Appendix A. Data Rates And Filters - Comtech EF Data SDM-309B Installation And Operation Manual

DATA RATES AND FILTERS
The SDM-309B modem will operate at data rates from 64 Kbps to 2.048 Mbps with
variable rate filters or fixed rate filters.
This appendix covers data rate change instructions for fixed rate and variable rate filters
in Section 1. It also covers the differences between a fixed rate filter in Section 2, and a
variable rate filter in Section 3, and describes the modem configuration for each filter
type.
1.0 Data Rate Change Instructions
1.1 Fixed Rate Filters
1. Turn off modem power switch.
2. Remove the modulator card (0773) (Black card ejectors).
3. With a phillips screwdriver, remove the two (2) screws holding the daughter
4. Remove the daughter card (0715) from the modulator. Figure A-3 and Figure A-
5. Install the replacement daughter card (0715) so that both screw holes line up.
6. Reinstall the daughter board hold down screws (Figure A-1) and reinsert the
7. Remove the demodulator card (0778) (white card ejectors).
MN/U-SDMs09B Rev. #
board in place. See Figure A-1 for location of the hardware.
4 are fixed rate filter cards.
See Figure A-1.
If the filter is installed in the wrong position, damage will result on
!
the daughter card.
CAUTION
modulator into the chassis.
Appendix A.
A–1