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P300H P300 Series Modem Installation and Operating Handbook Page 54
Tx: 1:Service 2:Baseband
3:Clocking 4:Modulator 5:ESC/Aux/BA
Change, Tx Menu
Tx Service: [IDR] 1=Off 2=Closed Network
3=IBS/SMS 4=IDR 5:Custom
Change, Tx/Rx, Service Menu
6.6 CHANGE, TX MENU
The Change, Tx menu is shown below. Note that options 2-5 are only displayed when the SERVICE option
is set to something other than `Off`, and so initially, the screen may only show the SERVICE option.
Taking each of these possible selections in turn:
6.6.1 Change, Tx/Rx, SERVICE Menu
The options are:
OFF This disables the path completely for Tx or Rx only operation. All alarms for that
path are muted, and traffic faults ignored. For the Tx path the Tx carrier is also
muted.
CLOSED NET The Tx/Rx path operates in a `Closed Network` mode. If the Async ESC feature
is available (standard P300-IBS and above) then a subsequent screen (described
in the next section) asks if it is normal Closed Network, or whether Closed Net
Plus ESC is required. Normal Closed Network adds no overhead to the data and
is compatible with other closed network equipment such as the Paradise P200,
and closed network equipment from other vendors.
Closed Net Plus ESC adds the lowest possible overhead to the satellite data to
provide whatever ESC rate is selected. When this mode is selected there is also
the option to provide a Backward Alarm facility. Closed Net Plus ESC also has the
advantage that at rates above 32kbps a synchronous scrambler is used (in place
of the error multiplying V.35 scrambler used on normal closed network links) and,
if used with Drop/Insert, the `Timeslot Identity is maintained`. If you want the
backward alarm, synchronous scrambler, or Timeslot ID Maintenance
advantages of Closed Net Plus ESC, but don’t want an ESC channel, simply
select the ESC to the lowest Baud rate available (50 Baud), and the rest of the
features will be provided within less than 0.5% overhead.
IBS/SMS The Tx/Rx path operates in IBS/SMS `Open Network` mode, where a 1/15th
framing overhead is added to the data. In this mode the Modem is compatible with
other `Open network` equipment such as the P230, P230D/I, OEM modems used
with a P1300 framing unit, or other `Open Network` equipment from other
vendors. Refer to the section "IBS/SMS Service Features" in Appendix F on page
207 for a full description of IBS/SMS features.
IDR The Tx path operates in IDR mode, where a 96kbps framing overhead is added
to the data. In this mode the equipment is compatible with OEM modems used
with a P1300 framing unit, or other `IDR` equipment from other vendors. Refer to
section "IDR Service Features" in Appendix F on page 213 for a full description
of IDR features.