Measuring Ber Of Qam Digital Channels (Qam) - Promax PROLINK-3 Premium Manual De Instrucciones

4.9.1.5.1 Measuring BER of QAM Digital Channels (QAM)

Press the rotary selector to access the QAM signals parameters that must be
defined by user and that are described below:
1) Modulations
It defines the modulation type. When selecting this function and pressing the
rotary selector a multiple-choice menu will appear on the screen, this menu
permits to choose one of the following modulations: 16, 32, 64, 128 and 256.
2) Symbol Rate
When selecting this function and pressing the rotary selector a multiple-choice
menu will appear on the screen, this menu permits to choose one of the following
values: 6900, 6875, 6111, 5000, 4443, 1528, 1500, 1408, 1333, 1266, 1000
kbauds, or well to define any other value by means of the Other option.
When selecting the Other option, a screen titled QAM SYMBOL RATE will appear,
this screen shows present Symbol Rate value, to modify it press key
enter the new value (four figures) and finally press the rotary selector to activate it.
3) Spectral Inv.
If necessary, activate the Spectral inversion. If the spectral inversion is not
correctly selected, reception will not be correct.
4) Attenuator
It permits to select attenuation between 0 and 30 dB. It is advisable to activate the
30 dB attenuator under that measurement conditions where the signal level is
near to the maximum input level (approximately starting from 20 dB under the
maximum level) and it is possible that the tuner becomes saturated. Under no-
saturation conditions, when increasing the attenuation value the BER measure
must to maintain or to increase (insufficient signal level) but never to decrease.
In case of doubt, you must consider that the correct attenuator setting (0 to 30 dB)
will be that corresponds to the best BER measurement (value more low).
Once you have defined the QAM signal parameters, it will be possible to measure
the BER.
When the BER measuring mode is selected, the monitor will show a picture like
the following:
Only for models with this option available
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USER'S MANUAL. PROLINK-3/3C Premium
[31],
06/2005