INSTALLATION & SET-UP
14
3 . 1. 1 Select RJ45/BNC
This single switch is used to select which type of connector is to be used to connect the E1
line.
3 . 1. 2 CRC4 and T/S 16 bypass
These two switches define whether CRC4 checking is to be done on the E1 line, and whether
T/Slot 16 is to be bypassed.
Figure 3.3 CRC4 & Timeslot options
3 . 1. 3 Framing
UNFRAMED
mode can be selected by setting the
BANDWIDTH
bit-switches to 0 (zero).
When this is done, the
START T/S
switches have no effect, and the unit remains in
UNFRAMED
mode.
In
G.704(no CRC4)
mode, TS0 is used to provide framing information. Bit 1 in TS0 is set to
1 and no data error checking occurs.
In
G.704(CRC4)
mode, TS0 is used to provide framing information and a Cyclic Redundancy
Check (CRC) is performed to test for data errors. Note that
FALLBACK
can occur from
G.704(CRC4)
mode.
Fallback is a mechanism used in a CRC4 environment which allows G.704 framing to be
maintained in the presence of high levels of CRC errors. In effect the receiver falls back to
G.704 (no CRC4)
mode. This allows traffic to pass from a CRC4 framed device to a non-
CRC4 device without generating a Loss of Frame alarm (LOF).
3 . 1. 4 Timeslot 16 by-pass & bandwidth
With Timeslot 16 by-pass
OFF
, TS16 may be used for payload. With by-pass
ON
, TS16 is
always left idle. Thus, if by-pass is O
N
and
START TIMESLOT
is set to 15 and
N
is set to 2,
then TS15 and TS17 are used and TS16 is by-passed.
CRC4
Comment
On (Enabled)
TS0 for framing info & CRC4 data integrity check on frame
Off (Disabled)
TS0 for framing info, no data integrity check on frame
By-pass
T/S16
No of payload
T/Slots
Bandwidth
nx64K
Comment
On
30 max
(n =1-30) x 64K TS16 by-passed for payload
Off
31 max
(n =1-31) x 64K TS16 can carry payload
