INSTALLATION & SET-UP
15
3 . 1. 5 Setting Up Start T/S and Bandwidth
The 5 binary switches for
START TIMESLOT
and
BANDWIDTH
permit numbers from 0-31
to be set-up. The decimal values of each switch are shown on the label.
Thus, a
START T/S
of 11 and a
BANDWIDTH
of 4 would be set up as below.
Figure 3.4 Binary set-up
Permitted
BANDWIDTH
values are 1-30 with Bypass
ON
and 1-31 with Bypass
OFF.
3 . 1. 6 Timing
TIMING
is set by two bit-switches and determines the source for the LINE E1 transmit clock,
the V.35/X.21 Transmit timing and the V.35/X.21 Receive timing
.
The options are as follows:
INT (internal oscillator)
LOOP (E1 loop timing)
TERM (Terminal, i.e V.35/X.21 transmit is supplied by terminal device), or
DTE MODE (where the terminal device supplies timing for both directions of
transmission)
Note that when using TERM or DTE MODE, the terminal supplied clock must be accurate to
within
50 ppm of the Nx64K value. If the DTE clock is out of specification the E1 transmitter
will free-run at 2
048 MHz.
The recommended timing mode for the DC3X00 pair at either side of an E1 circuit (which is
not supplying timing), is
Internal
at one end of the link and
Loop
at the other end.
However, there are many other potentially valid timing mode combinations for a pair of
DC3X00 units, and it is important to ensure that the terminal equipment timing modes also
form part of the overall network design.
Start T/S
Bandwidth
01011
00100
