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CDM-Qx Satellite Modem
Front Panel Operation
5.7.1.2
(Config%Tx) - TRANSMIT
Tx: FEC Mod
On/Off Pwr Scram Clk Inv Txα
Select FEC, Mod, Code, Data, Freq, On/Off, Pwr, Scram, Clk, Inv, or Tx
the ◄ ► arrow keys, then press
submenu. Each of these choices is described briefly in the following table:
FEC
Mod
Code
Data
Freq
On/Off
Pwr
Scram
Clk
Inv
Txα
IMPORTANT
Code
(Forward Error Correction) This submenu permits the user to select the method of
FEC used for transmission (Viterbi, TPC, etc). FEC type takes the highest
configuration priority.
(Modulation) This submenu permits the user to select the modulation type used for
transmission (BPSK, QPSK, 8-PSK, etc.). The available choice of modulation will
depend on the FEC type chosen.
(FEC Code Rate) This submenu permits the user to select the FEC Code Rate used
for transmission (Rate 1/2, Rate 3/4, etc). The available choice of Code Rate will
depend on both the FEC type and Modulation type selected.
(Data Rate) This submenu permits the user to select the transmit data rate, in steps of
1 bps. The choice of data rate will depend on the FEC type, Modulation type, and
Code Rate selected.
(Frequency) This submenu permits the user to select the transmit frequency, from
950 MHz to 1950 MHz, in steps of 100Hz for L-Band units, or from 50 MHz to 90 MHz
and from 100 MHz to 180 MHz for 70/140MHz units.
This submenu permits the user to control the output state of the transmit carrier.
(Output Power level) This submenu permits the user to control the output level of
transmit carrier, either manually, or using the AUPC (Automatic Uplink Power Control)
feature.
(Scrambler) This submenu permits the user to select whether or not data scrambling
is used.
(Clock Source) This submenu permits the user to select the clock source for
transmission. This can be from the internal source, from an external source, or from
the distant-end of the satellite link (loop timed).
(Inversion) This submenu permits the user to invert the sense of the transmitted
spectrum, or to invert the sense of the transmitted baseband data or data clock
(α-Factor) This permits the user to select the modulator's roll-off factor either 20% or 35%.
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 ► Modulation type ► Code Rate ► Data Rate
(Highest)
5–13
Data
Freq
. The user will then be taken to a further
ENTER
Revision 6
MN/CDMQx.IOM
α
using
(Lowest)
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