Merogram - Promax TV EXPLORER HD User Manual

TV EXPLORER HD / HD
USER'S MANUAL.
Analog level
Video Carrier
MER by carrier
Figure 50.-
Scheme of interference due to TV analogue signal over a digital channel.
If we compare this graphic with the spectrum analyser of an analogue channel we
realise that in effect the video, audio and colour carriers affect more intensively the MER
of those digital multiplex located at the same frequencies. In this case, the COFDM
channel is strong enough to be affected by this interference.
This interference could not be detected in any other way for it can't be seen on the
spectrum analyser and it is not strong enough to degrade the average MER, CBER or
VBER readings substantially.

5.17.2 Merogram

The Merogram is an useful tool to detect sporadic problems on a period of time in
a DVB-H/T channel. It is specially designed to detect potential and sporadic problems
during time goes by.
The Merogram function makes a graphical representation of the MER level carriers
regards to the time. Each level is represented with a different colour, the Y-axis belongs
to carriers and the X-axis to time. Therefore a colour map is showed on the display, see
figure below.
Any MER level could be displayed at any time reference using cursors. This tool is
especially useful when a MER level analysis is going to be processed during a long
period of time. When the process is finished the capture could be showed and any
anomaly will be easily detected at any time.
Only DVB-T and DVB-H signals could be used with this function.
10/2012
LE
Frequency
Colour Audio
Subcarrier Subcarrier
Carrier
MER
by carrier
Carrier
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