Monday, December 06, 2004

E1 Technology

Q: What's E1 exactly?What does it mean & how it works?Please explain in brief & complete.
A: E1 is the European equivalent to the American T1. Although both E1 and T1 use 64 kbps channels, they differ in many aspects. E1 is a point-to-point, dedicated, 2.048 Mbps communications circuit that carries 32 channels contrasted with T1's 24 channels. Of these 32 channels, 30 channels transmit voice and data. Unlike T1, E1 always provides clear channel 64 kbps channels.
Of the two remaining channels, one uses time slot 16 and is used for signaling and carrying line supervision (such as whether the telephones are on-hook or off-hook). The other remaining channel uses time slot 0, and is used for synchronization, channel control, and framing control.
There are two options for the physical media:
* 120 ohm twisted pair cabling, typically foil shielded. This is called a balanced interface and uses a DB-15 or 8-pin modular connector.
* 75 ohm coaxial cable. This is called an unbalanced interface because the two conductors do not have an equal impedance to ground, and uses a BNC connector.

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