JP2016014550A - Cable search machine, transmitter and receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set a frequency of a search signal according to a cable of a search object, and easily and accurately perform cable search.SOLUTION: A transmitter 1 includes: an electric length setting unit 11 for setting the electric length of a cable 5 to be a search object; a search signal generation unit 12 for determining a frequency generating resonance in the cable 5 to be a search object on the basis of the set electric length, and generating a search signal of the frequency; and a signal injection unit 13 for injecting the generated search signal to the cable 5 to be a search object. A receiver 2 includes a signal reception unit 21 for receiving a signal from the cable 5 that is a candidate of a search object, and a search signal detection unit 22 for detecting the component of a search signal from the received signal.

Description

  This invention injects a search signal into a cable to be searched, receives a signal from a cable that is a candidate for search, and detects a component of the search signal, thereby identifying the cable to be searched from among the candidates The present invention relates to a cable searcher, a transmitter, and a receiver.

  In a conventional cable searcher, a search signal having a preset frequency is injected from one end side of a cable to be searched, and thereby a signal (electromagnetic wave) generated according to the current flowing through the cable is sent to the other end side or in the middle The search target cable is specified from among the search target candidates (see, for example, Patent Document 1). Here, the search signal used in the cable searcher often uses a signal having a frequency of several kHz to several tens of kHz (see, for example, Non-Patent Document 1).

JP-A-4-9791

Togami Electric Manufacturing Co., Ltd., “Wiring path explorer TLC-C type” catalog

  However, the cable to be searched is often wired in a large building such as a factory or a building, and the cable length is often about several tens of meters. On the other hand, the search signal of the conventional cable searcher is a signal having a relatively low frequency of several kHz to several tens kHz as described above. That is, the wavelength of the search signal is 60 km at 5 kHz and 3 km at 100 kHz, and a signal having a very long wavelength with respect to the cable length is used. When a search signal of such a low frequency is injected, the current flowing through the cable is small, and the reception sensitivity of the cable search machine is low. Therefore, it takes a long time to search, or the wrong cable is selected. There was a problem of ending up.

  The present invention has been made in order to solve the above-described problems. A cable searcher capable of easily and accurately performing a cable search by setting a frequency of a search signal according to a cable to be searched for and a transmission An object is to provide a receiver and a receiver.

  The cable searcher according to the present invention includes a transmitter that is contacted or contactlessly connected to a search target cable, and a receiver that is contacted or contactlessly connected to a search target candidate cable. The transmitter determines an electrical length setting unit that sets the electrical length of the search target cable, and a frequency that causes resonance in the search target cable based on the electrical length set by the electrical length setting unit. A search signal generator for generating a search signal and a signal injection unit for injecting the search signal generated by the search signal generator into a cable to be searched. A signal receiving unit that receives a signal and a search signal detecting unit that detects a component of the search signal from the signal received by the signal receiving unit.

  According to this invention, since it comprised as mentioned above, the frequency of a search signal can be set according to the cable of search object, and a cable search can be performed easily and correctly.

It is a figure which shows the structure of the cable searcher which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the transmitter which concerns on Embodiment 3 of this invention. It is a figure which shows the standing wave of the high frequency signal inject | poured into the cable.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of a cable searcher according to Embodiment 1 of the present invention.
The cable searcher injects a search signal into the cable 5 to be searched, receives a signal from the cable 5 that is the search target candidate, and detects a component of the search signal, thereby detecting the search target component from the candidates. The cable 5 is specified. As shown in FIG. 1, the cable searcher includes a transmitter 1 and a receiver 2. The transmitter 1 and the receiver 2 of this cable searcher are executed by a program process using a CPU based on software.

  The transmitter 1 is connected in contact with or not in contact with the cable 5 to be searched. FIG. 1 shows a case where a signal injection unit 13 (described later) of the transmitter 1 is connected in contact with one end of the cable 5 to be searched. As illustrated in FIG. 1, the transmitter 1 includes an electrical length setting unit 11, a search signal generation unit 12, and a signal injection unit 13.

  The electrical length setting unit 11 sets the electrical length of the search target cable 5. The electrical length setting unit 11 according to the first embodiment receives and sets the electrical length of the cable 5 to be searched from the outside.

  The search signal generator 12 determines a frequency that causes resonance in the cable 5 to be searched based on the electrical length set by the electrical length setting unit 11 and generates a search signal of the frequency.

  The signal injection unit 13 injects the search signal generated by the search signal generation unit 12 into the search target cable 5. FIG. 1 shows a case where a search signal is injected in a contact state from one end of the cable 5 to be searched.

  The receiver 2 is connected in contact with or non-contact with the cable 5 that is a candidate for search. FIG. 1 shows a case where a signal receiving unit 21 (to be described later) of the receiver 2 is connected in a non-contact manner to an intermediate part of the cable 5 that is a candidate for search. As shown in FIG. 1, the receiver 2 includes a signal reception unit 21, a search signal detection unit 22, and a detection result output unit 23.

  The signal receiving unit 21 receives a signal from the cable 5 that is a candidate for search. FIG. 1 shows a case where a signal is received in a non-contact state from a midway portion of the cable 5 that is a candidate for search.

  The search signal detection unit 22 detects a component of the search signal from the signal received by the signal reception unit 21. Here, the search signal detection unit 22 sets information (frequency or the like) related to the search signal according to, for example, an external input, and detects a component of the search signal based on this information.

  The detection result output unit 23 outputs the search result of the search signal by the search signal detection unit 22. The detection result output unit 23 is not an essential component and may be provided outside the cable searcher.

  Here, the electrical length of the cable 5 means an electrical length. That is, the electrical length is equal to the physical length in a vacuum, but when the conductor is covered with an insulator as in the cable 5, the electrical length is longer than the physical length according to the dielectric constant and permeability of the insulator.

Next, a method for searching for the cable 5 by the cable search machine configured as described above will be described with reference to FIG.
When searching for the cable 5, first, the signal injection unit 13 of the transmitter 1 is connected to the cable 5 to be searched. And the electrical length setting part 11 receives the input of electrical length from the outside, and sets the said electrical length as the electrical length of the cable 5 for search. Then, the search signal generator 12 determines a frequency at which resonance occurs in the cable 5 to be searched based on the electrical length (that is, a frequency at which a standing wave is generated and a current flows more strongly in the cable 5). Then, a search signal of the frequency is generated. Then, the signal injection unit 13 injects the search signal into the search target cable 5. Thereby, the search signal propagates through the cable 5 to be searched, and a signal (electromagnetic wave) corresponding to the current flowing through the cable 5 is generated.

Next, the search signal detection unit 22 receives an input from the outside, and sets information (frequency, etc.) regarding the search signal. Further, the signal receiving unit 21 of the receiver 2 is connected to the cable 5 that is a candidate for search. Thereafter, the signal receiving unit 21 receives a signal from the cable 5 that is a candidate for search. Then, the search signal detection unit 22 detects a component of the search signal from the signal received by the signal reception unit 21 based on the information related to the set search signal. Then, the detection result output unit 23 outputs the detection result. At this time, for example, the detection result output unit 23 displays the intensity of the component of the search signal included in the received signal by a numerical value or by displaying the number of lightings using a plurality of LEDs.
From this detection result, the worker determines that the cable 5 that has generated the strongest search signal component signal among the search target candidates 5 is the search target cable 5.

  As described above, according to the first embodiment, the frequency to cause resonance in the cable 5 is determined based on the electrical length of the cable 5 to be searched, and the search signal is generated. The frequency of the search signal can be set in accordance with the characteristics of the cable 5 and the cable 5 can be searched easily and accurately.

  FIG. 1 shows a case where the signal injection unit 13 of the transmitter 1 is connected in contact with one end of the search target cable 5. However, it is not restricted to this, You may connect to the intermediate part of the cable 5, and you may connect non-contact. Similarly, FIG. 1 shows a case where the signal receiving unit 21 of the receiver 2 is connected in a non-contact manner to a midway portion of the cable 5 that is a candidate for search. However, it is not restricted to this, You may connect to the edge part (other end) of the cable 5, and you may make it contact and connect.

Embodiment 2. FIG.
In Embodiment 1, the case where the electrical length of the cable 5 to be searched is input to the electrical length setting unit 11 has been described. On the other hand, the second embodiment shows a case where the electrical length is calculated and set from the physical length of the cable 5 to be searched and the material characteristics of the insulator of the cable itself when the electrical length is unknown.
The basic configuration of the cable searcher according to the second embodiment is the same as that of the cable searcher according to the first embodiment shown in FIG. 1, and only different parts will be described with reference to FIG. .

Here, the electrical length Le of the cable 5 can be expressed by the following expression (1), where L is the physical length of the cable 5.
Le = L × sqrt (εr × μr) [m] (1)

Therefore, if the physical length L of the cable 5 and the relative permittivity εr and relative permeability μr of the transmission medium surrounding the cable 5 are known, the electrical length Le of the cable 5 can be calculated.
On the other hand, the transmission medium surrounding the cable 5 is generally affected by air, walls, other cables 5 and the like in addition to the insulator of the cable 5 itself. However, the dominant transmission medium may be considered as an insulator of the cable 5 itself.

  Therefore, the physical length L of the cable 5 and the relative dielectric constant εr and relative permeability μr of the insulator of the cable 5 itself are input to the electrical length setting unit 11 from the outside. Then, the electrical length setting unit 11 calculates and sets the electrical length of the cable 5 from Equation (1) using the externally input value. In general, since the relative permeability μr≈1, the electrical length may be obtained from only the physical length L and the relative dielectric constant εr.

  In addition, the electrical length setting unit 11 holds in advance a list of insulation candidates for the cable 5 and their relative dielectric constant and relative permeability, and selects and inputs the insulation of the cable 5 from the outside. You may do it.

  As described above, according to the second embodiment, since the electrical length is calculated from the physical length of the cable 5 and the material property of the insulator of the cable 5 itself, in addition to the effects in the first embodiment, A case where the electrical length of the cable 5 to be searched is not known can be handled.

Embodiment 3 FIG.
In the first and second embodiments, the case where the electrical length setting unit 11 sets the electrical length of the search target cable 5 according to the external input has been described. On the other hand, Embodiment 3 shows a case where the electrical length of the cable 5 to be searched is measured and set.
FIG. 2 is a diagram showing the configuration of the transmitter 1 according to Embodiment 3 of the present invention. The transmitter 1 according to Embodiment 3 shown in FIG. 2 is obtained by changing the electrical length setting unit 11 of the transmitter 1 according to Embodiment 1 shown in FIG. 1 to an electrical length setting unit 11b. The rest of the configuration is the same, and only the different parts will be described with the same reference numerals. The configuration of the receiver 2 is the same as that in FIG.

  The electrical length setting unit 11b generates a signal, injects the signal from one end of the search target cable 5 via the signal injection unit 13, and measures the time until the reflected wave of the signal returns. The electrical length of the cable 5 is set. In this case, the signal injection unit 13 of the transmitter 1 is connected to one end of the cable 5 in contact therewith.

Next, a method for searching for the cable 5 by the cable search machine configured as described above will be described with reference to FIG.
When searching for the cable 5, first, the signal injection unit 13 of the transmitter 1 is connected to and connected to one end of the cable 5 to be searched. Then, the electrical length setting unit 11 b generates a signal (for example, a step wave that suddenly changes from one voltage to another voltage) and injects the signal into the search target cable 5 via the signal injection unit 13.

  The step wave injected from one end of the cable 5 propagates through the cable 5 and is reflected at the other end, and the reflected wave propagates in the reverse direction through the cable 5 and returns to the end on the injection side. And the electrical length setting part 11b receives this reflected wave, and measures the time difference from injection | pouring of a step wave to arrival of a reflected wave.

Then, the electrical length setting unit 11b determines that the propagation speed of the signal (electromagnetic wave) in vacuum is c and the time difference from the step wave injection to the arrival time of the reflected wave is Td. The electrical length Le is calculated.
Le = c × (Td / 2) [m] (2)

  Thereafter, the search signal generation unit 12 determines a frequency that causes resonance in the cable 5 to be searched based on the electrical length measured by the electrical length setting unit 11b, and generates a search signal of the frequency. Then, the signal injection unit 13 injects the search signal into the search target cable 5.

  As described above, according to the third embodiment, since the electric length of the cable 5 to be searched is measured and set, in addition to the effects in the first embodiment, a more accurate electric length is obtained. It becomes possible.

Embodiment 4 FIG.
In the first to third embodiments, the search signal generation unit 12 generates a resonance wave in the cable 5 based on the electrical length of the cable 5 to be searched (that is, a standing wave is generated in the cable 5. The frequency at which the current flows more strongly) is selected. Hereinafter, a more specific method for selecting this frequency will be described.

  FIG. 3 is a diagram showing a standing wave of the high frequency signal injected into the cable 5. In FIG. 3, (a) shows a standing wave of a high-frequency signal when one end of the cable 5 is a fixed end and the other end is a free end and the electrical length is Le = λ / 4. The both ends of the cable 5 are fixed ends, and the standing wave of the high-frequency signal when the electrical length is Le = λ / 2 is shown, and (c) shows both ends of the cable 5 are fixed ends, and the electrical length is Le = The standing wave of the high frequency signal in the case of (λ / 2) × 7 is shown. Here, λ is a wavelength corresponding to the frequency of the high frequency signal.

  As shown in FIG. 3, in a standing wave state, a position where the amplitude is 0 without any vibration and a position where the amplitude is maximum and the displacement fluctuates most appear, which are called nodes and antinodes. This node and belly each appear at an interval of λ / 2. The current hardly flows in the node portion, but the current amount becomes maximum in the antinode portion.

When the search signal is injected by connecting the signal injection unit 13 shown in FIGS. 1 and 2 to the fixed end of the cable 5, the frequency Fs of the search signal in which a standing wave stands is determined by the following equations (3) and (4). be able to.
Fs = (c / Le) × n / 2 [Hz] (3)
Fs = (c / Le) × n / 4 [Hz] (4)
Here, Expression (3) shows a case where the end of the cable 5 opposite to the search signal injection side is a fixed end, and Expression (4) shows a case where it is a free end. Basically, equation (4) where Le = (λ / 4) × n may be used so as not to depend on the termination condition (fixed end, free end) of the end portion. Here, the coefficient n is a positive integer.

  As described above, the search signal generation unit 12 can determine the frequency at which a standing wave is generated and a current flows more strongly from the electrical length of the cable 5 and the termination state of the end of the cable 5.

  In addition, when the termination | terminus condition of the edge part on the opposite side to the injection side of the search signal of the cable 5 cannot be confirmed, it can confirm by measuring the electrical length shown in Embodiment 3. In this case, when the polarity of the reflected wave is reversed with respect to the injected signal (negative reflected wave), the end can be determined as a fixed end, and when it is not reversed (positive reflected wave) Can be identified as a free end.

  Further, the coefficient n in the equations (3) and (4) may be arbitrarily set. However, when n = 1 as shown in FIGS. 3 (a) and 3 (b), the position of the belly is one. Since there are only locations, the reception signal of the cable searcher is weak depending on the location, making it difficult to determine. Therefore, for example, according to the position of the receiver 2 of the cable searcher, the coefficient n is set so that an annoyance is always generated within a range in which an operator who searches with the receiver 2 can easily search. Decide the value.

Further, the maximum amount of current is not always obtained at the frequency obtained by the equations (3) and (4). Therefore, before the search is started, the search signals of the frequencies obtained by the equations (3) and (4) and the frequencies before and after the frequency are injected, and the receiver is located at a midpoint where the cable 5 to be searched can be surely seen by visual inspection or the like. 2 may be applied to check the frequency at which the detected signal component becomes maximum.
That is, in this case, first, the search signal generation unit 12 of the transmitter 1 generates a search signal of the determined frequency and frequencies before and after the frequency before performing the search, and searches through the signal injection unit 13. Inject into the target cable 5. Then, the receiver 2 is put on the middle part of the cable 5 to be searched, the signal receiving unit 21 receives a signal from the cable 5, and the search signal detecting unit 22 detects a component of the search signal. Then, the receiver 2 (maximum signal selection unit) selects the frequency of the search signal having the maximum amount of current among the components of the detected search signal. The search signal generation unit 12 of the transmitter 1 generates and uses a search signal corresponding to the selection result by the receiver 2 (maximum signal selection unit) when performing a search.

  In addition, the search signal generator 12 may set the value of the coefficient n not only to an integer but also to a value after the decimal point so that a search signal of a peripheral frequency slightly shifted can be swept and injected. In this case, the amount of current at the antinodes is slightly reduced, but the positions of the nodes and antinodes move with time. Therefore, when a search is performed with the receiver 2 applied to a specific location, a search signal in which the frequency around the determined frequency is swept is generated, and the signal is received for a certain time. A search signal may be detected later.

  As described above, according to the fourth embodiment, the search signal generation unit 12 is configured to determine the frequency from the electrical length of the cable 5 and the termination state of the end of the cable 5, so that the search target The frequency of the search signal can be set according to the cable 5, and the cable 5 can be searched easily and accurately.

  In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

  DESCRIPTION OF SYMBOLS 1 Transmitter, 2 Receiver, 5 Cable, 11, 11b Electrical length setting part, 12 Search signal generation part, 13 Signal injection part, 21 Signal reception part, 22 Search signal detection part, 23 Detection result output part

Claims (9)

A cable searcher comprising: a transmitter connected in contact or non-contact with a cable to be searched; and a receiver connected in contact or non-contact with a cable that is a candidate for search;
The transmitter is
An electrical length setting unit for setting an electrical length of the cable to be searched;
A search signal generating unit for determining a frequency at which resonance occurs in the cable to be searched based on the electrical length set by the electrical length setting unit, and generating a search signal of the frequency;
A signal injection unit for injecting a search signal generated by the search signal generation unit into the search target cable;
The receiver is
A signal receiving unit for receiving a signal from a cable that is a candidate for the search target;
A cable searcher, comprising: a search signal detection unit that detects a component of the search signal from a signal received by the signal reception unit. The transmitter is connected in contact with one end of the cable to be searched,
The electrical length setting unit generates a signal, injects the signal from one end of the search target cable via the signal injection unit, and measures the time until the reflected wave of the signal returns. The cable searcher according to claim 1, wherein the electrical length is set. The cable searcher according to claim 1, wherein the electrical length setting unit sets the electrical length based on a physical length of the cable to be searched and a relative dielectric constant of an insulator of the cable itself. . The search signal generator is configured to search for a frequency Fs = (c / Le) × n / 4, where Le is the electrical length, c is the transmission speed of the search signal in vacuum, and n is a coefficient. The cable searcher according to claim 1, wherein the frequency is determined by a signal frequency. The cable searcher according to claim 4, wherein the search signal generator selects a value of the coefficient n based on a length of a range that can be easily searched by the receiver. The search signal generator generates a search signal of the determined frequency and a frequency before and after the frequency before performing a search,
The receiver is connected in contact or non-contact with the cable to be searched before performing a search,
A maximum signal selection unit that selects the frequency of the search signal that maximizes the amount of current among the components of the search signal detected before performing the search by the search signal detection unit;
The cable searcher according to claim 4, wherein the search signal generation unit generates the search signal corresponding to a selection result by the maximum signal selection unit when performing a search. The cable searcher according to claim 5 or 6, wherein the search signal generation unit generates a search signal obtained by sweeping a frequency around the determined frequency. A transmitter connected in contact or non-contact with a cable to be searched;
An electrical length setting unit for setting an electrical length of the cable to be searched;
A search signal generating unit for determining a frequency at which resonance occurs in the cable to be searched based on the electrical length set by the electrical length setting unit, and generating a search signal of the frequency;
And a signal injection unit for injecting the search signal generated by the search signal generation unit into the search target cable. A receiver connected in contact or non-contact with a cable that is a candidate for search,
A signal receiving unit for receiving a signal from a cable that is a candidate for the search target;
The frequency at which resonance occurs in the cable is determined based on the electrical length set in the transmitter connected in contact or non-contact with the cable to be searched, and the frequency of the frequency that is generated and injected into the cable is determined. And a search signal detector for detecting a component of a search signal from a signal received by the signal receiver.

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