US3745464A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Radio system with feedback for fading compensation
Assignee: AT&T Inc
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Filing: 1971-12-02
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Granted: 1973-07-10
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Expires: 1991-12-02
Abstract
Abstract A nondiversity radio system provides compensation for multipath fading by means of continuous amplitude feedback. Intelligence is transmitted from one station by means of frequency modulation, while amplitude modulation is caused by the fading en route. At the other station the received amplitude envelope is fed back as part of a frequency modulated, return intelligence signal. The feedback envelope is used at the first station to amplitude modulate the subsequent transmission to precompensate for the anticipated fade and produce fade-free reception at the other station. The system is especially well suited for mobile radio telephone applications since fading can be eliminated at a relatively simple, single branch mobile station.
Inventors
- 👤 W Lee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:56
CPC Classifications
H; H04; H04W; H04W52/00; H04W52/04
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
246 words
A radio communication system with compensation for multipath fading comprising: means at a first station for generating a forward signal containing forward intelligence modulation, means at the first station for transmitting the generated forward signal and for receiving a return signal containing return intelligence modulation, means at a second station for transmitting the return signal and for receiving the forward signal, sensing means for continUously detecting at the second station the amplitude envelope of the received forward signal and producing an indication thereof, said amplitude indication being representative of the multipath fading experienced by the forward signal in the transmission path between the first and second stations, feedback means at the second station for incorporating the amplitude indication as part of a return intelligence input and for modulating the input onto the return signal, separation means at the first station for removing the amplitude indication from the modulation of the return signal received at the first station, compensation means at the first station consisting exclusively of linear elements for producing from the removed amplitude indication a compensating signal having an amplitude variation derived from the amplitude variation of the detected envelope, the compensating signal being linearly related to the time varying difference between the amplitude of the generated forward signal and the detected amplitude envelope, and said means for transmitting the generated forward signal including means for amplitude modulating the generated forward signal in response to the compensating signal to precompensate for the transmission path fading.
Claim 2
Dependent Claim
246 words
A radio communication system with compensation for multipath fading comprising: means at a first station for generating a forward signal containing forward intelligence modulation, means at the first station for transmitting the generated forward signal and for receiving a return signal containing return intelligence modulation, means at a second station for transmitting the return signal and for receiving the forward signal, sensing means for continUously detecting at the second station the amplitude envelope of the received forward signal and producing an indication thereof, said amplitude indication being representative of the multipath fading experienced by the forward signal in the transmission path between the first and second stations, feedback means at the second station for incorporating the amplitude indication as part of a return intelligence input and for modulating the input onto the return signal, separation means at the first station for removing the amplitude indication from the modulation of the return signal received at the first station, compensation means at the first station consisting exclusively of linear elements for producing from the removed amplitude indication a compensating signal having an amplitude variation derived from the amplitude variation of the detected envelope, the compensating signal being linearly related to the time varying difference between the amplitude of the generated forward signal and the detected amplitude envelope, and said means for transmitting the generated forward signal including means for amplitude modulating the generated forward signal in response to the compensating signal to precompensate for the transmission path fading.
Claim 3
Dependent Claim
40 words
A radio communication system as claimed in claim 1 wherein said compensation means includes means for linearly amplifying the amplitude indication and means for taking the difference between the amplitude of the generated forward signal and the amplified amplitude indication.
Claim 4
Dependent Claim
28 words
A radio communication system as claimed in claim 1 wherein forward intelligence and return intelligence are frequency modulated onto carriers to produce the forward and return signals respectively.
Claim 5
Dependent Claim
32 words
A radio communication system as claimed in claim 1 wherein said means for amplitude modulating the generated forward signal is a multiplier for multiplicatively combining the forward signal and the compensating signal.
Claim 6
Dependent Claim
76 words
A radio communication system as claimed in claim 1 wherein said system is a mobile radio system in which the first station is a base station and the second station is a mobile station and the forward and return signals are frequency modulated signals transmitted at frequencies in the 1 GHz range, and wherein said sensing means includes means for producing the amplitude indication at a frequency above the other part of the return intelligence input.
Claim 7
Dependent Claim
232 words
A radio communication system with compensation for multipath fading comprising: means at a first station for generating a forward signal containing forward intelligence modulation, means at the first station for transmitting the generated forward signal and for receiving a return signal containing return intelligence modulation, means at a second station for transmitting the return signal and for receiving the forward signal, sensing means for continuously detecting at the second station the amplitude envelope of the received forward signal and producing an indication thereof, said amplitude indication being representative of the multipath fading experienced by the forward signal in the transmission path between the first and second stations, feedback means at the second station for incorporating the amplitude indication as part of a return intelligence input and for modulating the input onto the return signal, separation means at the first station for removing the amplitude indication from the modulation of the return signal received at the first station, compensation means at the first station including nonlinear elements for producing from the removed amplitude indication a compensating signal having an amplitude variation derived from the amplitude variation of the detected envelope, the compensating signal being reciprocally related to the time varying amplitude indication, and said means for transmitting the generated forward signal including means for amplitude modulating the generated forward signal in response to the cOmpensating signal to precompensate for the transmission path fading.
Claim 8
Dependent Claim
232 words
A radio communication system with compensation for multipath fading comprising: means at a first station for generating a forward signal containing forward intelligence modulation, means at the first station for transmitting the generated forward signal and for receiving a return signal containing return intelligence modulation, means at a second station for transmitting the return signal and for receiving the forward signal, sensing means for continuously detecting at the second station the amplitude envelope of the received forward signal and producing an indication thereof, said amplitude indication being representative of the multipath fading experienced by the forward signal in the transmission path between the first and second stations, feedback means at the second station for incorporating the amplitude indication as part of a return intelligence input and for modulating the input onto the return signal, separation means at the first station for removing the amplitude indication from the modulation of the return signal received at the first station, compensation means at the first station including nonlinear elements for producing from the removed amplitude indication a compensating signal having an amplitude variation derived from the amplitude variation of the detected envelope, the compensating signal being reciprocally related to the time varying amplitude indication, and said means for transmitting the generated forward signal including means for amplitude modulating the generated forward signal in response to the cOmpensating signal to precompensate for the transmission path fading.
Claim 9
Dependent Claim
29 words
A radio communication system as claimed in claim 6 wherein said compensation means includes means for nonlinearly amplifying the amplitude indication and means for inverting the amplified amplitude indication.
Claim 10
Dependent Claim
30 words
A radio communication system as claimed in claim 6 wherein the forward intelligence and the return intelligence are frequency modulated onto carriers to produce the forward and return signals respectively.
Claim 11
Dependent Claim
32 words
A radio communication system as claimed in claim 6 wherein said means for amplitude modulating the generated forward signal is a multiplier for multiplicatively combining the forward signal and the compensating signal.
Claim 12
Dependent Claim
76 words
A radio communication system as claimed in claim 6 wherein said system is a mobile radio system in which the first station is a base station and the second station is a mobile station and the forward and return signals are frequency modulated signals transmitted at frequencies in the 1 GHz range, and wherein said sensing means includes means for producing the amplitude indication at a frequency above the other part of the return intelligence input.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-07-09 | 1977-01-08 | 1977-07-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-09 | 1981-01-08 | 1981-07-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-09 | 1985-01-08 | 1985-07-10 | $7700.00 | Window Closed / Lapsed |