Comtech EF Data RCF6001 - Manual (Page 28)

Maintenance RCF6001 Satellite Terminal
Page 4-8 TM082 - Rev. 1.0
Bit 1 - ES to ES Data Channel This bit is routed directly to the ES to ES Data Channel. Its data
rate is 1/512th of the aggregate rate (or 1/480
th of the through
terrestrial data rate), and is normally used to super-sample an
asynchronous data channel.
Bit 2 - Part of the Frame Alignment word.
Bit 3 - Backward Alarm Transmit and Receive with main processor to activate main
alarm/LED
Bit 4 - Multiframe Message As per IBS
Bits 5 and 6 - Spare Not currently utilized
Bits 7 and 8 - Encryption Utilization Not currently utilized
The ratio of the through terrestrial data channel rate to the aggregate rate is 15/16.
The standard transmit and receive channels of the ES to ES data channel in standard IBS mode are raw
channels operating at the specific bit rate as controlled by the data channel rate, without buffering. Also,
no clocks are provided with this channel. Since it would be rare that the data rate provided was exactly
that required for a standard rate device, the only method of communicating using this channel is to allow
it to super-sample the user data.
3.9 Asynchronous Multiplexer Mode
Since many of the frame bits in the standard IBS mode are not used, an "Enhanced" multiplexer mode
has been implemented that can be engaged under software control. Since this mode changes the use of
many of the framed non-data bits, this mode is only usable when the DMD2401 is at both ends of a link.
In this mode, the overhead signaling bytes 16 and 48 can be used to implement a significantly higher
speed ES to ES Data Channel under software control. When implemented, this rate is 16 times that of
the normal IBS standard, or 1/30
th
of the terrestrial data rate (1/32nd of the aggregate rate).
NOTE: The IBS (Async) mode MUST be selected for true Asynchronous channel operation to be available.