Technique for estimation of a subscriber line insertion loss
AssigneeTeradyne, Inc.
InventorRoger Faulkner
Life of this patent
Estimating the term…
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.
Claims32
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;
- measuring a capacitance between said selected telephone line and ground;
- applying an AC voltage between said selected telephone line and ground;
- measuring a voltage between said selected telephone line and ground;
- measuring a current in said selected telephone line;
- and
- estimating an insertion loss from said capacitance, said voltage and said current.
An apparatus for estimating insertion loss of a subscriber line comprising:
- a connection element placing both wires of a selected telephone line in electrical contact with each other;
- a 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 voltage measuring element coupled to said connection element and measuring a resulting voltage between said selected telephone line and ground;
- a 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 capacitance measuring element, said voltage measuring element and said current measuring element, said calculation element determining an insertion loss from said capacitance, said resulting voltage and said current.
A computer program product for a test unit, the computer program product comprising a computer usable medium having computer readable code thereon, including program code comprising:
- instructions and data for causing a processor to perform at least one of interconnecting two wires of a phone line to each other, measuring a capacitance between said phone line and ground, applying an AC voltage between said phone line and ground, measuring a resulting voltage between said phone line and ground, measuring a current of said telephone line, and estimating an insertion loss of said phone line.
Dependencies are inferred from the claim text.