Comtech EF Data CDM-570 - Manual (Page 105)

CDM-570/570L Satellite Modem with Optional IP Module Revision 12
Front Panel Operation MN/CDM570L.IOM
5–19
While this submenu always displays the available options, the cursor will skip
past an unavailable choice.
Note the following:
Selection Description
Default-On The appropriate scrambler type is automatically selected
IESS-315-
On
This applies only when Turbo is installed and has been selected as the FEC type
Off No scrambling
The default scrambler types are:
Uncoded :
Viterbi, no framing:
Viterbi, EDMAC frame:
Viterbi + RS or TCM/RS:
TPC:
8-QAM TPC:
ITU V.35 (Intelsat variant)
ITU V.35 (Intelsat variant)
Comtech proprietary, frame synchronized
Per IESS-308, frame synchronized
Comtech proprietary, frame synchronized
ITU V.35 (Intelsat variant)
5.2.2.1.3.9 (CONFIG: Tx) Clk (Clock Source)
Tx Clocking Mode: Int
Ext Loop-Timed (◄ ►,ENT)
Use the
◄ ► arrow keys to select Int, Ext, or Loop-Timed, and then press ENTER.
Note the following:
Selection Description
Int
(Internal) Indicates that the CDM-570/570L will supply a clock to the DTE, which is derived from its
internal frequency reference. If the IP Module is installed and the selected Data Interface is IP,
then Internal is the only valid selection.
Ext
(External) Indicates that the CDM-570/570L expects to receive a clock from the DTE, to which the
modem 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.