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QMultiFlex-400™ Installation and Operating Handbook
6.2.28.2 Modulator alternate 1,0
With this enabled - an alternating 1,0,1,0 pattern is fed to the modulator at the selected
symbol rate. This causes two discrete frequencies to be generated, spaced at the symbol
rate about the center frequency (suppressed carrier). This is useful for evaluating the
carrier suppression of the modulator but should not be used over a live satellite link.
6.2.28.3 Packet BERT
The 'Packet BERT' is a bit error tester that uses PRBS patterns formatted into IP packets
which can be encapsulated and used with DVBS2/DVBS2X services. This useful tool can
help determinie the performance of the outbound carrier path or an inbound carrier path
(limited for use with one demodulator).
Figure 6-74 Test Screen
To enable the BERT to replace terrestrial traffic with PRBS pattern packets – select
'Generate Packets to Tx Sat' in the drop down menu.
At the other end of the link – the Rx BERT analyser should be set to 'Analyze Rx Datapath'
Inject error will inject a single error into the datastream. This is useful to test data
transparency.
Reset will re-start the BERT results. Once the Rx BERT Analyser is enabled – it is worth
reseting the results page to clear any previous data and reset the Events/Rx errors to zero.
The BERT will display the average BER result, the Rx Errors, the bits received, any loss of
sync events, the RTT (only valid if in an RF loopback) and the Elapsed test time from the
last 'Reset'.
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