121
2.048Mbps Wireless Modem
TECHNICAL: 0118 931 2233
The following table provide details on effective data rate and default modem rate for
Fractional E1/T1 applications. In general, effective data rate for N used channels is (N+1) x
64 Kbps. For example, if the user needs 8 channels, the modem will effectively transmit a
data rate of (8+1)*64 = 576Kbps. In fractional T1 applications, the modem will add a full
64Kbps channel for signalling. The maximal data rate of the modem for a 24 channel T1 is
therefore 1600Kbps, vs. the 1544Kbps of a regular T1. In Fractional E1using Common
Channel Signalling (CAS), as is also the case with a regular E1 using CAS, channel 0 is
always used for frame alignment signals, and a maximum of 31 channels is available to the
user, with a maximum data rate of 2048Kbps.
Table C-1. Channels Characteristic
The default modem rate for both regular T1 and regular E1 is 3Mbps. Therefore, an
improvement in achievable distance is available through using the Fractional E1/T1 LIU for
any number of channels up to 22.
Fractional E1/T1 Connections and Common Problems -Link
Set-up
The set-up includes two 2.048Mbps Wireless Modems, each connected to end equipment.
One end equipment unit is the source of the clock and is called CO (Central Office). The
other unit uses loopback timing (i.e. lock on the CO clock and return it) and is called PBX.
The modem connected to the CO is configured as Master, and the other modem as Slave.
Figure C-1. Fractional E1/T1 Application
