Carrier terminal unit
US4230911A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 28, 1978 |
| Grant date | Oct 28, 1980 |
| Priority date | — |
| Expiry date | Aug 28, 1998 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L25/05
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A carrier terminal unit for interfacing 1.544 MHz PCM lines to a digital switch, wherein voice samples are switched at 2.048 MHz, provides bit synchronization, in-frame monitoring, delay equalization and correction, framing detection, and rate and format conversion. A common memory is utilized for the delay equalization and correction, framing detection and rate and format conversion functions. The memory acts as an elastic store for delay equalization. Delay correction is provided by monitoring the relative positions of the memory read and write addresses and initializing the write addresses after an overtaking of the read or write addresses by the other is detected. Rate and format conversion are provided by storing incoming PCM samples in the memory and reading the samples out in accordance with a predetermined sequence. Framing detection is provided by storing in memory every nth bit of three alternate frames of incoming data. Subsequently, every nth incoming bit is compared with the corresponding bit stored in memory four frames earlier to determine if the predetermined pattern exists. A signal indicating the results of the comparison is also stored in memory. The stored indic…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.