Method and apparatus for testing cables
First Claim
1. In a network comprising a plurality of high speed digital lines connecting a first switch and a second switch, with each switch having a plurality of ports, each of which can be switched to one of the high speed digital lines, an improved test apparatus comprising:
- a) a signal source connected to a port of the first switch;
b) a DC voltage meter connected to a different port of the first switch; and
c) electronic circuitry having an input and an output, wherein an AC signal at the input is converted to a DC signal at the output, and the input is connected to a port of the second switch and the output is connected to a different port of the second switch,wherein the second switch is a far end switch, andwherein the plurality of ports of the second switch are connectable to a plurality of user devices, each user device being selected from the group consisting of a telecommunications device and a personal computer.
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Accused Products
Abstract
Apparatus and method for testing lines. The apparatus is particularly useful for testing lines in a switched network, such as might be used to electronically route telephone and computer data lines to various offices in an office building. The apparatus includes an AC test source and a DC measurement device located at a near end switch. A DC transform circuit is located at a far end switch. According to the test method, an AC test signal is injected onto a line under test at the near end. At the far end, the received signal is converted to DC, which is sent to the near end. Line attenuation, and hence fault conditions, are detected by comparing the DC signal to the transmitted AC signal. Techniques to increase the signal to noise ratio of the DC signal are also disclosed.
16 Citations
17 Claims
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1. In a network comprising a plurality of high speed digital lines connecting a first switch and a second switch, with each switch having a plurality of ports, each of which can be switched to one of the high speed digital lines, an improved test apparatus comprising:
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a) a signal source connected to a port of the first switch; b) a DC voltage meter connected to a different port of the first switch; and c) electronic circuitry having an input and an output, wherein an AC signal at the input is converted to a DC signal at the output, and the input is connected to a port of the second switch and the output is connected to a different port of the second switch, wherein the second switch is a far end switch, and wherein the plurality of ports of the second switch are connectable to a plurality of user devices, each user device being selected from the group consisting of a telecommunications device and a personal computer. - View Dependent Claims (2, 3, 4, 5, 6)
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7. In a network comprising a plurality of lines connecting a first switch and a second switch, with each switch having a plurality of ports, each of which can be switched to one of the lines, an improved test apparatus comprising:
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a) a signal source connected to a port of the first switch; b) a DC voltage meter connected to a different port of the first switch; c) electronic circuitry having an input and an output, wherein an AC signal at the input is converted to a DC signal at the output, and the input is connected to a port of the second switch and the output is connected to a different port of the second switch; and d) a computer programmed to actuate the first switch to connect the signal source to a first one of the plurality of lines and the DC voltage meter to a second one of the plurality of lines and to actuate the second switch to connect the input of the electronic circuitry to the first of the plurality of lines and the output of the electronic circuitry to the second of the plurality of lines.
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8. In a network comprising a plurality of lines connecting a first switch and a second switch, with each switch having a plurality of ports, each of which can be switched to one of the lines, an improved test apparatus comprising:
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a) a signal source connected to a port of the first switch; b) a DC voltage meter connected to a different port of the first switch; and c) electronic circuitry having an input connected to a port of the second switch, an output connected to a different port of the second switch, and a means for producing a DC signal, wherein an AC signal at the input is converted to a DC signal at the output, and wherein the DC signal has a value of a first polarity when the AC signal is above a predetermined threshold and the DC signal has a value with a polarity opposite the first polarity when the AC signal is below a predetermined threshold. - View Dependent Claims (9)
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10. A switched electrical network comprising:
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a) first switch means for connecting one of a plurality of inputs to one of a plurality of high speed digital lines; b) means, connected to the first switch means, for injecting an AC test signal onto one of the plurality of high speed digital lines; c) means, connected to the first switch means, for measuring a DC level on one of the plurality of high speed digital lines; d) second switch means for connecting one of the plurality of high speed digital lines to one of a plurality of device ports; e) DC transform means, having an input connected to one of the plurality of device ports and an output connected to another one of the plurality device ports of the second switch means, for converting an AC signal to a DC value deterministically related to the magnitude of the AC signal, wherein the second switch means is a far end switch, and wherein the plurality of device ports of the second switch means are connectable to a plurality of user devices, each user device being selected from the group consisting of a telecommunications device and a personal computer. - View Dependent Claims (11, 12, 13)
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14. A switched electrical network comprising:
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a) first switch means for connecting one of a plurality of inputs to one of a plurality of lines; b) means, connected to the first switch means, for injecting an AC test signal onto one of the plurality of lines; c) means, connected to the first switch means, for measuring a DC level on one of the plurality of lines; d) second switch means for connecting one of the plurality of lines to one of a plurality of device ports; e) DC transform means, having an input connected to one of the plurality of device ports and an output connected to one of the device ports of the second switch, for converting an AC signal to a DC value deterministically related to the magnitude of the AC signal; and f) means for controlling the network connected to the first switch means and the second switch means, comprising means for computing the attenuation of a line under test, and means for indicating a fault condition when the computed attenuation is above a predetermined threshold.
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15. A method of testing one of a plurality of high speed digital lines, comprising the steps of:
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a) injecting an AC test signal into a line under test, the line under test being one of the plurality of high speed digital lines; b) receiving the AC test signal at a point where it has propagated down the line under test; c) producing a DC signal having a magnitude deterministically related to the magnitude of the received AC test signal; d) placing the DC signal onto a return line, the return line being another one of the plurality of high speed digital lines; e) receiving the DC signal at a point where it has propagated down the return line; and f) comparing the DC signal to the magnitude of the injected AC signal and determining whether a fault condition exists.
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16. A method of testing one of a plurality of lines, comprising the steps of:
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a) injecting an AC test signal into a line under test, the line under test being one of the plurality of lines; b) receiving the AC test signal at a point where it has propagated down the line under test; c) producing a DC signal having a magnitude deterministically related to the magnitude of the received AC test signal, wherein the producing comprises the substeps of i) producing an intermediate DC signal having a magnitude proportional to the received AC signal, ii) comparing the intermediate DC signal to a threshold, and iii) when the intermediate DC signal is below the threshold, inverting and amplifying the intermediate DC signal; d) placing the DC signal onto another one of the plurality of lines; receiving the DC signal at a point Where it has propagated down the line; and f) comparing the DC signal to the magnitude of the injected AC signal and determining whether a fault condition exists. - View Dependent Claims (17)
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Specification