Comtech EF Data SDM-650B - Manual (Page 123)

SDM-650B Satellite Modem Operation
Rev. 5 4–21
Assign TX_Fltrs
Modulator symbol rate assignment. This function is used to view
current filter rate assignments, and to make filter rate re-assignments.
The modulator has four symbol rate filters. Filters are designated as A,
B, C, and D. Each filter is for a specific symbol rate. The data rate and
code rate for each filter must be established upon initial modulator
installation, and when circumstances indicate the need to do so.
To view the current filter assignments, press [ENTER] when the
Assign TX_FLTRS selection is displayed from the Utility Functions
menu. On line 1 of the display will be TXA, which indicates transmitter
filter A. Following TXA on line 1 will be the coder rate (1/2, 3/4, 7/8, or
BP12). On line 2 will be the data rate assigned to filter A. Use [
← ] and
[ → ] to see the assignments for filters B, C, and D (TXB, TXC, and
TXD).
To change a filter assignment, press [ENTER] when the data for that
filter is displayed. Use [
← ] and [ → ] until the flashing cursor is at the
parameter to be changed. Then use [ ↑ ] and [ ↓ ] to change that
parameter. When all changes are made, press [ENTER] to confirm the
assignment. Variable rate filters can only be programmed up to
2048 kbit/s. If a higher data rate is needed, use a fixed rate filter card.
Refer to Appendix A for more information on data rate changes and
variable rate filters.
Fixed rate filter cards can have from one to four pre-defined fixed code
and data rates installed on the filter card. If NA appears in the first line
after the transmit filter assignment, then the filter card on the modulator
does not have a filter present for that designated filter. These
assignments in the Utility menu must match the data rate on the filter
card, and cannot be changed unless the filter card is changed.
Note: These assignments are used for the selection of TXR in the
Configuration Functions menu.