US3860873A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fm transmission system
Assignee: Tape Athon Corp
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Filing: 1971-10-01
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Granted: 1975-01-14
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Expires: 1991-10-01
Abstract
Abstract An FM transmission system is disclosed in which audio signals are stereo multiplexed prior to being applied to produce corresponding FM signals having carrier frequencies outside of the normal FM commercial transmission band of 88-108 megahertz. The FM signals are combined onto the cable of a cable television system for transmission to subscribers equipped with decoding circuitry. The decoding circuitry responds to FM signals which have been separated from television signals by shifting the carrier frequencies of the FM signals into the normal FM band for use with the subscriber''s standard FM receiver. The resulting FM transmission system provides for the transmission of private FM programs originating at the television cable station or head-end over the cable to subscribers who are equipped to receive such programs, without interference with either the television signals or commercially broadcast FM signals carried by the cable.
Inventors
- 👤 John E Ringstad
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 11:55
CPC Classifications
H; H04; H04B; H04B14/00; H04B14/002; H04B14/006
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
231 words
For use in a cable television system, apparatus for transmitting at least one audio signal through the system as an FM signal which is outside the normal commercial FM transmission band comprising: means including transducer means for providing a plurality of audio signals; means responsive to the audio signals for stereo multiplexing the audio signals; means coupled to the stereo multiplexing means and responsive to the stEreo multiplexed audio signals for generating corresponding FM stereo multiplexed signals having carrier frequencies outside the normal commercial FM transmission band; and means coupled to a cable of a cable television system and responsive to the FM signals for transmitting the FM signals over the cable when coupled thereto, said transmitting means comprising a transformer tree coupling the plurality of FM signals to the cable, the transformer tree comprising a different symmetrical bifilar transformer coupled to receive each pair of the FM signals at a pair of inputs thereof, a different asymmetrical bifilar transformer coupled to each symmetrical bifilar transformer and having a single output, the single output of each pair of symmetrical bifilar transformers being coupled to the inputs of a symmetrical bifilar transformer intercoupled with an asymmetrical bifilar transformer having a single output so that a single output of an asymmetrical bifilar transformer comprises a single output of the transformer tree, the single output of the transformer tree being coupled to the cable.
Claim 2
Dependent Claim
231 words
For use in a cable television system, apparatus for transmitting at least one audio signal through the system as an FM signal which is outside the normal commercial FM transmission band comprising: means including transducer means for providing a plurality of audio signals; means responsive to the audio signals for stereo multiplexing the audio signals; means coupled to the stereo multiplexing means and responsive to the stEreo multiplexed audio signals for generating corresponding FM stereo multiplexed signals having carrier frequencies outside the normal commercial FM transmission band; and means coupled to a cable of a cable television system and responsive to the FM signals for transmitting the FM signals over the cable when coupled thereto, said transmitting means comprising a transformer tree coupling the plurality of FM signals to the cable, the transformer tree comprising a different symmetrical bifilar transformer coupled to receive each pair of the FM signals at a pair of inputs thereof, a different asymmetrical bifilar transformer coupled to each symmetrical bifilar transformer and having a single output, the single output of each pair of symmetrical bifilar transformers being coupled to the inputs of a symmetrical bifilar transformer intercoupled with an asymmetrical bifilar transformer having a single output so that a single output of an asymmetrical bifilar transformer comprises a single output of the transformer tree, the single output of the transformer tree being coupled to the cable.
Claim 3
Dependent Claim
207 words
For use in a cable television system in which at least one FM signal having a carrier frequency outside the normal commercial FM transmission band is transmitted over a cable for the system, apparatus receiving and decoding the transmitted FM signal for reception by an FM receiver comprising: means responsive to FM signals having carrier frequencies within the normal commercial FM transmission band for passing the signals without substantial alteration; means providing a desired carrier frequency within the normal commercial FM transmission band; means responsive to the transmitted FM signal and to the desired carrier frequency for shifting the carrier frequency of the transmitted FM signal to the desired carrier frequency; and means coupled between a cable of the cable television system and the carrier frequency shifting means for separating FM signals transmitted over the cable from television signals also transmitted over the cable, said means comprising an asymmetrical bifilar transformer having opposite terminals, one of which is coupled to a terminal for receiving television signals, and a tap coupled to the cable, and a symmetrical bifilar transformer having opposite terminals respectively coupled to the other terminal of the asymmetrical bifilar transformer and to a reference potential and a tap coupled to the carrier frequency shifting means.
Claim 4
Dependent Claim
207 words
For use in a cable television system in which at least one FM signal having a carrier frequency outside the normal commercial FM transmission band is transmitted over a cable for the system, apparatus receiving and decoding the transmitted FM signal for reception by an FM receiver comprising: means responsive to FM signals having carrier frequencies within the normal commercial FM transmission band for passing the signals without substantial alteration; means providing a desired carrier frequency within the normal commercial FM transmission band; means responsive to the transmitted FM signal and to the desired carrier frequency for shifting the carrier frequency of the transmitted FM signal to the desired carrier frequency; and means coupled between a cable of the cable television system and the carrier frequency shifting means for separating FM signals transmitted over the cable from television signals also transmitted over the cable, said means comprising an asymmetrical bifilar transformer having opposite terminals, one of which is coupled to a terminal for receiving television signals, and a tap coupled to the cable, and a symmetrical bifilar transformer having opposite terminals respectively coupled to the other terminal of the asymmetrical bifilar transformer and to a reference potential and a tap coupled to the carrier frequency shifting means.
References Cited (Backward Citations)
US2463505A
Cited
US2531199A
Cited
US2704362A
Cited
US2831105A
Cited
US3135922A
Cited
US3333198B1
Cited
US3333198A
Cited
US3534172A
Cited
US3665311A
Cited
US3701946A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-01-13 | 1978-07-15 | 1979-01-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-01-13 | 1982-07-15 | 1983-01-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-01-13 | 1986-07-15 | 1987-01-14 | $7700.00 | Window Closed / Lapsed |