Modem for RF subscriber telephone system
US4764940A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 24, 1986 |
| Grant date | Aug 16, 1988 |
| Priority date | — |
| Expiry date | Nov 24, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/2032
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A modulator for a modem, said modulator being adapted to convert a bit stream, wherein each given number of successive bits defines a symbol, into a phase modulated intermediate frequency (IF) signal, the symbols in the modulator section being phase modulated DPSK conversion. The phase modulated symbols are then digitally filtered to provide a filtered signal comprising time shared, digital in-phase and quadrature phase components that, when converted into an analog signal, provides a modulation signal of a frequency that is centered about a predetermined frequency and deviates therefrom in accordance with the value of the phase modulated symbol. The filtered signal, after being converted to an analog signal is then filtered and passed to a mixer for up conversion to an IF signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.