Stream Enable; Stream Modulation; Stream Fec Code Rate; Stream Frame Size - Teledyne QMultiFlex-400 Installation And Operating Handbook

Mcpc/scpc hub

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QMultiFlex-400™ Installation and Operating Handbook

6.2.6.1 Stream Enable

This is an On/Off control that controls whether a particular stream forms part of the shared

outbound or not. When enabled, all packets associated with the relevant stream will form

part of the shared outbound.

When all streams are disabled, then the contents of the shared outbound is determined

purely by the output of the traffic shaper, if enabled. When the traffic shaper is not used

then all received packets will be transmitted up to the limit of the available bandwidth and

thereafter will be dropped at random (subject to the IP buffer settings in the modem).

Each stream transmitted within the shared outbound carrier can use any of the supported

DVB-S2/S2X MODCODs listed in Table 6-6.

Each stream can use any of the supported DVB-S2/S2X code rates listed in Table 6-6.

The stream frame size is used in connection with DVB-S2/S2X.

Normal

Short

Pilots are an On/Off option that controls whether or not DVB-S2/S2X pilots, which are

unmodulated symbols, are injected into the carrier on a regular basis in order to help the

demodulator lock onto the carrier. The pilots are 36 symbols long and are injected every

1440 symbols, representing an additional overhead of around 2.4%.

This represents a frame size of 64,800 bits per frame. This is more

bandwidth efficient than short frames but has four times the

latency. As a guideline, short frames have a latency of around

25ms at 1Mbps, whereas the latency for normal frames is around

100ms at 1Mbps. The latency will halve as data rate doubles.

This represents a frame size of 16,200 bits per frame.

Table 6-18 Stream Frame Size

6-23

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