Comtech EF Data SDM-100A - Manual (Page 194)

Options SDM-100A Satellite Modem
B–12 Rev. 0
B.2 ADPCM Voice Interface
The ADPCM voice interface is capable of providing a single duplex voice channel and
Ear and Mouth (E&M) signaling data transmission. The interface also provides an EIA
STD RS-422 interface which is user selectable. This optional interface replaces the RS-
422, RS-232, or V.35 interfaces.
B.2.1 Theory of Operation
The ADPCM interface is designed to simulate either a trunk or a subscriber circuit.
(Refer to Figure B-2.) The E&M circuitry supports types 1 to 5. Trunk or Subscriber
configuration and E&M signaling type are user selectable from the front panel in the
CONFIG INTERFACE menu.
Refer to Figure B-3 for a modem block diagram with the ADPCM voice interface option.
Trunk
DMUX DMOD
MOD MUX
E & M
DMUX DMOD
MOD MUX
E & M SUB
M
E
M
E
SDM-100A
(Configured as a Subscriber.)
SDM-100A
(Configured as a Trunk.)
Figure B-2. System Interface Diagram