Mocomtech CDM-QX - Manual (Page 85)

CDM-Qx/QxL Multi-Channel Satellite Modem with DoubleTalk™ Carrier-in-Carrier® Revision 7
Front Panel Operation MN/CDMQX.IOM
5–19
5.4.2.8 CONFIG: Tx
Æ Scram
Scrambling: Default-On
IESS-315-On Off (◄ ►,ENT)
To set the Transmit Scrambling mode, select Default-On, IESS-315-On, or Off using the ◄ ►
arrow keys, then press
ENTER
. Note the following:
Default-On The appropriate scrambler type is automatically selected
IESS-315-On This only applies when Turbo is installed and has been selected as the FEC type
Off No scrambling
Scrambler Selection Notes:
1. If CnC is enabled, the V.35 scrambler is always used in order to suppress framing
artifacts.
2. As noted previously, all options are displayed all of the time, but the ◄ ► arrow keys
will force the cursor to skip past an unavailable choice.
The default scrambler types are as follows:
Viterbi, no framing:
ITU V.35 (Intelsat variant)
Viterbi, EDMAC frame: Comtech proprietary, frame synchronized
Viterbi + R-S or TCM/R-S: Per IESS-308, frame synchronized
TPC: Comtech proprietary, frame synchronized
CnC: ITU V.35 (Intelsat variant) – overrides other settings
5.4.2.9 CONFIG: Tx
Æ Clk
Tx Clocking Mode: Int Ext
Loop-Timed ExtLoop (◄ ►,ENT)
To set the Transmit Clocking Source, select Int, Ext, Loop-Timed , or ExtLoop using the ◄ ►
arrow keys, then press
ENTER
. Note the following:
Int
(Internal) Indicates that the CDM-QX will supply a clock to the DTE, which is derived
from its internal high-stability source.
Ext
(External ) Indicates that the CDM-QX expects to receive a clock from the DTE, to
which the unit can phase-lock its internal circuits. (If G.703 is selected as the Interface
type, the software will force the clock mode to External.)
Loop-Timed
Indicates that the transmit timing source should be the receive clock, from the
direction of the satellite. This is a useful mode, in that no external connection needs
to be made in this mode. If the demodulator loses lock, or if there is no receive signal
present, the internal clock is substituted. Note also that this mode will work even with
asymmetric Rx and Tx data rates.
ExtLoop
(External Loop) Indicates that the CDM-Qx expects to receive a clock from the DTE,
which is derived from the received clock from the direction of the satellite. This is
useful in CnC mode with G.703 interface wherein the remote station is relying on a
centralized clock from the hub station.
IMPORTANT