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QMultiFlex-400™ Installation and Operating Handbook
6.2.4.4 Tx Symbol Rate
Range:
0.1 Msps to 69.9 Msps; step size: 0.000001Msps (i.e. 1sps)
Description:
As an alternative to setting the terrestrial data rate, it is possible to set
the symbol rate for the satellite link, which will then determine the data
rate. Symbol rate entry is forced if using ACM.
In the absence of the user setting the symbol rate, it will be determined
by other settings such as the terrestrial data rate, modulation and FEC
rate.
6.2.4.5 Tx FEC Type
DVB-S2X
DVB-S2
6.2.4.6 Multiple Tx Streams
This is an On/Off checkbox that controls whether the DVBS2/DVBS2X transmit carrier
consists of multiple MODCOD streams.
Single stream mode allows a single MODCOD to be applied to the shared outbound carrier,
whereas with multiple streams, potentially different MODCODs can be applied to the
individual streams when they are transmitted over satellite in the shared outbound carrier.
This is a feature known as Variable Coding and Modulation (VCM). There is no change to
the overall symbol rate or power of the outbound carrier when the bandwidth is shared
between several different MODCODs. The streams are usually associated with one or more
VLANs in the QoS settings. Currently there is a limit of six MODCOD streams, which
translates into six remote areas with individual MODCODs.
The traffic shaping options differ between single stream and multiple streams. When the
shared outbound is represented by a single stream (i.e. single MODCOD) then the QoS
classification methods are VLAN IDs, IP addresses, Diffserv and IEEE 802.1p priority tags.
With multiple streams the only QoS classification method is VLAN ID.
When multiple streams are enabled then the single stream 'Tx Rate Control' and MODCOD
parameters (i.e., modulation, FEC rate, pilots and frame size) is disabled. Multiple streams
are configured in the 'Modcods' tab, described in Section 6.2.6.
Table 6-4 Tx Symbol Rate
This enables DVB-S2X operation, making all of the DVB-S2X
modulation and FEC rates available (from QPSK to 64APSK).
DVB-S2X is not available as an option when Mesh network mode
is selected.
This enables DVB-S2 operation (from QPSK to 32APSK).
Table 6-5 Tx FEC Type
6-13
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