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P300H P300 Series Modem Installation and Operating Handbook Page 133
Custom framing based on: [?]
1=IBS 2=IDR
Change, Tx/Rx, Service, Custom Menu
Multiframe: [?]
1=Normal 2=Without a TS 32 Multiframe
Change, Tx/Rx, Service, Custom, IBS, Multiframe Menu
7 MENU SCREENS FOR SPECIALIST OPTIONS
The following sets of menu definitions are shown in this separate section in order not to complicate the
earlier section dealing with basic menu operation.
7.1 CUSTOM FRAMING MENUS
These features are only available if the `Custom Features` feature is available together with the
corresponding IBS or IDR options (standard on P300-TCM). Refer also to the section Closed Network
Plus ESC via the Custom Service menu in section 8.7.2 on page 148.
7.1.1 Change, Tx/Rx, Service, CUSTOM Menu
If Custom is select from the Change, Tx/Rx, Service menu, this leads to the following dialogue:
IBS This leads to variants on standard IBS framing (all explained later) which allow for
operation:
Without a TS32 multiframe
Without a backward alarm
With four backward alarms for Multidestinational IBS
Minimum overhead mode, where the overhead scales to provide any
ESC requirement at any data rate.
IDR This leads to variants on standard IDR framing (again explained later) which allow
for operation:
With overheads of 96, 64, or only 32 kbps.
With 16kbps ADPCM on the audio channels instead of 32kbps, allowing
either all normal IDR features in a 64 kbps overhead, or (again utilising
16kbps ADPCM) 96 kbps overhead with all normal IDR features, but
including a 32kbps spare channel for continuous BER traffic quality
monitoring.
The discussion of IDR this continues after the IBS section in para 7.1.3 on
page 135.
7.1.2 Change, Tx/Rx, Service, Custom, IBS Menu
If IBS is select from the menu above this leads to the following question:
NORMAL A TS32 Multiframe is used as normal.
NO TS32 MF No TS32 Multiframe is sent (Tx) or acquired (Rx). This is primarily for operation
at low rates where the TS32 multiframe becomes long enough to affect
acquisition time. For example at 32kbps the multiframe lasts 1 second, and hence
TS32 MF acquisition may take 1 second on top of demod lock time. This selection
also frees up one additional bit of the overhead (TS32 bit 4) to carry ESC
information.
The disadvantage of operating without a TS32 Multiframe is that the synchronous
IBS scrambler cannot be used, and the `Normal` scrambler option selects