Paradise P300 specifications Backward Alarm? =Normal 2=No Backward Alarm facility, Min O/H

INTELSAT V.35. This results in an increase in the error rate, as the V.35 scrambler multiplies any errors on the channel by a factor of three.

Both options lead on to the following question:

Backward Alarm:[?]

1=Normal 2=No Backward Alarm facility

Change, Tx/Rx, Service, Custom, IBS, Backward Alarm Menu

NORMAL A Backward Alarm is sent (Tx) or detected (Rx) as normal

NO BACK' ALM No Backward Alarm is sent (Tx) or received (Rx). This is a very useful facility to have to lose, but for maximum ESC operation this selection does free up one further bit of the overhead (TS32 bit 3) to carry ESC information.

If both the TS32 Multiframe and Backward Alarm options have been selected as Normal, then the following screen is displayed. If either the Backward Alarm facility or the TS32 Multiframe have been disabled, then this menu is skipped.

IBS Backward Alarm: [?]

1=Normal (single) 2=Four independent alarms

Change, Tx/Rx, Service, Custom, IBS, Back' Alm mode Menu

NORMAL A single backward alarm operates as normal

FOUR ALARMS The modem transmits or receives four independent backward alarms, using the form `c` outputs and backward alarm inputs normally used for IDR operation. This allows a single IBS Tx carrier feeding multiple Rx sites (each site receiving part of the data in the Tx carrier), to individually indicate to each site a failure of the return carriers from those sites. The sequence in which these four alarms are carried in the IBS overhead may be changed under Change, User-Opt,

Operation, Satellite, Back’ Alm Map.

Finally, all paths through these menus arrive at the following question:

Overhead Mode: [?]

1=Normal 2=Min o/h to provide set ESC

Change, Tx/Rx, Service, Custom, IBS, Overhead Mode Menu

This final option is the most powerful of the features in Custom IBS.

NORMAL	The standard 16/15 (6.7%) IBS/SMS overhead is used. The ESC rate available
	is a fixed proportion of the main data rate (but may be manipulated within limits
	by allocating more or less of the overhead to the ESC). When the ESC Baud rate
	is set too high, a warning will be displayed if the overhead cannot provide the
	requested ESC rate.
MIN O/H	The overhead varies to provide the ESC Baud rate set on the ESC menus.
	The following two examples explain typical scenarios:
	At 2048 kbps with a 9600 Baud ESC channel the overhead can reduce to
	less than 1% whilst still maintaining the IBS/SMS benefits (namely a factor of
P300H	P300'Series Modem Installation and Operating Handbook	Page 134