Comtech EF Data SDM-300L3 - Manual (Page 154)

SDM-300L3 Satellite Modem Revision 1
Front Panel Operation MN/SDM300L3.IOM
4–86
FUNCTION SELECT: UTILITY: MODULATOR: TX TERMINAL LO
TX TERMINAL LO
0 MHz MIX:-
Valid selections entered into this menu make it possible to directly program the
frequency transmitted from the satellite terminal using the Configuration: Modulator:
Terminal Frequency menu. The combination of the LO and MIX determine the terminal
frequency displayed. (When the terminal frequency mode is active, the actual TX L-Band
frequency is displayed under the Function Select: Monitor menu.)
Utility Modulator TX Terminal LO Menu
LO MIX Configuration: Modulator Menu (Effect On)
0 + or - The TX IF Frequency menu appears and the modem is programmed
over the L-Band range of frequencies.
3000 - 65000 + The TX Terminal Frequency menu appears and the modem is
programmed:
TX Terminal Frequency = LO + L-Band Frequency
3000 - 65000 - The TX Terminal Frequency menu appears and the modem is
programmed :
TX Terminal Frequency = LO – L-Band Frequency
The sign of the Mix, + or -, is determined as follows:
Mix = “+” when LO < terminal (satellite) operating frequency of the ODU or BUC.
Mix = “-“ when LO > terminal (satellite) operating frequency of the ODU or BUC.
Examples:
LO = 4900 MHz Mix = “+”
TX Terminal Frequency (Max) = 4900 + 1750 = 6650 MHz
TX Terminal Frequency (Min) = 4900 + 950 = 5850 MHz
LO = 15450 MHz Mix = “-“
TX Terminal Frequency (Max) = 15450 - 950 = 14500 MHz
TX Terminal Frequency (Min) = 15450 - 1750 = 13700 MHz