Quantum and Evolution Series Installation and Operating Handbook
11-5
Differential Station Clock
This provides a RS422 compatible station clock in addition to the unbalanced 75
Ω
station
clock BNC connector.
Async Port for ESC or Aux Channels
The modem has two fully independent data channels that may be carried over the
satellite within any overhead that is added. These are referred to as the ESC and Aux
channels. The shared interface on this connector allows the use of only one of these
channels at a time, and then only in an Async mode (there is no clock signal on this port).
If both ESC and Aux channels are to be used together or either channel used in a
synchronous mode, then the IDR option must be fitted which provides separate ESC &
Aux ports both with clock, data, and octet lines. When the IDR option is fitted the shared
ESC/Aux port on the Async ESC connector is DISABLED.
When configured for different services the ESC and Aux channels provide as follows:
•
In
Closed Net Plus ESC
mode the ESC channel provides the variable rate async
ESC facility, the Aux channel is not used.
•
In
IBS/SMS
modes the ESC channel provides the High Rate Async ESC facility
(2400 Baud at 64kbps) and the Aux channel either the Intelsat low rate ESC facility
(50 Baud at 64kbps) or a variable rate synchronous Aux circuit. However to use the
Aux channel in a synchronous mode the IDR option must be fitted. Without the IDR
option that has separate ports for ESC & Aux channels, both ESC and Aux channels
(ie high rate async ESC & Intelsat low rate ESC) cannot be used simultaneously.
•
In
IDR
Mode this port is not used, as when the IDR option is fitted separate ESC and
Aux ports on the IDR card replace this shared ESC/Aux port. Refer to the definitions
of the ESC & Aux ports on the 50 way IDR ESC/Aux/Backward Alarm connector on
the following few pages.
Standard Lead
A constellation monitor/serial lead (part number M1479) is available from Paradise
Datacom. This lead provides the required connections to a 25 pin D type for a PC
connection (note that this is currently unused by the modem) and three BNCs for
connecting to an oscilloscope for the constellation monitor.
