JPH06174457A - Twisting pitch measuring device for communication cable - Google Patents

Abstract

PURPOSE:To accurately measure the twisting pitch of stranded wires constituting a communication cable. CONSTITUTION:A twisting pitch measuring device is provided with a signal generator 4 feeding a signal to stranded wires 2 constituting a communication cable, a loop coil 12 detecting the magnetic field generated in the stranded wires 2 by the signal fed from the signal generator 4, a moving means 14 moving the loop coil 12 along the stranded wires 2, and a recording means 26 correlating and recording the shift distance of the loop coil 12 by the moving means 14 and the detected output of the magnetic field change caused by the shift of the loop coil 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the twist pitch of a twisted wire which constitutes a communication cable.

[0002]

2. Description of the Related Art Generally, a communication cable used for data communication such as a LAN has a considerably high frequency (100M).
Since it is used up to about Hz), the crosstalk characteristic becomes a problem.
In order to improve this crosstalk characteristic, the twist pitch of each twisted wire that makes up the communication cable should be as short as possible, and
It is important to twist the twisting pitch of each twisted wire so that it is different for each twisted wire.

In order to manufacture such a communication cable, it is necessary to inspect whether or not the twisted wires twisted together have a desired twist pitch.

Conventionally, the twist pitch is measured by pressing a scale or the like along the twisted wire, and in this state, the length L of several to several tens of pitches (for example, m pitches) is visually measured, From this value, the length p (= L / m) for one pitch was calculated on average.

[0005]

However, the conventional twist pitch measuring method has a problem that the reading error is large and the value of the length p for one pitch becomes inaccurate.

That is, since the twisted wires are continuously twisted, it is difficult to determine which part corresponds to m pitches, and the average length of one pitch is required.
Even when p is obtained, the measurement results still vary. Further, when the length L for m pitches has a fractional part below the decimal point, even if a scale with a fine scale is used, such a fractional part cannot be read and an error is likely to occur.

The present invention has been made to solve the above problems, and an object of the present invention is to make it possible to more accurately measure the twist pitch of twisted wires constituting a communication cable as compared with the prior art.

[0008]

Therefore, in the twist pitch measuring apparatus for a communication cable according to the present invention, a signal generator for supplying a signal to a twisted wire constituting the communication cable, and a signal supplied from this signal generator. Loop coil for detecting the magnetic field generated in the twisted wire by the moving means, moving means for moving the loop coil along the twisted wire, moving distance of the loop coil by the moving means, and magnetic field change accompanying movement of the loop coil. And a recording unit that records the detection output of the above in association with each other.

[0009]

In the above structure, when the loop coil is moved along the twisted wire by the moving means in the state where the signal is supplied to the twisted wire of the communication cable by the signal generator, the magnetic field of the magnetic field is changed because the twisted wires are twisted together. As the state changes, the magnetic field change is detected by the loop coil. The recording means records the detected output and the moving distance of the loop coil by the moving means in association with each other.

As a result, in the detection output recorded in the recording means, the nodes of the ridges and valleys are very clear, and between the valleys and valleys adjacent to each other, or between the ridges and mountains. Can be obtained extremely accurately as the length for one pitch.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of a twist pitch measuring device for a communication cable according to the present invention.

In the figure, reference numeral 1 indicates the entire twist pitch measuring device, and 2 indicates a twisted wire (twisted wire in this example) that constitutes a communication cable. It has an insulating coating so that it does not short-circuit each other.

Reference numeral 4 is a signal generator for supplying a signal having a predetermined frequency to the twisted wire 2, and 6 is a transformer for impedance matching, the primary side coil of which is connected to the signal generator 4 via a coaxial cable 8. ing. Also, one end of the twisted pair wire 2 is connected to the secondary coil of the transformer 6, and the other ends are connected to each other via a terminating resistor 10.

Reference numeral 12 is a loop coil for detecting the magnetic field generated in the twisted pair wire 2 by the signal supplied from the signal generator 4, and 14 is a moving means for moving the loop coil 12 along the twisted pair wire 2. The moving means 14 includes a moving table 20 to which a part of the coaxial cable 18 connected to the loop coil 12 is fixed, and a pulse motor 22 that drives the moving table 20.

Reference numeral 24 is a selection level meter for measuring the strength of the magnetic field detected by the loop coil 12, and 26 is a movement distance of the loop coil 12 moved by the moving means 14 and a selection level according to the movement of the loop coil 12. A recorder as recording means for recording the magnetic field strengths detected by the total 24 in association with each other, and 28 is a controller for synchronously controlling each movement of the pulse motor 22 and the recorder 26.

When the twist pitch of the twisted pair wire 2 which constitutes the communication cable is measured by using the twist pitch measuring device 1 having the above-mentioned configuration, the signal of the predetermined frequency from the signal generator 4 is fed to the coaxial cable 8 and the transformer. It is supplied to the twisted pair wire 2 via 6.

In this state, the controller 28 gives a control pulse to the pulse motor 22 to drive the movable table 20,
The loop coil 12 is moved along the longitudinal direction of the twisted pair wire 12. In this case, since the strands of the twisted pair wire 2 are twisted together, the state of the magnetic field changes, so that the strength of the magnetic field is detected by the loop coil 12. The detection output of the loop coil 12 is measured by the selection level meter 24 as a change in voltage level. This selection level 2
The measurement signal of No. 4 is given to the recorder 26 at the next stage.

Since the controller 28 controls the movements of the pulse motor 22 and the recorder 26 in synchronization with each other, the recorder 26 is controlled by the selection level meter 24 to change the voltage level.
(Y-axis direction) and the moving distance of the loop coil 12 (X-axis direction) are recorded in association with each other.

That is, as shown in FIG. 2, the strands of the twisted pair wire 2 are twisted together (see FIG.
(a)), the strength of the magnetic field detected by the loop coil 12 is such that peaks and valleys alternate, and each node between the peaks and valleys appears extremely clearly (Fig. 2 (b)). ). Then, the distance p between the valleys adjacent to each other or the distance between the peaks is one pitch length p.

Therefore, for example, the length L for the number of valleys to several tens of pitches (for example, m pitches) is measured, and the length p (= L / m) for one pitch is calculated as an average value from the measured value. Then, the length p for one pitch can be measured extremely accurately.

Particularly, when the twist pitch of the twisted pair wire 12 is small, the twist pitch can be measured by enlarging the moving amount of the loop coil 12 by the pulse motor 22 (enlarging the X axis direction) and recording it in the recorder 26. Will be even easier.

In this embodiment, the case where the twist pitch of the twisted pair wire 2 which constitutes the communication cable is measured has been described. In the case of the quad twisted wire, one pair of strands among them is as described above. Similarly, the twist pitch can be measured. Furthermore, in this example, the stranded wire is taken out from the cable for measurement, but it is not always necessary to take out, and for example, a cable without a shielding material such as Al or Cu tape can be measured even in a completed state. Is.

[0023]

According to the present invention, the twist pitch of the twisted wires forming the communication cable can be measured more accurately than before.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a twist pitch measuring device for a communication cable according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing measurement results obtained by the device of FIG.

[Explanation of symbols]

1 ... Communication cable twist pitch measuring device, 2 ... Twisted wire, 4 ...
Signal generator, 12 ... Loop coil, 14 ... Moving means, 2
6 ... Recording means (recorder).

Claims (1)

[Claims] 1. A signal generator for supplying a signal to a twisted wire constituting a communication cable, a loop coil for detecting a magnetic field generated in the twisted wire by a signal supplied from the signal generator, and the loop coil. A moving means for moving along the twisted wire, and a recording means for recording the moving distance of the loop coil by the moving means and the detection output of the magnetic field change accompanying the movement of the loop coil in association with each other. Characteristic communication cable twist pitch measuring device.