Promax US TV EXPLORER II, User Manual

Page: 74 / 268

USER’S MANUAL. US TV EXPLORER II
Page 66 01/2008
The US TV EXPLORER II also includes, a ZOOM function to enlarge graphic
representation over one single quadrant. Select the SCROLL option to move the focus
over the whole viewing area using arrow cursors [6] key, CLEAR option to reset
the graph screen or SHARP option to increase the image clearness over a range from 0
(minimum visual persistence) to 16 (maximum visual persistence).
NOTE
The transmission quality is visualized in a qualitative way using a colour range for
the symbol density concentrated in a certain area. This colour coding goes from
black (no symbols) to red (maximum density), and runs from blue to yelllow in
ascending order.
A greater dispersion of the symbols indicates greater level of noise or worse signal
quality.
If concentration of symbols or noise appears is indicative of good carrier/noise ratio
or absence of problems as phase noise, etc.,.
5.15.2 DVB-C (QAM) signal
Sets on the UTILITIES menu by pressing the [22] key, and select the
CONSTELLATION option.
On screen appears the modulation type: DVB-C ( 256 QAM ). Also the frequency
and channel number are indicated. Finally, it shows the type of DVB-C broadcast
network used.
Figure 46.- Constellation diagram. DVB-C ( QAM 256 ) signal.