Web GUI Monitoring & Control
Figure 4.14: Signal Constellation Window
The image displayed above is that of the demodulated signal constellation. The displayed
constellation is 16APSK, at 13.5 M baud. When the demodulator is receiving an ACM or VCM
physical layer signal, the displayed constellation may be a composite of any of the modulation
types present, i.e. QPSK, 8PSK, 16APSK, 32APSK or pilots symbols (from dummy PL frames).
4.7.3.2.1
Number of Points
A drop-down box allows the user to choose the number of points to be used in the image, from
1024 points (default) to 8192 points in octave steps. This setting controls the density of the
displayed constellation.
4.7.3.2.2
Persistence
If the persistence box is checked, successive constellation images are superimposed upon each
other.
4.7.3.3
Equaliser Frequency Domain Response
To select the Equaliser Frequency Domain Response function:
1.
Select the fourth icon, in the row of seven. A window, similar to that displayed in Figure 4.15 is
displayed with the selected icon highlighted in blue.
Notes
1.
The equaliser frequency domain tool is only available when the equaliser is enabled. This is only
possible in DVB-2 modes.
2.
Outside of the region occupied by the wanted signal, the frequency response of the equaliser is
indeterminate and will vary in a dynamic fashion.
In this window, the extent of the frequency axis is once again equal to twice the symbol rate of
the demodulated signal.
SBD75e Series Demodulator Installation and Operation Manual
4-17