US3689841A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Communication system for eliminating time delay effects when used in a multipath transmission medium
Assignee: SIGNATRON Inc A CORP OF DE
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Filing: 1970-10-23
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Granted: 1972-09-05
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Expires: 1990-10-23
Abstract
Abstract A communication system for providing effective multipath transmission without intermodulation or other distortion effects normally arising from the transmission through a dispersive medium, such as multipath troposcatter communication links. In the invention the analog information is used to phase or amplitude modulate a transmitter signal and digital information is used to frequency and phase modulate such signal in a hybrid modulation process which is readily adapted to permit alternate analog and digital modulation, simultaneous analog and digital modulation, or sole analog or sole digital modulation over periodically occurring frame intervals of time. At the receiver the multipath signal is appropriately gated to select only those portions of the received signal which are the least affected by time delays introduced by the multipath transmission, such selected portions being demodulated to reconstruct the analog and digital information which has been transmitted.
Inventors
- 👤 Phillip A Bello
- 👤 Howard C Salwen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:14
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/22
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
326 words
A system for communicating analog and digital information through a dispersive transmission medium, said system comprising: a transmitter including means for generating a carrier signal; hybrid modulating means responsive to said analog and digital information for modulating said carrier signal to produce a carrier modulated signal in which said analog and said digital information are transmitted periodically over selected frame intervals of time, said hybrid modulating means comprising: means responsive to said analog information for producing periodic sampled amplitudes of said analog information; means responsive to said periodic sampled amplitudes for modulating said carrier signal as a function of said periodically sampled amplitudes of said analog information; means responsive to said digital information for modulating said carrier signal as a function of said digital information; and timing means for controlling said hybrid modulating means so that said carrier modulated signal includes both said analog and said digital information during each said frame interval of time; and means for transmitting said carrier modulated signal through said dispersive transmission medium; and a receiver including means for receiving said carrier modulated signal as transmitted through said dispersive transmission medium; gating means for passing selected portions of said received signal during each said frame interval of time, said gating means being actuated to pass each said selected portions only during a selected time interval within each said frame time interval which is sufficiently removed from the leading portion of each said frame time interval to avoid time delay effects introduced by said dispersive transmission medium; detecting means responsive to said selected portions of said received signal during each said frame interval of time for detecting said modulation characteristics thereof during each said frame interval of time; time synchronization means responsive to said receiving means for synchronizing the operations of said gating means and said detecting means; and means responsive to said detected modulation characteristics during each said frame interval of time for reconstructing said analog information and said digital information.
Claim 2
Independent Claim
326 words
A system for communicating analog and digital information through a dispersive transmission medium, said system comprising: a transmitter including means for generating a carrier signal; hybrid modulating means responsive to said analog and digital information for modulating said carrier signal to produce a carrier modulated signal in which said analog and said digital information are transmitted periodically over selected frame intervals of time, said hybrid modulating means comprising: means responsive to said analog information for producing periodic sampled amplitudes of said analog information; means responsive to said periodic sampled amplitudes for modulating said carrier signal as a function of said periodically sampled amplitudes of said analog information; means responsive to said digital information for modulating said carrier signal as a function of said digital information; and timing means for controlling said hybrid modulating means so that said carrier modulated signal includes both said analog and said digital information during each said frame interval of time; and means for transmitting said carrier modulated signal through said dispersive transmission medium; and a receiver including means for receiving said carrier modulated signal as transmitted through said dispersive transmission medium; gating means for passing selected portions of said received signal during each said frame interval of time, said gating means being actuated to pass each said selected portions only during a selected time interval within each said frame time interval which is sufficiently removed from the leading portion of each said frame time interval to avoid time delay effects introduced by said dispersive transmission medium; detecting means responsive to said selected portions of said received signal during each said frame interval of time for detecting said modulation characteristics thereof during each said frame interval of time; time synchronization means responsive to said receiving means for synchronizing the operations of said gating means and said detecting means; and means responsive to said detected modulation characteristics during each said frame interval of time for reconstructing said analog information and said digital information.
Claim 3
Dependent Claim
62 words
A system in accordance with claim 1 wherein said modulating means responsive to said digital information modulates the frequency characteristics and the phase characteristics of said carrier signal; said detecting means detects the frequency and phase modulation characteristics of said selected portions of said received signal; and said reconstructing means is responsive to said detected and said frequency and phase modulation characteristics.
Claim 4
Dependent Claim
23 words
A system in accordance with claim 1 wherein said modulating means responsive to said analog information modulates the phase of said carrier signal.
Claim 5
Dependent Claim
57 words
A system in accordance with claim 2, wherein said modulating means responsive to said analog information modulates the amplitude of said carrier signal; said detecting means detects the frequency, phase and amplitude modulation characteristics of said selected portions of said received signal; and said reconstructing means is responsive to said detected frequency, phase and amplitude modulation characteristics.
Claim 6
Dependent Claim
58 words
A system in accordance with claim 1 wherein said timing means is adapted to control said hybrid modulating means to produce a carrier modulated signal in which said analog information is transmitted during one-half of said frame interval of time and in which said digital information is transmitted during the other half of said frame interval of time.
Claim 7
Dependent Claim
68 words
A system in accordance with claim 1 wherein said timing means is adapted to control said hybrid modulating means to produce a carrier modulated signal in which said analog information and a portion of said digital information are tRansmitted during one-half of said frame interval of time and in which another portion of said digital information is transmitted during the other half of said frame interval of time.
Claim 8
Dependent Claim
78 words
A system in accordance with claim 1 wherein said timing means is adapted to control said hybrid modulating means to produce a carrier modulated signal in which one portion of said analog information and one portion of said digital information are transmitted during one-half of said frame interval of time and in which another portion of said analog information and another portion of said digital information are transmitted during the other half of said frame interval of time.
Claim 9
Dependent Claim
76 words
A system in accordance with claim 3 wherein said modulating means responsive to said analog information includes means for sampling the amplitude of said analog information at discrete time intervals; means responsive to said sampled amplitude information for producing a sequence of pulse signals having amplitudes during said discrete time intervals representative of said sampled amplitudes; and means responsive to said pulse signals for modulating the phase of said carrier signal in accordance with said amplitudes.
Claim 10
Dependent Claim
76 words
A system in accordance with claim 4 wherein said modulating means responsive to said analog information includes means for sampling the amplitude of said analog information at discrete time intervals; means responsive to said sampled amplitude information for producing a sequence of pulse signals having amplitudes during said discrete time intervals representative of said sampled amplitudes; and means responsive to said pulse signals for modulating the amplitudes of said carrier signal in accordance with said amplitudes.
Claim 11
Dependent Claim
36 words
A system in accordance with claim 11 wherein said means responsive to said digital information includes means for selecting said modulating characteristics from a plurality of discrete frequencies and from a plurality of discrete phase characteristics.
Claim 12
Dependent Claim
54 words
A system in accordance with claim 1 wherein four bits of digital information may be used to modulate said carrier signal to produce a modulated carrier signal of the form where omega IF is the carrier frequency, omega 1 and omega 2 are discrete frequencies, ( + or - ) are discrete phase characteristics.
Claim 13
Independent Claim
225 words
A system for communicating analog information through a dispersive transmission medium, said system comprising a transmitter including means responsive to said analog information for sampling the amplitude thereof at discrete time intervals; means responsive to said sampled amplitude information for producing a sequence of pulse signals having amplitudes during said discrete time intervals representative of said sampled amplitudes; means responsive to said pulse signals for modulating a carrier signal in accordance with said amplitudes to produce an output signal for transmission through said dispersive transmission medium; and a receiver including means for receiving said transmitted signal; gating means for passing selected portions of said received signal, said gating means being actuated to pass each said selected portion only during a selected time interval within each said discrete time interval which is sufficiently removed from the leading portion of each said discrete time interval to avoid time delay effects introduced by said dispersive transmission medium; means for detecting the modulation characteristics of said received signal during each said selected portion; means for producing a sequence of pulse signals having pulse time intervals corresponding to said discrete time intervals which pulse signals have amplitudes representative of said modulation characteristics of said received signal as detected during said selected portions; and means for reconstructing said analog information in response to said amplitudes of said sequence of pulse signals.
Claim 14
Independent Claim
225 words
A system for communicating analog information through a dispersive transmission medium, said system comprising a transmitter including means responsive to said analog information for sampling the amplitude thereof at discrete time intervals; means responsive to said sampled amplitude information for producing a sequence of pulse signals having amplitudes during said discrete time intervals representative of said sampled amplitudes; means responsive to said pulse signals for modulating a carrier signal in accordance with said amplitudes to produce an output signal for transmission through said dispersive transmission medium; and a receiver including means for receiving said transmitted signal; gating means for passing selected portions of said received signal, said gating means being actuated to pass each said selected portion only during a selected time interval within each said discrete time interval which is sufficiently removed from the leading portion of each said discrete time interval to avoid time delay effects introduced by said dispersive transmission medium; means for detecting the modulation characteristics of said received signal during each said selected portion; means for producing a sequence of pulse signals having pulse time intervals corresponding to said discrete time intervals which pulse signals have amplitudes representative of said modulation characteristics of said received signal as detected during said selected portions; and means for reconstructing said analog information in response to said amplitudes of said sequence of pulse signals.
Claim 15
Dependent Claim
56 words
A system in accordaNce with claim 12 wherein said means responsive to said pulse signals modulates the phase characteristics of said carrier signal; said detecting means detects the phase of said received signal; and the amplitudes of said pulse signals of said sequence of pulse signals are representative of said phase characteristics of said received signal.
Claim 16
Dependent Claim
53 words
A system in accordance with claim 12 wherein said means responsive to said pulse signals modulates the amplitude characteristics of said carrier signal; said detecting means detects the amplitudes of said received signal; and said pulse signals of said sequence of pulse signals are representative of said amplitude characteristics of said received signal.
References Cited (Backward Citations)
US2889521A
Cited
US2878318A
Cited
US3226644A
Cited
US3299357A
Cited
US3337691A
Cited
US3523250A
Cited
US3529088A
Cited
US3532988A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-09-05 | 1976-03-06 | 1976-09-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-09-05 | 1980-03-06 | 1980-09-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-09-05 | 1984-03-06 | 1984-09-05 | $7700.00 | Window Closed / Lapsed |