Comtech EF Data SDM-650B - Manual (Page 124)

Operation SDM-650B Satellite Modem
4–22 Rev. 5
Assign RX_Fltrs
Demodulator symbol rate assignment. This function is used to view
current filter rate assignments, and to make filter rate re-assignments.
The demodulator 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 demodulator
installation, and when circumstances indicate the need to do so.
To view the current filter assignments, press [ENTER] when the Assign
RX_FLTRS selection is displayed from the Utility Functions menu. On
line 1 of the display will be RXA which indicates transmitter filter A.
Following RXA 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 (RXB, RXC, and RXD).
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
rates 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
demodulator 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 RXR in the
Configuration Functions menu.