US3717814A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cophasing diversity communication system with pilot feedback
Assignee: AT&T Inc
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Filing: 1971-09-23
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Granted: 1973-02-20
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Expires: 1991-09-23
Abstract
Abstract Phase corrected intelligence signals are transmitted from a diversity array transmitter and receive in-phase at a monochannel receiver. An individual pilot associated with each diversity branch and frequency separated from the pilots of the other branches is received along with the in-phase intelligence. All of the pilots are fed back, as part of the return modulation, to the diversity transmitter where they are used to establish the proper phase correction for the modulated intelligence transmission.
Inventors
- 👤 M Gans
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 22:37
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/02; H04B7/04; H04B7/06; H04B7/0613; H04B7/0615; H04B7/0619; H04B7/0621; H04B7/0626; H04B7/0602; H04B7/0608; H04B7/061
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
188 words
A communication system for transmitting between a first and a second station comprising: A plurality of diversity branches at the first stations, means at the first station for generating an individual pilot signal in each of a plurality of diversity branches and for transmitting the individual pilot of each branch from an associated one of a plurality of spaced antennas, means at the second station for receiving the plurality of pilot signals, each having a distinctive phase component corresponding to the phase shift experienced during propagation from the first to the second station, means at the second station for deriving from each of the received pilots a feedback pilot and for modulating all of the feedback pilots onto a return transmission while preserving the distinctive phase component of each received pilot, means at the first station for transmitting on each of the plurality of spaced antennas a common forward intelligence signal, and means at the first station for receiving the return transmission and utilizing the distinctive phase component of each feedback pilot to adjust the phase of the forward intelligence signal being transmitted by the corresponding branch antenna.
Claim 2
Dependent Claim
188 words
A communication system for transmitting between a first and a second station comprising: A plurality of diversity branches at the first stations, means at the first station for generating an individual pilot signal in each of a plurality of diversity branches and for transmitting the individual pilot of each branch from an associated one of a plurality of spaced antennas, means at the second station for receiving the plurality of pilot signals, each having a distinctive phase component corresponding to the phase shift experienced during propagation from the first to the second station, means at the second station for deriving from each of the received pilots a feedback pilot and for modulating all of the feedback pilots onto a return transmission while preserving the distinctive phase component of each received pilot, means at the first station for transmitting on each of the plurality of spaced antennas a common forward intelligence signal, and means at the first station for receiving the return transmission and utilizing the distinctive phase component of each feedback pilot to adjust the phase of the forward intelligence signal being transmitted by the corresponding branch antenna.
Claim 3
Dependent Claim
188 words
A communication system for transmitting between a first and a second station comprising: A plurality of diversity branches at the first stations, means at the first station for generating an individual pilot signal in each of a plurality of diversity branches and for transmitting the individual pilot of each branch from an associated one of a plurality of spaced antennas, means at the second station for receiving the plurality of pilot signals, each having a distinctive phase component corresponding to the phase shift experienced during propagation from the first to the second station, means at the second station for deriving from each of the received pilots a feedback pilot and for modulating all of the feedback pilots onto a return transmission while preserving the distinctive phase component of each received pilot, means at the first station for transmitting on each of the plurality of spaced antennas a common forward intelligence signal, and means at the first station for receiving the return transmission and utilizing the distinctive phase component of each feedback pilot to adjust the phase of the forward intelligence signal being transmitted by the corresponding branch antenna.
Claim 4
Dependent Claim
188 words
A communication system for transmitting between a first and a second station comprising: A plurality of diversity branches at the first stations, means at the first station for generating an individual pilot signal in each of a plurality of diversity branches and for transmitting the individual pilot of each branch from an associated one of a plurality of spaced antennas, means at the second station for receiving the plurality of pilot signals, each having a distinctive phase component corresponding to the phase shift experienced during propagation from the first to the second station, means at the second station for deriving from each of the received pilots a feedback pilot and for modulating all of the feedback pilots onto a return transmission while preserving the distinctive phase component of each received pilot, means at the first station for transmitting on each of the plurality of spaced antennas a common forward intelligence signal, and means at the first station for receiving the return transmission and utilizing the distinctive phase component of each feedback pilot to adjust the phase of the forward intelligence signal being transmitted by the corresponding branch antenna.
Claim 5
Dependent Claim
45 words
A communication system as claimed in claim 1 wherein said means for adjusting the phase of the forward intelligence signal includes means in each branch for subtracting from the phase of the forward transmission the phase shift experienced by the pilot transmitted by that antenna.
Claim 6
Dependent Claim
39 words
A communication system as claimed in claim 1 wherein said means for adjusting the phase of the forward intelligence signal includes means in each branch for mixing the forward intelligence signal and the feedback pilot associated with that branch.
Claim 7
Dependent Claim
85 words
A communication system as claimed in claim 1 wherein said means for generating an individual pilot includes in each branch an oscillator for producing a tone separated in frequency from all other individual pilots, and wherein said means for adjusting the phase of the forward intelligence signal includes in each branch a first mixer for mixing the oscillator tone with the forward intelligence signal and a second mixer for mixing the output of the first mixer with the feedback pilot signal associated with that branch.
Claim 8
Dependent Claim
40 words
A communication system as claimed in claim 4 wherein said means for adjusting the phase of the forward intelligence signal includes means for frequency separating the feedback pilots and for applying each of the separated pilots to its associated branch.
Claim 9
Dependent Claim
41 words
A communication system as claimed in claim 4 wherein each branch further includes a combiner for adding the pilot tone and the output from the second mixer, whereby each antenna transmits a phase adjusted intelligence signal and an unadjusted pilot signal.
Claim 10
Dependent Claim
58 words
A communication system as claimed in claim 1 wherein said means at the second station for deriving the feedback pilots includes means for reducing the frequency of the received pilots, and wherein said means for modulating the feedback pilots onto a return transmission includes means for combining a return intelligence signal with the received pilots reduced in frequency.
Claim 11
Dependent Claim
38 words
A communication system as claimed in claim 7 wherein said first station includes means for receiving the return transmission on a plurality of antennas and means for cophasing the return intelligence signals received on the plurality of antennas.
Claim 12
Dependent Claim
52 words
A communication system as claimed in claim 1 wherein said second station is a single branch station having a single antenna which receives in-phase the plurality of Phase adjusted forward intelligence signals transmitted from each branch of the first station, and includes means for separating the received pilots from the in-phase reception.
Claim 13
Dependent Claim
140 words
A diversity transmission system comprising: a diversity station including a plurality of branches, a source for generating forward intelligence, means for transmitting via each branch an independent pilot signal and a forward information signal on which the forward intelligence is modulated, means for receiving a modulated return transmission and applying therefrom to each branch a feedback pilot signal, and means in each branch for adjusting the phase of the forward information signal in accordance with the feedback pilot signal associated with that branch, and a mono-station including a single branch for receiving the plurality of transmitted pilot signals and forward information signals, a source for generating the return intelligence, means for separating the plurality of received pilot signals from the received forward information signals, and means for modulating both the return intelligence and the separated pilots onto the return transmission.
Claim 14
Dependent Claim
140 words
A diversity transmission system comprising: a diversity station including a plurality of branches, a source for generating forward intelligence, means for transmitting via each branch an independent pilot signal and a forward information signal on which the forward intelligence is modulated, means for receiving a modulated return transmission and applying therefrom to each branch a feedback pilot signal, and means in each branch for adjusting the phase of the forward information signal in accordance with the feedback pilot signal associated with that branch, and a mono-station including a single branch for receiving the plurality of transmitted pilot signals and forward information signals, a source for generating the return intelligence, means for separating the plurality of received pilot signals from the received forward information signals, and means for modulating both the return intelligence and the separated pilots onto the return transmission.
References Cited (Backward Citations)
US3267380A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-20 | 1976-08-21 | 1977-02-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-20 | 1980-08-21 | 1981-02-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-20 | 1984-08-21 | 1985-02-20 | $7700.00 | Window Closed / Lapsed |