Method and apparatus for error detection and processing
US5251220A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 28, 1990 |
| Grant date | Oct 5, 1993 |
| Priority date | — |
| Expiry date | Nov 28, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/17363
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An Off-premises CATV system having an interdiction apparatus includes a remote microprocessor which receives commands and data from the headend over the cable distribution plant. The data is in a modified Manchester format (biphase-M) at 19.2 K baud which is then frequency modulated on a carrier of 108.2 MHz. A receiver detects the base band signal and outputs a serial digital signal to one input port pin of the microprocessor. The microprocessor rejects incorrect messages by measuring the duration between the negative transitions in the data signal. For those negative transitions which do not fall within predetermined windows where data transitions or a start of message character should be, an error is detected and the message is discarded.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.