Method and apparatus for optical wireless communication
US5926301A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 30, 1996 |
| Grant date | Jul 20, 1999 |
| Priority date | — |
| Expiry date | Aug 30, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/103
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
The wireless communication system, comprising a transmitter and a receiver, operates according to the present PPM-FSK modulation format with two subcarrier frequencies f.sub.1 and f.sub.2. The PPM encoded data on the main data channel 43 are fed to two pulse shaping circuits (30, 31) for additional frequency modulation with said frequencies. The resulting hybrid PPM-FSK signal is used to drive a light source (32). The receiver comprises a photodiode (34) coupled to an amplifier (35). The electrical signal obtained at the output of the amplifier (35) is fed to bandpass filters (36, 37) and envelope detectors (38, 39). The outputs of the envelope detectors are fed to a device (40) designed for pulse restoration and frequency decision. In a first operation, device (40) uses the output signals of the two envelope detectors (38, 39) to derive from them the estimated PPM encoded data signal. It then uses this signal to produce estimated restored pulses and outputs them. Then device (40) uses the output signals of the two envelope detectors to derive the estimated frequency information which carries auxiliary data information. It then uses this signal to produce estimated restored auxilia…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.