Time domain supervisory channel for data terminal equipments
US4330858A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 29, 1979 |
| Grant date | May 18, 1982 |
| Priority date | — |
| Expiry date | Jun 29, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04J3/12
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
Digital data communication system uses a common channel to carry both normal messages and supervisory messages, the latter being inserted into the message stream during intervals between normal messages. Each transmitting location has a switch or equivalent controller with three settings. Setting 1 enables data to pass from the normal message generator directly to the channel. Setting 2 enables data to pass indirectly from the normal message generator through a delay line to the channel. Setting 3 enables data to pass from the supervisory message generator to the channel. Message status means associated with the delay line enables the switch to assume setting 3 when no normal message is being generated and a supervisory message is awaiting transmission. When the supervisory message ends, the switch may assume setting 1 if the delay line contains no significant normal message data nor any indication that an out-of-synchronism condition exists; otherwise the switch assumes setting 2 until the delay line is cleared of normal message data or reaches a synchronous state, as the case may be, whereupon it returns to setting 1. Each supervisory message has a distinctive format which enable…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.