Patent US3798547A successfully refreshed from Google Patents.
US3798547A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Approximate cophasing for diversity receivers
Assignee: AT&T Inc
•
Filing: 1972-12-29
•
Granted: 1974-03-19
•
Expires: 1992-12-29
Abstract
Abstract In a predetection combining diversity receiver approximate cophasing of the individual receptions is temporarily achieved by frequency division of the received signals. These signals, which contain independent phase angles so that any two may be randomly out-of-phase, are each applied to identical frequency division circuits. By dividing each carrier frequency by the factor, N, common to all of the dividing circuits, all of the signals will be initially phased within + OR - pi /N radians. In time, the effect of random phase variations may cause the approximately cophased signals to drift apart. Therefore, the frequency dividing circuits are periodically reset to reestablish approximate cophasing.
Inventors
- 👤 D Reudink
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:27
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/02; H04B7/04; H04B7/08; H04B7/0837; H04B7/084
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
106 words
Diversity apparatus for cophasing and combining a plurality of received signals, each signal having a phase angle randomly related to the phase angle of the others comprising: a plurality of identical frequency dividing means for dividing the frequency and random phase of an input signal applied thereto by a fixed common factor, means for applying each of said plurality of received signals to one of said plurality of frequency dividing means, the outputs of all of said frequency dividing means being approximately cophased, means for combining the approximately cophased signals to produce a combined output, and means for periodically synchronizing the plurality of frequency dividing means.
Claim 2
Dependent Claim
106 words
Diversity apparatus for cophasing and combining a plurality of received signals, each signal having a phase angle randomly related to the phase angle of the others comprising: a plurality of identical frequency dividing means for dividing the frequency and random phase of an input signal applied thereto by a fixed common factor, means for applying each of said plurality of received signals to one of said plurality of frequency dividing means, the outputs of all of said frequency dividing means being approximately cophased, means for combining the approximately cophased signals to produce a combined output, and means for periodically synchronizing the plurality of frequency dividing means.
Claim 3
Dependent Claim
38 words
Diversity apparatus as claimed in claim 1 wherein said means for periodically synchronizing the plurality of frequency dividing means includes means for generating a reset signal having a periodicity integrally related to the frequency of the combined output.
Claim 4
Dependent Claim
32 words
Diversity apparatus as claimed in claim 2 wherein said means for generating the reset signal includes means for frequency dividing the combined output by an integral divisor to produce said reset signal.
Claim 5
Dependent Claim
40 words
Diversity apparatus as claimed in claim 1 further including weighting means for controlling the amplitudes of the outputs of each of said frequency dividing means in response to the amplitude of the signal applied to the respective frequency dividing means.
Claim 6
Dependent Claim
122 words
A diversity receiver comprising: a plurality of elements forming a space diversity antenna array for receiving a plurality of randomly phased signals containing identical frequency modulation, a plurality of identical frequency dividing means for dividing the frequency of an input signal applied thereto by a fixed common factor, means for applying each of said plurality of received signals to an exclusive one of said plurality of frequency dividing means, means for combining the oUtputs of said plurality of frequency dividing means to produce a combined output, means for detecting the combined output to remove the identical frequency modulation, and means for simultaneously resetting the plurality of frequency dividing means on a recurring basis, whereby the frequency divider outputs are continuously approximately cophased.
Claim 7
Dependent Claim
122 words
A diversity receiver comprising: a plurality of elements forming a space diversity antenna array for receiving a plurality of randomly phased signals containing identical frequency modulation, a plurality of identical frequency dividing means for dividing the frequency of an input signal applied thereto by a fixed common factor, means for applying each of said plurality of received signals to an exclusive one of said plurality of frequency dividing means, means for combining the oUtputs of said plurality of frequency dividing means to produce a combined output, means for detecting the combined output to remove the identical frequency modulation, and means for simultaneously resetting the plurality of frequency dividing means on a recurring basis, whereby the frequency divider outputs are continuously approximately cophased.
Claim 8
Dependent Claim
43 words
Diversity receiver as claimed in claim 5 wherein the fixed common factor of said frequency dividing means is N so that any two outputs of the plurality of frequency dividing means have a maximum phase difference of + or - pi /N radians.
Claim 9
Dependent Claim
69 words
A diversity receiver as claimed in claim 6 wherein said frequency dividing means is a digital device which counts the cycles of the input signal applied thereto and changes its output state recurrently upon the occurrence of each N/2 cycles, and said means for simultaneously resetting the plurality of frequency dividing means causes each of said dividing means to begin the count of input cycles at the same time.
Claim 10
Dependent Claim
48 words
A diversity receiver as claimed in claim 5 wherein said means for simultaneously resetting the plurality of frequency dividing means includes means for applying a common reset signal at nonaudio rates to each frequency dividing means, said reset signal being a frequency divided version of the combined output.
References Cited (Backward Citations)
US2975275A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-18 | 1977-09-17 | 1978-03-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-18 | 1981-09-17 | 1982-03-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-18 | 1985-09-17 | 1986-03-19 | $7700.00 | Window Closed / Lapsed |