Apparatus and method for reducing multiplicative gain variation distortions in data recording and transmission channels
US3940694A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 26, 1974 |
| Grant date | Feb 24, 1976 |
| Priority date | — |
| Expiry date | Jun 26, 1994 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B20/1496
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Data channel gain-variation distortions are reduced by the following combination of operations. Successively occurring data items are cumulatively added in modulo fashion thereby providing a sequence of partial sums. An exponentiating circuit is introduced to provide an exponential function of the partial sums. The exponentiated partial sums are then recorded or transmitted on a data channel wherein the signals are distorted by relatively slow gain variations thereof. The received distorted signals are applied to a logarithmic circuit wherein the multiplicative gain variation distortions are converted to additive distortions. The logarithmically converted signals are applied to a subtractor that sequentially provides the differences in modulo fashion between successively occurring signals from the logarithmic circuit thereby yielding the data items with the distortions substantially reduced.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.