
P300H
P300 Modem Installation and Operating Handbook
Page 52
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
195 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 201 for a full description
of IDR features.