MDS 05-2415A01, Rev. A A-1
APPENDIX A—1200 BPS BELL 202T
COMPATIBLE MODEM
Optional System Equipment
Assembly P/N: 03-1815A01
INTRODUCTION
The 03-1815A01 modulator/demodulator (modem) was designed specifically for use with the
MDS 4300 Series Transceivers, allowing it to be mounted within the transceiver housing into
Option 1 jacks—J6 and J8. Figure A-1 shows an assembly drawing of the 1200 bps modem.
This modem is compatible with the Bell 202T standard and is normally used for a 1200 bit-
per-second (bps) data rate. It will track input data rates as low 50 bps. With this option
mounted within the transceiver enclosure, the MDS 4310 Transceiver can still be pro-
grammed through the RS-232 connector, without the need to remove the housing cover.
J8J6
Figure A-1. 1200 bps Modem PC Board
SPECIFICATIONS
Current Drain: 20 mA from the primary power source
Tone Frequencies: Mark: 1200 Hz, adjustable
Space: 2200 Hz, adjustable
Data Rates: 50–1200 bps Asynchronous
ALIGNMENT
Chapter 4—Field Tests and Adjustments contains alignment procedures for radios equipped
with 1200 bps modems. The modem alignment consists of setting the Mark tone frequency
(R2), Space tone frequency (R3), and the Receive Data Threshold (R25).
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