US3789149A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Code division multiplex system
Assignee: Plessey Telecommunications Research Ltd
•
Filing: 1972-06-09
•
Granted: 1974-01-29
•
Expires: 1992-06-09
Abstract
Abstract In digital transmission systems for use over H.F. radio links, the effects of multi-path propagation can be reduced by limiting the minimum duration of a signal element. The invention is concerned with a system for use when a transmission rate much greater than that which can be accommodated on a single channel if this minimum element duration is maintained. A code-division multiplex system is used. A first plurality of multi-level signals each represents a plurality of elements of the incoming signal. An orthogonal transformation matrix produces a second plurality of multi-level signals, the level of each of which is dependent on all said first plurality of multi-level signals. A time-division-multiplex signal is then produced from said second plurality of multi-level signals and used to modulate a carrier signal.
Inventors
- 👤 A Clark
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:44
CPC Classifications
H; H04; H04L; H04L5/00; H04L5/02
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
193 words
For use in a code division multiplex electrical signalling system in which digital signals are transmitted at a lower element rate than that of the signals to be transmitted, a receiver comprising sampling means for sampling the received signal once during each element thereof to produce a first plurality of multi-level signals, matrix means comprising at least one orthogonal transformation matrix responsive to said sampling means for producing a second plurality of multi-level signals from said first plurality thereof and decoding means responsive to said matrix means for producing a plurality of signal elements from each multi-level signal of said second plurality thereof, wherein said decoding means comprises polarity detection and level detection means adapted to produce a respective first binary signal and a respective second binary signal for each multi-level signal of said second plurality thereof, each of said first binary signals having the same polarity as the corresponding multilevel signal and each of said second binary signals having a first polarity when the corresponding multi-level signal has a magnitude greater than a predetermined level and a second polarity when said corresponding multi-level signal has a polarity less than said predetermined level.
Claim 2
Dependent Claim
193 words
For use in a code division multiplex electrical signalling system in which digital signals are transmitted at a lower element rate than that of the signals to be transmitted, a receiver comprising sampling means for sampling the received signal once during each element thereof to produce a first plurality of multi-level signals, matrix means comprising at least one orthogonal transformation matrix responsive to said sampling means for producing a second plurality of multi-level signals from said first plurality thereof and decoding means responsive to said matrix means for producing a plurality of signal elements from each multi-level signal of said second plurality thereof, wherein said decoding means comprises polarity detection and level detection means adapted to produce a respective first binary signal and a respective second binary signal for each multi-level signal of said second plurality thereof, each of said first binary signals having the same polarity as the corresponding multilevel signal and each of said second binary signals having a first polarity when the corresponding multi-level signal has a magnitude greater than a predetermined level and a second polarity when said corresponding multi-level signal has a polarity less than said predetermined level.
Claim 3
Dependent Claim
18 words
A receiver as claimed in claim 1, including demodulation means comprising a phase-locked oscillator and a switched inverter.
Claim 4
Dependent Claim
17 words
A receiver as claimed in claim 1, in which said matrix means comprises a single transformation matrix.
Claim 5
Dependent Claim
66 words
A receiver as claimed in claim 1, in which said matrix means comprises first and second transformation matrices, the first transformation matrix being arranged to be responsive to signals modulating a first carrier signal and the second transformation matrix being arranged to be responsive to signals transmitted by a second carrier signal having the same frequency as the first carrier signal but being in phase-quadrature thereto.
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) | 1977-01-28 | 1977-07-30 | 1978-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-28 | 1981-07-30 | 1982-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-28 | 1985-07-30 | 1986-01-29 | $7700.00 | Window Closed / Lapsed |