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OM20 Universal Outdoor Modem
It is not mandatory to assign timeslots in sequential order, although the
lowest timeslot must be entered in the lowest channel. For example:
timeslots may be assigned 1 - 2, 2 - 5, etc. but not 1 - 5, 2 - 2.
E.7
Configuring the OM20 for Drop and Insert
Several dependencies exist when configuring the modem for Drop and Insert (D&I). The
following paragraphs explain these dependencies and provide the user with the information
required to ensure smooth transition into D&I and to minimize the potential impact of these
dependencies.
E.7.1 Data Rate
Data Rate affects the Drop and Insert function in the following ways:
•
It determines the number of Satellite Channels that will be displayed in the Edit Maps.
•
It contributes to the Operational Mode selection process. Trying to change the Operational
Mode to D&I when a data rate is not set to a valid D&I rate will result in the error message
'INVALID DATA RATE,' and the mode change will not be allowed.
•
It contributes to the Terrestrial Framing Mode selection process. Trying to select a T1-type
Drop Mode such as T1-ESF with the mod data rate set to 1920000 bps (a valid E1 D&I rate
but not a valid T1 rate) will result in the error message 'INVALID DROP MODE' and the
selection will not be allowed. Trying to select a T1 type Insert Mode such as T1-D4 with the
demod data rate set to 1920000 bps will result in the error message INVALID INSERT
MODE and the selection will not be allowed.
•
Once D&I Mode has been selected, trying to change the data rate to something other than
another valid D&I data rate will result in the error message 'RATE OUT OF BOUNDS' and
the change will not be allowed.
•
Once D&I Mode has been selected with a T1 Terrestrial Framing Mode, attempting to
change the data rate to 1920000 will result in the error message 'RATE OUT OF BOUNDS'
and the change will not be allowed.
Therefore, after the interface type, the data rate should be entered as the first step in configuring
the modem for D&I. The Mod Data Rate should be set according to the number of timeslots to
be dropped and the Demod Data Rate should be set according to the number of timeslots to be
inserted. The following table gives the allowable D&I data rates based on the number of slots (n)
to be dropped or inserted.
MN-OM20– Revision 5
Appendix E
E–7
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