High density digital transmission system
US4135057A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 5, 1977 |
| Grant date | Jan 16, 1979 |
| Priority date | — |
| Expiry date | Dec 5, 1997 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L25/497
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A high density bandlimited digital transmission system with a transmitter and a receiver connected by a radio path with an end-to-end channel transfer function selected to form at the receiver either raised cosine pulses or partial response pulses. The transmitter is partitioned or divided into an active pulse forming network and a passive pulse shaping and bandlimiting network. The active and passive networks are concatenated and in combination provide an optimal transmitter-receiver combination for raised cosine or for partial response signaling. Transmit and receive filters provide optimal signal pulse shaping while meeting specified out-of-band signal suppression. In-phase and quadrature phase carriers (I and Q channels) work with rectangular or half-wave sinusoidal modulating pulses. Further, time-offset or time-coincident pulses on each of the respective I and Q channels are used. Multi-level embodiments are also disclosed. Receivers using time-offset modulation forms allowing coherent detection using VSB and SSB techniques with resulting simplification of the receiver structures. This mode of operation is possible without the use of sideband separation filters at the transmi…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.