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3.2.2 System Configuration
The System Configuration menu looks like this:
The System Configuration options are described below:
Line Format: G.703
(default)
Options: G.703, G.704
G.703: G.703 is unframed, 2.048Mb/s. In this case, the DTE rate
is equal to the line rate at the network interface (NI). CAS MF
and CRC-4 are disabled.
G.704: G.704 reserves TS0 for signaling and frame alignment.
Maximum data rate depends on whether CAS MF is enabled
or not.
15 16
Line Coding: HDB3
(default)
Options: AMI, HDB3
HDB3: In this line coding, the transmitter substitutes a deliberate
bipolar violation when excessive zeros in the data stream are
detected. The receiver recognizes these special violations and
decodes them as zeros. This method enables the network to
meet minimum pulse density requirements. Unless AMI is
required in your application, HDB3 should be used whenever
possible.
AMI: Alternate Mark Inversion defines a pulse as a "mark,” a
binary one, as opposed to a zero. In a E1 network connection,
signals are transmitted as a sequence of ones and zeros.
Ones are sent as pulses, and zeros are sent as spaces, i.e.,
no pulse. Every other pulse is inverted from the previous
pulse in polarity, so that the signal can be effectively transmit-
ted. This means, however, that a long sequence of zeros in
the data stream will cause problems, since the NTU receiving
the signal relies on the signal to recover the 2.048 Mb/s clock.
If you must use AMI, you should ensure that the data terminal
equipment connected to the unit provides a minimally accept-
able pulse density. For this reason, there are advantages to
using HDB3 instead.
a
b