Browse Prior Art Database

Variable Threshold Error Correction

IP.com Disclosure Number: IPCOM000098089D
Original Publication Date: 1961-Dec-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Freiman, CV: AUTHOR

Abstract

Binary information is transmitted from sender 10 to receiver 11. The information transmitted includes code checking information. For example, the information may be transmitted in a 2-out-of-5 code. The signals which are received by receiver 11 are recorded in analog form. That is, the actual magnitude and waveforms of the signals which are received are recorded.

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Variable Threshold Error Correction

Binary information is transmitted from sender 10 to receiver 11. The information transmitted includes code checking information. For example, the information may be transmitted in a 2-out-of-5 code. The signals which are received by receiver 11 are recorded in analog form. That is, the actual magnitude and waveforms of the signals which are received are recorded.

The signals, as received, are first scanned with a prespecified threshold to determine the number and position of the 1's and 0's which are received. The resulting binary output is supplied to code checking circuit 13. If the code information does not check, for example, if each character is transmitted in a 2 out of 5 code, and circuit 13 does not find two 1's in a certain character, circuit 13 signals circuit 12. The latter re-scans the information using a different threshold. The binary information obtained by the re-scan is then sent to circuit 13. The threshold is changed and the information is re-scanned by circuit 12 until circuit 13 indicates that the code of the information, which was received, checks.

More complicated codes than a simple 2 out of 5 code can be used. For example, higher order fixed codes or separable sum codes can be used. The system is especially useful where the signal transmitting device has a limited power output.

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