Comtech EF Data SDM-309B - Manual (Page 169)

MN/U-SDMs09B Rev. # A–1
Appendix A.
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
board in place. See Figure A-1 for location of the hardware.
4. Remove the daughter card (0715) from the modulator. Figure A-3 and Figure A-
4 are fixed rate filter cards.
5. Install the replacement daughter card (0715) so that both screw holes line up.
See Figure A-1.
!
CAUTION
If the filter is installed in the wrong position, damage will result on
the daughter card.
6. Reinstall the daughter board hold down screws (Figure A-1) and reinsert the
modulator into the chassis.
7. Remove the demodulator card (0778) (white card ejectors).