US3911364A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cophasing combiner with cochannel signal selector
Assignee: AT&T Inc
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Filing: 1974-05-09
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Granted: 1975-10-07
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Expires: 1994-05-09
Abstract
Abstract A diversity cophasing combiner is adapted to select a single signal from among a plurality of cochannel signals transmitted from different sources. The various sources transmit signals having PSK information modulation and having, in addition, pilot tag modulation uniquely associated with each source. The composite of the transmission from all sources is received by each element of a phased array antenna and applied to its associated diversity branch. The outputs of the diversity branches are combined and the combined output is processed to select one tag and produce a loop signal uniquely identified by the one selected tag. The processing is arranged so that when this loop signal is mixed with each branch input, the upper sideband product of the loop signal and the one received signal having the selected tag contains a distinctive cophasing phase angle, but it is stripped of information and tagging modulation. Any unselected received signal produces a product containing some unremoved information or tagging modulation and it is therefore distinguishable. Only the one modulation-free product derived from the received signal having the selected tag is mixed with the total branch input to yield the cophased branch output, and thus only the transmission having the selected tag contributes to the cophased combined output.
Inventors
- 👤 Rollin Edward Langseth
- 👤 Yu Shuan Yeh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 22:39
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/02; H04B7/04; H04B7/08; H04B7/0837; H04B7/084
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
189 words
A transmission system comprising, a plurality of spaced transmitting sources, each source transmitting a signal at a common carrier frequency but having PSK information modulation and pilot tag modulation uniquely associated with that source, and a diversity receiver having a plurality of branches, the receiver including means in each of the branches for receiving a branch input consisting of all of the signals transmitted from the plurality of sources, means for combining the outputs of each branch to produce a combined output, means for operating on the combined output to select the one unique pilot tag modulation associated with a selected source and produce a loop signal uniquely identified by the selected one unique pilot tag modulation, means in each of the branches for combining the loop signal with the branch input to produce the branch output, a portion of said branch output being derived from the one signal of the branch input having the one selected unique pilot tag modulation exclusive of all other signals of the branch input, said portion being cophased with the corresponding portion of each other Branch output derived exclusively from the selected source.
Claim 2
Dependent Claim
189 words
A transmission system comprising, a plurality of spaced transmitting sources, each source transmitting a signal at a common carrier frequency but having PSK information modulation and pilot tag modulation uniquely associated with that source, and a diversity receiver having a plurality of branches, the receiver including means in each of the branches for receiving a branch input consisting of all of the signals transmitted from the plurality of sources, means for combining the outputs of each branch to produce a combined output, means for operating on the combined output to select the one unique pilot tag modulation associated with a selected source and produce a loop signal uniquely identified by the selected one unique pilot tag modulation, means in each of the branches for combining the loop signal with the branch input to produce the branch output, a portion of said branch output being derived from the one signal of the branch input having the one selected unique pilot tag modulation exclusive of all other signals of the branch input, said portion being cophased with the corresponding portion of each other Branch output derived exclusively from the selected source.
Claim 3
Dependent Claim
125 words
A transmission system as claimed in claim 1 wherein means for combining the loop signal with the branch input includes means for mixing the loop signal and the branch input to produce a summation of the upper sideband products, the one product derived from the signal of the branch input having the one selected tag being uniquely distinguishable from all other upper sideband products by the absence of both information modulation and pilot tagging information, narrowband filter means for separating the desired product from all other sideband products, and means for mixing the desired product with the branch input to produce the branch output having a cophased portion derived exclusively from the one signal of the branch input having the one selected pilot tag modulation.
Claim 4
Dependent Claim
58 words
A transmission system as claimed in claim 1 wherein one of the plurality of sources provides no pilot tag modulation, its transmission being uniquely identified by the lack of a pilot tag modulation, and the means for operating on the combined output is arranged to select a pilot tag modulation associated with another of the plurality of sources.
Claim 5
Dependent Claim
104 words
A transmission system as claimed in claim 1 wherein said means for operating on the combined output to produce a loop signal includes means for processing the combined output to remove the PSK information modulation, a variable bandpass filter to which the output of the processing means is applied, the passband of the filter being selectively variable to pass a signal having a frequency identifying the one selected pilot tag modulation to the exclusion of all other signals having other pilot tag modulations, and mixing means for generating from the filtered signal the loop signal uniquely identified by the one selected pilot tag modulation.
Claim 6
Dependent Claim
72 words
A transmission system as claimed in claim 4 wherein the pilot tag modulation is by linear phase shift which produces a frequency offset, and the processing means raises the combined output to the Nth power, where N is the phase of the PSK modulation, the output raised to the Nth power containing a cw signal having no information modulation, but having a frequency component N times the one selected pilot tag modulation.
Claim 7
Dependent Claim
34 words
A transmission system as claimed in claim 5 wherein the bandpass filter passes only the cw signal having no information modulation, but having a frequency component N times the one selected pilot tag modulation.
Claim 8
Dependent Claim
193 words
In a diversity receiver having a plurality of branches and being responsive to transmissions from a plurality of spaced transmitting sources, each source transmitting a signal having a common carrier frequency with PSK information modulation and pilot tag modulation uniquely associated with that source, cophasing apparatus comprising, means for combining the output of each branch to produce a combined output containing a cophased selected portion, and means for preconditioning the combined output to produce a loop signal uniquely identified by one selected pilot tag, each of the branches including: means for receiving as a branch input each of the pilot tag modulated transmissions, means for fixing the loop signal with the branch input to produce a combination of upper sideband products, the one product derived from the part of the branch input having the selected tag modulation being uniquely distinguishable from all other upper sideband products by the absence of both information modulation and pilot tag modulation, narrowband filter means for separating the one product from all other upper sideband products, and means for mixing the desired product with the branch input to produce the branch output for application to the combining means.
Claim 9
Dependent Claim
193 words
In a diversity receiver having a plurality of branches and being responsive to transmissions from a plurality of spaced transmitting sources, each source transmitting a signal having a common carrier frequency with PSK information modulation and pilot tag modulation uniquely associated with that source, cophasing apparatus comprising, means for combining the output of each branch to produce a combined output containing a cophased selected portion, and means for preconditioning the combined output to produce a loop signal uniquely identified by one selected pilot tag, each of the branches including: means for receiving as a branch input each of the pilot tag modulated transmissions, means for fixing the loop signal with the branch input to produce a combination of upper sideband products, the one product derived from the part of the branch input having the selected tag modulation being uniquely distinguishable from all other upper sideband products by the absence of both information modulation and pilot tag modulation, narrowband filter means for separating the one product from all other upper sideband products, and means for mixing the desired product with the branch input to produce the branch output for application to the combining means.
Claim 10
Dependent Claim
58 words
In a diversity receiver cophasing apparatus as claimed in claim 7 wherein one of the plurality of sources provides no pilot tag modulation, its transmission being uniquely identified by the lack of a pIlot tag modulation, and the means for preconditioning the combined output is adapted to select a pilot tag modulation associated with another of the sources.
Claim 11
Dependent Claim
95 words
In a diversity receiver cophasing apparatus as claimed in claim 7 wherein the means for preconditioning the combined output includes means for processing the combined output to remove the PSK information modulation, a variable bandpass filter to which the output of the processing means is applied, the passband of the filter being selectively variable to pass a signal having a frequency identifying the one selected pilot tag to the exclusion of all other pilot tags, and mixing means for generating from the filtered signal the loop signal uniquely identified by the one selected pilot tag.
Claim 12
Dependent Claim
74 words
In a diversity receiver, cophasing apparatus as claimed in claim 9 wherein the pilot tag modulation is by linear phase shift which produces a frequency offset, and the processing means raises the combined output to the Nth power, where N is the phase of the PSK modulation, the output raised to the Nth power containing a cw signal having no information modulation, but having a frequency component N times the one selected pilot tag.
Claim 13
Dependent Claim
36 words
In a diversity receiver, cophasing apparatus as claimed in claim 9 wherein the bandpass filter passes only the cw signal having no information modulation, but having a frequency component N times the one selected pilot tag.
Claim 14
Dependent Claim
188 words
A diversity cophasing receiver of the type having a plurality of branches, means for combining the branch outputs to produce a combined output, feedback means for applying a loop signal derived from the combined output to the individual branches to produce a cophasing signal within each branch, means for combining the cophasing signal with the branch input to produce a cophased branch output, characterized in that the receiver is responsive to transmissions from a plurality of spaced transmitting sources, each source transmitting a signal having a common carrier frequency with PSK information modulation and pilot tag modulation uniquely associated with that source, and the feedback means includes means for processing the combined output to remove the PSK information modulation, a variable bandpass filter to which the output of the processing means is applied, the passband of the filter being selectively variable to pass a signal having a frequency identifying the one selected pilot tag modulation to the exclusion of all other signals having other pilot tag modulations, and mixing means for generating from the filtered signal the loop signal uniquely identified by the one selected pilot tag modulation.
Claim 15
Dependent Claim
188 words
A diversity cophasing receiver of the type having a plurality of branches, means for combining the branch outputs to produce a combined output, feedback means for applying a loop signal derived from the combined output to the individual branches to produce a cophasing signal within each branch, means for combining the cophasing signal with the branch input to produce a cophased branch output, characterized in that the receiver is responsive to transmissions from a plurality of spaced transmitting sources, each source transmitting a signal having a common carrier frequency with PSK information modulation and pilot tag modulation uniquely associated with that source, and the feedback means includes means for processing the combined output to remove the PSK information modulation, a variable bandpass filter to which the output of the processing means is applied, the passband of the filter being selectively variable to pass a signal having a frequency identifying the one selected pilot tag modulation to the exclusion of all other signals having other pilot tag modulations, and mixing means for generating from the filtered signal the loop signal uniquely identified by the one selected pilot tag modulation.
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) | 1978-10-06 | 1979-04-07 | 1979-10-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-06 | 1983-04-07 | 1983-10-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-06 | 1987-04-07 | 1987-10-07 | $7700.00 | Window Closed / Lapsed |