Automatic threshold adjustment circuit for digital data communication
US4847865A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 18, 1987 |
| Grant date | Jul 11, 1989 |
| Priority date | — |
| Expiry date | May 18, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B10/695
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An improved threshold circuit (30) for reconstructing digitally-encoded, optically-transmitted signals is disclosed. The threshold circuit (30) automatically compensates for amplitude variations in the received signal due to noise, gain variations, and the like, and thereby provides improved accuracy in reproduction of the digitally-encoded signal. An amplifier (120) generates an output signal the level of which, under low signal amplitude, is linearly related to the instantaneous level of the digitally-encoded input signal. An active low pass linear filter (122, 124, 132) generates from the amplified output signal a signal the level of which corresponds to the average level of the amplified output signal. A bias signal generator (40) receives the average level signal on one input and a selected reference signal on the other. The bias generator (40) outputs a bias signal the level and polarity of which are related to the degree and polarity of difference between the average level signal and the reference signal. The bias signal biases the linear amplifier (120) to compensate for any variations of the average level of the amplified input signal from a selected threshold value that c…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.