Comtech EF Data CDM-570 - Manual (Page 98)

CDM-570/570L Satellite Modem with Optional IP Module Revision 12
Front Panel Operation MN/CDM570L.IOM
5–12
Press ENTER to continue through all configurations. Press CLEAR to discontinue.
5.2.2.1.3 CONFIG: Tx (Transmit)
Tx:FEC Mod Code Data Frq
On/Off Pwr Scram Clk Inv
Use the
◄ ► arrow keys to select FEC, Mod, Code, Data, Frq, On/Off, Pwr, Scram, Clk, or Inv,
and then press ENTER.
The submenu selections are summarized as follows:
Selection Sect. Description
FEC 5.2.2.1.3.1
(Forward Error Correction) Used to select the method of FEC used for transmission
(Viterbi, TPC, etc). FEC type takes the highest configuration priority.
Mod 5.2.2.1.3.2
(Modulation) Used to select the modulation type used for transmission (BPSK, QPSK,
8-PSK, etc.). The choice of modulation will depend on the FEC type chosen.
Code 5.2.2.1.3.3
(FEC Code Rate) Used to select the FEC Code Rate used for transmission (Rate 1/2,
Rate 3/4, etc.). The choice of Code Rate will depend on both the FEC type and
Modulation selected.
Data 5.2.2.1.3.4
(Data Rate) Used to select the transmit data rate, in steps of 1 bps. The choice of data
rate will depend on the FEC type, Modulation, and Code Rate selected.
Frq 5.2.2.1.3.5
(Frequency) Used to select the transmit frequency, in steps of 100Hz.
CDM-570L range: 950 MHz to 2000 MHz
CDM-570 range: 50 to 90 MHz and 100 to 180 MHz
On/Off 5.2.2.1.3.6 Used to control the output state of the transmit carrier.
Pwr 5.2.2.1.3.7
(Output Power level) Used to control the output level of transmit carrier, either
manually, or using the AUPC (Automatic Uplink Power Control) feature.
Scram 5.2.2.1.3.8
(Scrambler) Used to select whether or not data scrambling is used.
Clk 5.2.2.1.3.9
(Clock Source) Used to select the clock source for transmission. This can be from the
CDM-570L’s high stability internal source, from an external source, or from the distant-
end of the satellite link (loop timed).
Inv 5.2.2.1.3.10
(Inversion) Used to invert the sense of the transmitted spectrum, or to invert the sense
of the transmitted baseband data.
VERY IMPORTANT NOTE: The FEC type takes the highest configuration
priority, and the selection here depends on what, if any, optional plug-in
codecs are installed. The choice of FEC type then determines what modulation
types, code rates, and data rates are available. The order of hierarchy is
therefore:
FEC type (Highest) ► Modulation type ► Code Rate ► Data Rate (Lowest)
If a parameter is changed within this hierarchy, the other parameters may become
invalid. In this case, the software will change those other parameters, in order that
the configuration remains valid at all times.
Example: Suppose you select Viterbi + Reed-Solomon, QPSK, Rate 1/2. Now, you