Overview of CE3 Interfaces
Introduction
In the 1960s, pulse code modulation (PCM) technology allows time division multiplexing (TDM) technology to be widely applied in the digital communication system. Two TDM systems are available in the digital communication system: E1 system recommended by International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) and T1 system recommended by American National Standards Institute (ANSI). The E1 system is widely used in European countries and China. The T1 system is widely used in Northern America and Japan (Japan uses JI that is similar to T1 and included in T1).
E3 and E1 belong to the same ITU-T digital carrier wave system. E3 supports 34.368 Mbit/s data transmission rate and high density bipolar of order 3 code (HDB3) line encoding and decoding format.
A CE3 interface is a physical interface in the E3 system, which can work in E3 mode (unchannelized mode). In E3 mode, a CE3 interface works at a rate of 34.368 Mbit/s without timeslot division. Similar to a synchronous serial interface, a CE3 interface supports IP network protocol and data link layer protocols such as PPP and frame relay (FR).
Clock Mode
To exchange data correctly, communicating parties must have their clocks synchronized.
- Master clock mode (using internal clock signals): In this clock mode, a CE3 interface uses the local clock generated by the chip as the reference clock.
- Slave clock mode (using line clock signals): In this clock mode, a CE3 interface uses the line clock as the reference clock.
Generally, the interface at one end of a link works in master clock mode, and the interface at the other end works in slave clock mode.