Comtech EF Data SLM-7650 Installation And Operation Manual page 104

SLM-7650 Satellite Modem
Theory of Operation
4.4.3.2.1.8 IDR Overhead ESC
The interface option card provides access to the IDR engineering service channels at the
50 pin connector. IDR ESC requirements are defined within IESS-308 and IESS-403.
Characteristic
ESC Audio
ESC 64 kbps Data
ESC 8 kbps Data
ESC Backward Alarms
Demodulator Fault Relay
IDR Deferred
Maintenance Alarm
Requirement
2 duplex 32 kbps ADPCM channels
Audio encoding per CCITT G.721
Interface – 600Ω transformer balanced 4-wire
Audio output gain – programmable from -6.0 to +8.0 in 2.0 dB steps
Audio input gain – programmable from -6.0 to +8.0 in 2.0 dB steps
Replaces 32 kbps audio channels when enabled
Interface type – EIA422
ESC TX data is sampled on the rising edge of the ESC TX clock
sourced from the overhead card. The ESC TX clock will have a
period of 64 kHz and a duty cycle of approximately 50%.
ESC RX data and clock is sourced from the overhead card. Data
transitions occur on the falling edge of the clock. The clock period
will be 64 kHz and have a duty cycle of approximately 50%.
Interface type – EIA422
ESC TX data is sampled on the rising edge of the ESC TX clock
sourced from the overhead card. The ESC TX clock will have a
period of 8 kHz and a duty cycle of approximately 50%. In addition
the transmit interface provides an octet signal at 1 kHz for byte
alignment purposes.
ESC RX data and clock is sourced from the overhead card. Data
transitions occur on the falling edge of the clock. The clock period
will be 8 kHz and have a duty cycle of approximately 50%. In
addition the receive interface provides an octet signal at 1 kHz for
byte alignment purposes.
4 alarm inputs with 1 k Ω pull-ups to +5 Vdc. Pull input to ground to
clear alarm.
4 alarm outputs with Form C relays (NO, NC, and C contacts). The
alarm condition is indicated by a connection between the NO and C
contacts.
Form C relay with NO and C contacts available for backward alarm
inputs. Contacts NO and C are connected when no demodulator
fault is present.
Open collector output. Sources ground when alarm is not asserted.
Output rated 15 Vdc (max), 20 mA (max)
4–22
Revision 4
MN/SLM7650.IOM