Config, Tx) Pwr (Power); Config, Tx) Scram (Scrambling); Config, Tx) Clk (Clocking); Config, Tx) Tsi (Transmit Spectral Invert) - Comtech EF Data CDM-500 Installation And Operation Manual

CDM-500 Closed Network Satellite Modem
6.5.7

(CONFIG, TX) PWR (Power)

EDIT OUTPUT POWER LEVEL:
-03.9 dBm (PRESS ENTER)
Edit the output power level, over the range 0 to -20 dBm, by selecting the digit to be
edited, using the LEFT/RIGHT arrow keys). Change the value of the digit using the
UP/DOWN arrow keys. Press ENTER.
6.5.8

(CONFIG, TX) SCRAM (Scrambling)

SELECT TX SCRAMBLING:
OFF ON (PRESS ENTER)
Select ON or OFF, using the LEFT/RIGHT arrow keys, then press ENTER. When
Transparent mode is selected, a V.35 scrambler is used. In Framed mode, a frame
synchronised scrambler is used.
6.5.9

(CONFIG, TX) CLK (Clocking)

SELECT TX CLOCKING MODE:
INT EXT LOOP-TIMED (ENT)
Select either INT (Internal), EXT (External) or LOOP-TIMED, using the LEFT/RIGHT
arrow keys, then press ENTER.
INTERNAL indicates that the CDM-500 will supply a clock to the DTE, which is
derived from its internal high-stability source.
EXTERNAL indicates that the CDM-500 expects to receive a clock from the DTE, to
which the unit can phase-lock its internal circuits.
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.
6.5.10

(CONFIG, TX) TSI (Transmit Spectral Invert)

SELECT TRANSMIT SPECTRAL
INVERSION: OFF ON(ENTER)
Select OFF or ON, using the LEFT/RIGHT arrow keys, then press ENTER. When in the
ON position, and QPSK is selected, the transmit spectrum is inverted (which is the same
as reversing the direction of phase rotation in the modulator). In BPSK, the time-order of
bits out of the FEC encoder is reversed, to make the modem compatible with certain other
Rev. 1.3
Front Panel Operation
6–7