Comtech EF Data SDM-2020 - Manual (Page 51)

SDM-2020 Satellite Modulator Revision 7
Front Panel Operation MN/SDM2020M.IOM
5-9
5.6.1.2 C
ONFIGURATION
:M
ODULATOR
:TX-SR
TX-SR QPSK 7/8
15.000000 Msps
Selections include : QPSK 1/2, 3/4, 5/6, or 7/8
8PSK 2/3, 5/6 or 7/8
16QAM 3/4 or 7/8
Use this menu to program the modulator symbol rate (SR) from 1 to 37.5, in 1 sym/s
steps, limited by code rate and data interface.
Programming is done by either data rate or symbol rate. Data rate refers to the equivalent
serial data rate at the data interface connector.
Symbol rate refers to the modulation rate after framing, trellis (Viterbi) coding, and
Reed-Solomon coding are applied.
The framing type selection affects the symbol rate (if programming from the data rate
[TX-DR] menu), or the data rate (if programming from the symbol rate
[TX-SR] menu). If data rate is programmed, the symbol rate menu is updated to reflect
the code rate and framing selections. If symbol rate is programmed, the data rate display
is similarly updated.
1 Press while the menu is displayed to turn OFF TX-IF Output.
2 Press a second time while the menu is displayed to turn ON TX-IF OUTPUT.
3 Observe the on/off status of the TRANSMITTER LED.
On entry, the current symbol rate is displayed with the flashing cursor on the first character.
1 Press [ ←] or [→] to move the flashing cursor.
2 Press [ ↑] or [↓] to increase or decrease the digit at the flashing cursor.
3 Press [ENTER] to execute the change.