Technique for estimation of a subscriber line insertion loss
DCFirst Claim
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1. A method of estimating insertion loss of a subscriber line comprising the steps of:
- placing both wires of a selected telephone line in electrical contact with each other;
obtaining a single-ended measurement of a capacitance between said selected telephone line and ground;
applying an AC voltage between said selected telephone line and ground;
obtaining a single-ended measurement of a voltage between said selected telephone line and ground;
obtaining a single-ended measurement of a current in said selected telephone line; and
estimating an insertion loss from said capacitance, said voltage and said current measurements.
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Abstract
A method and apparatus for pre-qualifying lines with respect to estimating the insertion loss of the line is presented. End-to-end insertion loss at high frequencies is estimated from measurements made at low frequencies through the voice switch at the central office of a telephone company. An AC voltage waveform is applied to the telephone line being tested. Real and imaginary components of the resultant waveform are measured. These measurements are captured and used to estimate the insertion loss of the telephone line at frequencies in the range of 40 kHz to 300 kHz.
13 Citations
23 Claims
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1. A method of estimating insertion loss of a subscriber line comprising the steps of:
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placing both wires of a selected telephone line in electrical contact with each other;
obtaining a single-ended measurement of a capacitance between said selected telephone line and ground;
applying an AC voltage between said selected telephone line and ground;
obtaining a single-ended measurement of a voltage between said selected telephone line and ground;
obtaining a single-ended measurement of a current in said selected telephone line; and
estimating an insertion loss from said capacitance, said voltage and said current measurements. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An apparatus for estimating insertion loss of a subscriber line comprising:
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a connection element placing both wires of a selected telephone line in electrical contact with each other;
a single-ended capacitance measuring element coupled to said connection element and measuring a capacitance between said selected telephone line and ground;
a voltage source coupled to said connection element and providing an AC voltage between said selected telephone line and ground;
a single-ended voltage measuring element coupled to said connection element and measuring a resulting voltage between said selected telephone line and ground;
a single-ended current measuring element coupled to said connection element and measuring a current in said selected telephone line; and
a calculation element in communication with said single-ended capacitance measuring element, said single-ended voltage measuring element and said single-ended current measuring element, said calculation element determining an insertion loss from said capacitance, said resulting voltage and said current measurements. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification