Collision detection using code rule violations of the Manchester code
US5162791A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 2, 1989 |
| Grant date | Nov 10, 1992 |
| Priority date | — |
| Expiry date | Oct 2, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L25/4904
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A collision detection method and apparatus is disclosed for detecting code rule violations in Manchester encoded data packets. The signals EQU .delta..sub.0 =S.sub.2n -S.sub.2n-1 EQU .delta..sub.1 =S.sub.2n+1 -S.sub.2n EQU .delta..sub.2 =S.sub.2n+1 -S.sub.2n-1 EQU .sigma..sub.0 =S.sub.2n +S.sub.2n-1. are determined at time nT where S.sub.2n-1 and S.sub.2n are the Manchester code bit pair representative of the nth bit in a data stream having a bit period T. Processing of these signals permits the detection of most collisions since the Manchester coding rules are violated more than half the time in the signal formed by the colliding packets. To ensure 100% collision detection, a preamble using an intentional violation of the Manchester code in the pattern 10 11 01 10 is advantageously used in each data packet and a collision is signaled upon detection of two or more coding violations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.