Patent FR2301488A1 successfully refreshed from Google Patents.
US3846593A
Expired / Lapsed
US
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Telephone line test system
Assignee: Individual
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Filing: 1973-10-31
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Granted: 1974-11-05
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Expires: 1993-10-31
Abstract
Abstract There is disclosed a system for transmitting a complex test signal of several frequency components along a transmission path and cancelling any frequency shift distortion which is introduced by the path. A resolver is used to intoduce a frequency shift in each component at the transmitting end of the path, this frequency shift then being cancelled out as the complex signal travels along the path. The technique is based on the compensating circuit disclosed in my co-pending application Ser. No. 358,663, now U.S. Pat. No. 3,812,433 but the feedback signal, derived at the receiving end of the transmission path and transmitted back to the transmitting end by digital techniques to avoid distortion, is used to cause the resolver to pre-spin in order to introduce a frequency shift in each signal component which is then cancelled during transmission.
Inventors
- 👤 F Bradley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:43
CPC Classifications
H; H04; H04B; H04B3/00; H04B3/02; H04B3/46
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
163 words
A system for transmitting a predetermined complex signal having at least two frequency components therein along a transmission line from the transmitting end to the receiving end thereof, with the frequency shifts which are introduced by the transmission line being cancelled, comprising means for continuously shifting the phase of each frequency component in said complex signal prior to its transmission, means for comparing the phase of one of the received frequency components with the phase of a reference signal of the same frequency to derive a measure of the phase difference, means for transmitting a control signal indicative of the phase difference from the receiving end of the line to the transmitting end of the line, and means for controlling said phase shifting means in accordance with said control signal such that the phase shifts introduced at the transmitting end of the line are cancelled out by the line as said complex signal travels from the transmitting end to the receiving end thereof.
Claim 2
Independent Claim
163 words
A system for transmitting a predetermined complex signal having at least two frequency components therein along a transmission line from the transmitting end to the receiving end thereof, with the frequency shifts which are introduced by the transmission line being cancelled, comprising means for continuously shifting the phase of each frequency component in said complex signal prior to its transmission, means for comparing the phase of one of the received frequency components with the phase of a reference signal of the same frequency to derive a measure of the phase difference, means for transmitting a control signal indicative of the phase difference from the receiving end of the line to the transmitting end of the line, and means for controlling said phase shifting means in accordance with said control signal such that the phase shifts introduced at the transmitting end of the line are cancelled out by the line as said complex signal travels from the transmitting end to the receiving end thereof.
Claim 3
Dependent Claim
48 words
A system in accordance with claim 1 wherein said phase shifting means is a resolver having predetermined quadrature complex signals applied to two inputs thereof, said resolver being operative to continuously shift the phase of each frequency component at the output thereof in accordance with said control signal.
Claim 4
Dependent Claim
48 words
A system in accordance with claim 2 wherein said phase shift controlling means includes means for integrating said control signal and for causing the phase of each frequency component at the output of said resolver to be changed by the value of the integral of said control signal.
Claim 5
Dependent Claim
32 words
A system in accordance with claim 3 wherein said control signal is transmitted from said receiving end to said transmitting end of said transmission line in the form of digitally encoded signals.
Claim 6
Dependent Claim
25 words
A system in accordance with claim 4 wherein said control signal transmitting means includes a high-gain amplifier therein such that the input thereof is nulled.
Claim 7
Dependent Claim
32 words
A system in accordance with clAim 1 wherein said control signal is transmitted from said receiving end to said transmitting end of said transmission line in the form of digitally encoded signals.
Claim 8
Dependent Claim
25 words
A system in accordance with claim 6 wherein said control signal transmitting means includes a high-gain amplifier therein such that the input thereof is nulled.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-11-04 | 1978-05-06 | 1978-11-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-04 | 1982-05-06 | 1982-11-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-04 | 1986-05-06 | 1986-11-05 | $7700.00 | Window Closed / Lapsed |