This contains the following options:
• IDR 8k ESC mode. This controls the operating mode of the low-rate IDR ESC
channel, which can be set to Off, Synchronous or Asynchronous.
• ESC interface baud rate. IBS uses a fixed frame format and therefore the amount
of overhead is limited. The maximum ESC baud rate that may be selected is
displayed.
• ESC interface character length. This can be set to 7 or 8 bits.
• ESC interface parity polarity. This can be set to None, Even or Odd.
• IDR ESC audio data encoding. This controls audio data format for the ESC
overhead in IDR mode. The overhead can be set to 32, 64 or 96kbps. 64kbps of
this can be not transmitted, allocated to voice or allocated to Aux data via the Aux
controls. When set to Off, V1 and V2 are omitted and consequently only 32kbps
overhead is transmitted (or the 64kbps of V1 and V2 overhead can be reallocated
to Aux data via the IDR Aux mode setting). The 32kbps overhead includes FAS,
backward alarms and an 8kbps synchronous ESC channel. When set to 2x16k in
V1, two 16kbps ADPCM channels are provided in V1 (with V2 either being omitted
or being replaced with Aux data as determined by the IDR Aux mode setting).
When set to 1x32k in V1, 32kbps is provided in V1 (with V2 either being omitted or
being replaced with Aux data as determined by the IDR Aux mode setting). When
set to 2x32k in V1,V2, the normal full 96kbps of IDR overhead is used, including
two audio ESC channels encoded as 32kbps ADPCM, as well as the standard
32kbps for FAS, backward alarms and an 8kbps synchronous ESC channel .
• IDR Aux data. This controls the Aux channel in IDR mode. It allocates Aux data in
place of one or both of the IDR voice channels if these are not used or can be
used to reduce the 96kbps overhead to 64kbps or 32kbps. When set to Off, no
Aux data is placed in the overhead. When set to 32K, 32kbps of Aux data
replaces the data in IDR audio ESC channel V2 (this requires the IDR audio mode
setting to be 2x16k in V1 or 1x32k in V1). When set to 64K, 64kbps of Aux data
replaces the data in IDR audio ESC channels V1 and V2 (this requires the IDR
audio mode to be set to Off).
• ESC level ch1, ch2. These can be set in the range 0 to 38dB. They set the
input/output levels for the IDR audio ESC channels. The two channels can be
configured independently.
• Backward alarm mode. This controls routing of multiple backward alarms in IDR
mode. When internally linked from Rx-Fail to BA1 or BA1-4, these alarms respond
similarly to the normal single backward alarm. The options are to set
o Backward alarm 1-4 external
o Backward alarm 1 internal, backward alarm 2-4 external
o Backward alarm 1 internal, backward alarm 2-4 forced okay
o Backward alarm 1-4 internal.
• ESC interface type. This specifies which of the modem’s physical interfaces is to
be connected through to the satellite ESC channel. This is described under the
Edit->Tx-Rx>Framing->Overhead Closed screen description.
• Aux interface type. This specifies the Aux electrical interface. The relevant
physical interface (on the shared Async ESC/Aux port on the base modem or the
separate Aux port on the IDR card) is directly connected through to the ESC
channel. This interface on the modem provides the IBS low-rate Intelsat
oversampled ESC facility. The ESC and Aux functions are mutually exclusive
unless an IDR card is fitted. If an IDR card is fitted then the Aux port can provide
32kbps or 64kbps access to the IDR overhead in place of one or both of the IDR
32kbps ADPCM audio ESC channels, or it can provide either the IBS low-rate
Intelsat oversampled ESC facility or a higher rate synchronous channel within the
IBS overhead.
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