Q-Flex Satellite Modem Installation and Operating Handbook
6-11
6.2.4.2 Rx Values Track Tx
This is an On/Off control that allows the receive path to be automatically configured to be
the same as the transmit path, thereby simplifying set up. There are a number of
exceptions including carrier frequency, spectral inversion, timeslots and clock settings.
6.2.4.3 Tx/Rx Service
Off
This switches the modem’s Tx service off.
Closed network
Unlike open network services,
Closed network
in general
does not add any satellite framing overhead. However, some
framing overhead will be added for packetized data such as
IP, in order to allow the demodulator to synchronize with the
transmitted packets.
Closed network plus ESC
This provides a framed satellite service that incorporates an
Engineering Service Channel (ESC). The ESC provides a
secondary communications channel, often used for monitor
and control of remote equipment. The variable-rate ESC
channel can provide up to 70% of the main channel rate,
subject to a maximum size of 115kbps. It also provides a
backward alarm facility that notifies upstream equipment of
faults detected by downstream equipment.
Closed network
plus ESC
allows individual timeslots to be processed when
using the G.703 interface.
IBS
Intelsat Business Service (IBS) is an open network standard
where 1/15 framing overhead is added to the data. This
mode is compatible with other open network equipment.
IDR
Intermediate Data Rate (IDR) is an open network standard
that adds 96kbps of framing overhead to the data. This
mode is compatible with other open network equipment. It
requires an IDR option card to be fitted to the modem.
DVB-S2
DVB-S2 services can be used with both packetized and
continuous data streams. DVB-S2 requires a hardware
option card to be fitted to the modem.
For continuous data streams, such as G.703,
Closed
network
or
Closed network plus ESC
should be selected
together with
SmartLink
as the FEC type.
SmartLink
provides a DVB-S2 service along with all of the necessary
support for continuous data streams.
For packetized data, such as IP, it is normally sufficient just
to select the DVB-S2 service itself. Alternatively, should