User`s guide

3-12 DL600E E1 Data Multiplexer UserÕs Guide
and the CRC values are compared. If they do not match, the
frame is considered bad and the
CRC statistic is incremented.
Line ImpedanceÑ75 OHM (BNC) or 120 OHM (DA15) (DefaultÑ
75 OHM)
Appears in Menu-4 only when the remote unit is a DL600E unit.
The
Line Impedance can be 75 OHMÑBNC unbalanced or 120
OHMÑDB15
balanced.
Main/Alt SyncÑINT, EXT[n], NET, and DATA [1] (DTE)
(DefaultÑNET/INT)
Select the E1 network transmitterÕs clock source. First specify
the
Main clock source, then the Alternate. (Each clock source has
the same options.) Type
y to conÞrm each action.
The DL600E unit always attempts to use the Main clock source. If
it is not available (due to a missing signal from the source or a
diagnostic test), it uses the
Alternate source.
Select
NETWORK if the network is the clock source. If it is not,
select
INTERNAL at one E1 end, and NETWORK at the other. Select
DATA if the DTE is the clock source. If the DL600E unit is the
DTE device, use a cable appropriate to your application. When
neither the
Main nor Alternate clock source is available, the DL600E
unit uses
INTERNAL.
During all full bandwidth pattern tests, the DL600E unit cannot
use
NETWORK timing. Typically, the remote unit is in network
loopback during a test and the DL600E unit should not use
NETWORK timing since the received network signal is the signal
it is generating. In this case,
NETWORK is overridden and
Alternate (if available) or INTERNAL is used.
The clock currently in use appears on the screen in upper case letters.
In the example in Figure
3-2, the local main and alternate clock in
use is
INT while the remote main clock is NET (the alternate clock,
int, is not in use)
.
In-Band Communications BitÑ4 to 8 (DefaultÑ4)
Select a national bit (from 4 to 8) in timeslot 0 for the in-band
4Kbps communications link with the remote unit. Digital Link
proprietary messages are sent to the remote unit using this bit.
G.704 recommends using bit 4. (The unused national bits are set
to 1.) If this feature is disabled, all national bits are set to 1.