Optical FSK demodulator
US4887314A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 16, 1989 |
| Grant date | Dec 12, 1989 |
| Priority date | — |
| Expiry date | Feb 16, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/14
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An optical demodulator in which a local oscillator reference signal and a frequency shift keyed modulated input signal are optically combined by means of an optical multiport junction. These signals are detected to produce phase-diverse electrical signals at beat frequency and electrically processed to provide a demodulated signal. The electrical processing circuitry is phase discriminating and thus produces a signal in which the amplitude is dependent upon the lead/lag phase relationship of the detected signals. The local oscillator is tuned to, and maintained at, a frequency that is midway between the FSK signal tones so that the lead or lag of phase is directly related to the frequency shift coding. The phase discriminant signal processing may be performed using envelope detection.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.