes, compare shaping unit and is realized using conventional operational amplifiers.As shown in Fig. 2, the negative input end of operational amplifier is logical
3rd resistor R3 to be crossed with positive pole to be connected, the negative input end of operational amplifier is connected to the ground by the 4th resistance R4,
It is to form a comparator circuit, the threshold value compared is since the ratio of 3rd resistor R3 and the 4th resistance R4 determine, this routine
The prior art, herein not reinflated narration.
4, circuit connecting relation
The output end of first pulse emitting units is connected with the first input end of the data selector, the second pulse hair
The output end for penetrating unit is connected with the second input terminal of the data selector；
The output end of data selector is connected with the first input/output port of analog switch；Second input of analog switch
Delivery outlet is connected with the positive input terminal of operational amplifier；
The output end of operational amplifier stops end with the counting of counter unit and is connected, and the output end of data selector is also
It is connected with the counting start end of counter unit；
The common end COM of analog switch is the test contact jaw of breakpoint of cable positioning circuit；The numerical control of analog switch selects
End is connected with the delivery outlet of microcontroller；The selection end of data selector is connected with the delivery outlet of microcontroller；
CPLD controllers are communicated by SPI interface and microcontroller, and microcontroller is connected with LCD display.
Two, utility model works principle
1, impulse ejection circuit operation principle
First pulse emitting units operation principle：
By the elaboration of background technology it is found that in order to obtain higher detection accuracy, pulse must be generated by reducing check frequency
The narrower detectable signal of width (single pulse signal), the first pulse emitting units in the utility model are to complete above-mentioned work(
Can, generate narrower single pulse signal.Its concrete operating principle is as follows：The frequency divider being arranged inside CPLD controllers is by crystal oscillator
The output signal of clock circuit is divided to obtain frequency square-wave signal appropriate (for example frequency is 1KHZ), is loaded into the first arteries and veins
It rushes on transmitter unit；(high level can maintain 0.001 second) electricity section when the square-wave signal of frequency divider output is between high period
Point A will also be in high level, and (resistance value of second resistance R2 is very big, therefore can will be close to frequency divider with the voltage value of electrical nodes A
Output end voltage value can charge during this certainly to capacitance C), at the same according to the logic feature of nor gate it is found that first or
Non- goalkeeper exports low level, and the second nor gate will also export low level；But when the square-wave signal of frequency divider output is from high level
It is reduced to low level moment, since the resistance value of first resistor R1 is much larger than the resistance value of second resistance R2, capacitance C will pass through
First resistor R1 electric discharges (in this discharge process, electrical nodes A is reduced to low level from high level), while it is noted that
What the output end signal clock of frequency divider was kept during this capacitance C is low level, as a result it will be appreciated that：When frequency divider exports
For low level, and when electrical nodes A is high level, the output of the first nor gate is low level, and the output of the second nor gate is necessarily height
Level (input of the second nor gate two is all low level, takes or is low level afterwards, then negated, is just high level)；Work as frequency divider
Output be low level, and electrical nodes A be low level when, it is clear that the output of the second nor gate be low level.To sum up, in capacitance C
In discharge process, the second nor gate that is to say that the output end of the first pulse emitting units will necessarily be reduced to low electricity from high level
It is flat, there is a positive pulse, and the width of this pulse is the discharge time of capacitance C, is readily apparent that, discharge time
It is the product of the resistance value and the capacitance of capacitance C of second resistance R2, such as the resistance value of second resistance R2 is 10 Ω, the appearance of capacitance C
Value is 1nF, then discharge time is 10ns, the capacitance of capacitance C is 10nF, then discharge time is 100ns.Therefore this reality
With the first novel pulse emitting units can the easily very narrow single pulse signal of output pulse width, this may be one certainly
Not enough regular rectangular pulse, as needed we can also carry out Shape correction to it, it is therefore desirable to be handled, by signal
Regularization, operational amplifier have acted as the effect of this signal instructionsization processing, and common method still utilizes operation amplifier
Device sets operational amplifier to a comparator, and irregular first pulse emitting units output signal is by operational amplifier
Positive input terminal enter, the negative input end voltage of operational amplifier is comparison reference voltage the first pulse emitting units output signal
Voltage is more than the part of reference voltage through comparing output high level, otherwise output low level, operational amplifier export a rule
Digital pulse signal, can similar means be used to obtain the pulse signal of rule in many fields of measurement, be not belonging to the present invention
Improvements, which is not described herein again, considers whether to add a comparison shaping circuit in a word depending on actual test situation, certainly
This transmitting signal is to want rule for reflection signal.
The principle illustrated by background technology is it is found that pulse narrow in this way can overcome two pulses of transmitted wave and back wave
The technical issues of signal overlap causes measurement blind area to occur together.It is further to note that above-mentioned single pulse signal can the period
Property persistently occur because the signal being loaded on the first pulse emitting units is a periodic signal, but this period be 0.002
Second, this is much larger than two-way time of the pulse signal in tested cable, therefore can carry out repeated multiple times detection, to repeatedly detecting
Result of calculation, which carries out data processing, can improve detection accuracy.
Second pulse emitting units operation principle：
Single-pole double throw key switch in second pulse emitting units is a kind of hilted broadsword with flexible keypad work characteristics
Commutator, movable end and the second fixing end are steadily contacted when not pressed, and movable end and the first fixing end are steady after being pressed
Fixed contact, movable end is returned to again after release is steadily contacted with the second fixing end.Therefore when single-pole double throw key switch not by
The level that the set end of rest-set flip-flop obtains when pressing is high level, and the level that the reset terminal of rest-set flip-flop obtains is low level
(set end and reset terminal of rest-set flip-flop are using low level as useful signal), at this point, the signal output end output of rest-set flip-flop
Low level, after single-pole double throw key switch is pressed, it is clear that rest-set flip-flop signal output end export high level, and with
It movable end after unclamping and is returned to again and disappear with the steady contact of the second fixing end, the high level of the signal output end output of rest-set flip-flop
It loses, therefore, to sum up, single-pole double throw toggle switch is pushed once, and the signal output end of rest-set flip-flop sends out a single arteries and veins
Punching, which is the rectangular pulse of a comparison rule.
2, the utility model circuit overall work principle and process
The single pulse signal that either the first pulse emitting units or the second pulse emitting units generate is a kind of low
Press signal, by microcontroller give the selector that is arranged inside CPLD controllers send selection signal just can according to detecting distance into
Row selection, the low pressure pulse that injected pulse radiating circuit generates into tested cable.Such as when detecting distance only has tens of rice
If remote, then microcontroller sends low level selection signal to data selector, by the output signal of the first pulse emitting units
It selects, if conversely, detecting distance is more than 100 meters, then to data selector transmission high level selection signal.
One can be reflected when the direct impulse signal being selected encounters impedance mismatch point (i.e. cable terminal or breakpoint)
A pulse signal (it is an irregular pulse signal certainly), above-mentioned irregular pulse signal is acquired by processor,
The two-way time that the irregular pulse signal of transmitting pulse and reflection can be calculated is poor, in conjunction with pulse in particular cable
The wave velocity of middle propagation can calculate the cable length between impedance mismatch point and test point.Also cable can be found out to open
Fault point locating is realized from the distance between test point in road fault point.To sum up, the measuring principle of the utility model can be summarized as：
Emit a pulse, receive the pulse of reflection, the time difference T between transmitting pulse and reflected impulse is calculated, then T/2
It is that pulse is transmitted to cable terminal or open end required time in tested cable by test point.It will be apparent that
In conjunction with the wave velocity that pulse is propagated in particular cable, the cable that can be calculated between impedance mismatch point and test point is long
Degree is completed to measure.
The single pulse that impulse ejection circuit generates is transmitted to the first input/output port IO1 of analog switch, when numerical control is selected
It selects (low level is sent by the IO of microcontroller) when occurring low level on end, common end COM1 and the first input/output port IO1 connect
It is logical, between two ends can with transmission of analogue signal, meanwhile, cut off between common end COM and the second input/output port IO2, cannot
Transmit signal, at this time impulse ejection circuit generate single pulse just can be transmitted to analog switch common end COM (and electricity
The test contact jaw of cable breakpoint detection circuit).The utility model by it is specifically used when, will test contact jaw consolidated with tested cable
Electrical connection, therefore the single pulse that impulse ejection circuit generates just can be injected into tested cable, and in tested cable
It propagates.When this single pulse signal (referred to as emitting pulse) encounters impedance mismatch point (i.e. cable terminal or open end)
When can reflect an irregular pulse signal (it is also referred to as reflected impulse here).
The utility model by it is specifically used when, test contact jaw and tested cable are consolidated and are electrically connected, therefore reflected impulse
Also will be entered in the utility model circuit by testing contact jaw, it is high when occurring on the numerical control of analog switch selection end SEL at this time
When level, common end COM is connected to the second input/output port, between two ends can with transmission of analogue signal, meanwhile, common end
Cut off between COM and the second input/output port IO2, signal cannot be transmitted, it is clear that at this point, reflected impulse through analog switch second
Input/output port IO2 enters the positive input terminal of operational amplifier.High level on the numerical control selection end SEL of certain analog switch
Or needing the IO by microcontroller to be sent at once after transmitting pulse is sent out, (usual pulse two-way time is in tens to hundreds of nanoseconds
Between, it is therefore necessary to the high level is sent before reflected impulse reaches).
Obviously, the reflected impulse for being sent into operational amplifier is an irregular pulse signal, and microcontroller or CPLD are
It cannot directly handle, it is therefore desirable to be handled, by signal instructions, operational amplifier has acted as this signal instructions
The effect of processing, it is clear that according to aforementioned circuit structure, operational amplifier is arranged to a comparator, random scatters pulse
Entered by the positive input terminal of operational amplifier, the negative input end voltage of operational amplifier is comparison reference voltage, the reference voltage
It is determined by the ratio of 3rd resistor R3 and the 4th resistance R4, the part that transmitting pulse voltage is more than reference voltage is high through comparing output
Level, on the contrary output low level, operational amplifier export a regular digital pulse signal, and this can in many fields of measurement
The pulse signal of rule is obtained using similar means, which is not described herein again.
It is transmitting and the receive process of signal above, the time difference for how obtaining signal transmission is next introduced：Data are selected
The output end for selecting device is connected with the counting start end of counter unit；The output end of operational amplifier and the meter of counter unit
Number stops end and is connected.
While the output end of data selector emits test pulse by analog switch to tested cable, also by the test
The counting start end of counter unit is sent to single pulse (will could carry out signal biography by the IO of CPLD chips certainly
It is defeated), counter starts counting up, the CP pulse signals being counted be CPLD internal works clock (such as common 50MHZ, or
Higher 200MHZ), by taking the work dominant frequency of 200MHZ as an example, corresponding clock cycle t1 is 5ns, that is to say counter with 5ns
Periodic signal be count target start timer counter.0 can be set as by resetting by counting initial value.Realize the another of this function
One scheme is that the output single pulse of impulse ejection circuit is sent to the interrupting input mouth of microcontroller, and interrupting input mouth receives
It is sent to the counter being arranged inside CPLD by interrupt service routine after to interrupt requests and counts enabling signal.In short, real
There are many mode for now starting counting.
When being reflected back a pulse in tested cable, which becomes a rule after being handled via operational amplifier
The counting that digital pulse signal (single pulse) then is sent to counter stops end, and counter stops to preserve after counting
Next current count value, taken as CNT, then being started counting up from timer conter to the time difference T stopped counting
=(CNT-0) × t1, wherein t1 are 5ns.
Obviously, counter start counting up stop count between time difference be that is to say transmitting pulse and reflected impulse it
Between time difference T, then T/2 is pulse cable terminal or open end are transmitted to by test point in tested cable required for
Time.
And the spread speed V of pulse in the cable is then led by the light velocity, the relative dielectric coefficient of cable insulation material and relatively
Magnetic system number determines, usually 160m/ μ s or so.It is to sum up tested cable length S=V × T/2, fault point locating is completed.
Finally illustrate, above example is merely intended for describing the technical solutions of the present application, but not for limiting the present application, although ginseng
The utility model is described in detail according to preferred embodiment, it will be understood by those of ordinary skill in the art that, it can be to this
The technical solution of utility model is modified or replaced equivalently, without departing from the objective and model of technical solutions of the utility model
It encloses, should all cover in the right of the utility model.
Claims (2)
1. a kind of breakpoint of cable position detecting system based on low voltage pulse reflection method, it is characterised in that：It includes CPLD controls
Device, the first pulse emitting units, the second pulse emitting units and signal isolation shaping unit；
The CPLD controllers are mainly made of divider unit, data selector unit sum number device unit；
The signal isolation shaping unit is mainly made of analog switch and operational amplifier；
First pulse emitting units are mainly by the first nor gate, the second nor gate, first resistor R1, second resistance R2 and electricity
Hold C compositions；First resistor R1 with and second resistance R2 be connected in series with, connection electrical nodes be denoted as electrical nodes A；First resistor R1's is another
One end is connected with the output end of the frequency divider；The other end of second resistance R2 is grounded；The one end of electrical nodes A also with capacitance C
It is connected, the other end ground connection of capacitance C；The first input end of first nor gate is connected with the output end of frequency divider, the
Second input terminal of one nor gate is connected with electrical nodes A；The output of the first input end and frequency divider of second nor gate
End is connected, and the second input terminal of the second nor gate is connected with the output end of first nor gate, the second nor gate it is defeated
Outlet is the output end of the first pulse emitting units；
Second pulse emitting units are mainly made of rest-set flip-flop and single-pole double throw key switch, the set end of rest-set flip-flop
It is connected with the first fixing end of single-pole double throw key switch, the reset terminal of rest-set flip-flop and the second of single-pole double throw key switch
Fixing end is connected, the movable end of single-pole double throw key switch ground connection, the set end and reset terminal of rest-set flip-flop with power supply just
Pole VCC is connected, and the signal output end of rest-set flip-flop is the output end of the second pulse emitting units；
The output end of first pulse emitting units is connected with the first input end of the data selector, second arteries and veins
The output end for rushing transmitter unit is connected with the second input terminal of the data selector；
The output end of the data selector is connected with the first input/output port of analog switch；The second of the analog switch
Input/output port is connected with the positive input terminal of operational amplifier, and the negative input end of operational amplifier passes through 3rd resistor R3 and electricity
Source anode is connected, and the negative input end of operational amplifier is connected to the ground by the 4th resistance R4；
The output end of the operational amplifier stops end with the counting of counter unit and is connected, the output of the data selector
End is connected with the counting start end of counter unit；
The common end COM of the analog switch is the test contact jaw of breakpoint of cable positioning circuit；The numerical control of analog switch selects
End is connected with the delivery outlet of microcontroller；The selection end of the data selector is connected with the delivery outlet of microcontroller；
The CPLD controllers are communicated by SPI interface and microcontroller.
2. a kind of breakpoint of cable position detecting system based on low voltage pulse reflection method according to claim 1, feature
It is：The microcontroller is connected with LCD display.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110069027A (en) * | 2019-03-28 | 2019-07-30 | 深圳市联讯通讯技术有限公司 | A kind of cable Measuring error system and its application method with intelligent distributing frame |
| CN112965130A (en) * | 2021-01-25 | 2021-06-15 | 上海磬采电力科技开发有限公司 | Device and method for detecting impurities on surface of wafer |
| CN115331370A (en) * | 2022-07-08 | 2022-11-11 | 深圳市豪恩安全科技有限公司 | Method and device for positioning invasion point of pulse electronic fence |
| CN115598464A (en) * | 2022-10-08 | 2023-01-13 | 金华乐馨发制品有限公司（Cn） | Device and method for detecting and repairing high-voltage and low-voltage circuit at tail end of cable |
-
2018
- 2018-01-11 CN CN201820047871.2U patent/CN207717914U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110069027A (en) * | 2019-03-28 | 2019-07-30 | 深圳市联讯通讯技术有限公司 | A kind of cable Measuring error system and its application method with intelligent distributing frame |
| CN112965130A (en) * | 2021-01-25 | 2021-06-15 | 上海磬采电力科技开发有限公司 | Device and method for detecting impurities on surface of wafer |
| CN115331370A (en) * | 2022-07-08 | 2022-11-11 | 深圳市豪恩安全科技有限公司 | Method and device for positioning invasion point of pulse electronic fence |
| CN115598464A (en) * | 2022-10-08 | 2023-01-13 | 金华乐馨发制品有限公司（Cn） | Device and method for detecting and repairing high-voltage and low-voltage circuit at tail end of cable |
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| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20180810 Termination date: 20190111 |