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TPS in lock
The TPS (Transmission Parameter Signalling) are decoded. The TPS are
carriers (17 in the 2k system and 68 in the 8k system) modulated in DBPSK,
containing information related to the transmission, modulation and codification:
Modulation type (QPSK, 16-QAM, 64-QAM), Hierarchy, Guard Interval, Viterbi
Code Rate, Transmission mode (2k or 8k) and Number of the received frame.
MPEG-2
Correct detection of a MPEG-2 signal.
In case of detecting a DVB signal, message MPEG-2 DVB-T will appear and
the DVB Channels Identifier function will be automatically activated. (See section
'4.9.2 DVB Channels Identifier: DCI function').
DVB-T channels tuning may require an adjusting process. It is recommended to follow
next procedure:
1.- From the spectrum analyser mode, tune the channel at its central
frequency.
2.- Switch to TV mode, BER measuring mode.
3.- If in the lower line of the screen does not appear MPEG-2 message (and
consequently BER is unacceptable), by turning the rotary selector deviate
the tuning frequency until MPEG-2 message appears. Finally tune channel
again to minimize the frequency deviation which optimizes the BER and
therefore minimize the BER.
If it is not possible to detect any MPEG-2 channel, make sure that digital signal
parameters are correctly defined and if signal level is too low, check that the 30 dB
attenuator is not activated (Attenuator 0 dB).
4.9.1.5.3
Measuring BER of QPSK Digital Channels (QPSK)
Press the rotary selector to access the QPSK signals parameters that must be
defined by user and that are described below:
1)
Symbol Rate
It is possible to choose between the following values : 30000, 27500, 22000,
20000, 19995, 6110, 6000, 5998, 5632, 5062, 4340, 4000 kbauds, or well to
define any other value (Other).
When selecting the Other option, a screen titled QPSK SYMBOL RATE will
appear. This screen shows present value, to modify it press key
enter the new value through the keyboard. The unit accepts any number with 5
figures between 2000 and 35000 kbauds (fifth figure acts as validation). For
example, to select a symbol rate of 8200 kbauds it must be entered : 08200.
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USER'S MANUAL. PROLINK-4
IMPORTANT REMARK
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02/2003
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