Mer By Carrier (Cofdm); Graph Of Mer By Carrier (Cofdm) - Promax TV EXPLORER II Manual De Instrucciones

USER'S MANUAL. TV EXPLORER II/II+
5.17

MER by carrier (COFDM)

5.17.1 Graph of MER by carrier (COFDM)

This function analyses the MER for each of the carriers forming the selected
channel and displays it continuously in a graphic form.
It is a very useful measurement in order to analyze systems in which signals of
different types and sources interfere among them, as in the case of the transition from
analogue to digital TV.
In next figure a MER by carrier analysis for a COFDM 8k signal is performed.
40
30
20
10
MPEG-2 TS DVB-T
F: 634.00
As it shows in the following figure, when analysing MER by carrier in this digital
channel appears three degradation areas throughout the channel that make suspect the
presence of an underneath analogue channel.
Analog level
Video Carrier Colour
Subcarrier Subcarrier
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.
12/2013
MER BY CARRIER
1652 3718
AVG MER:
C: 41 STD DEV:
Figure 49.- MER by carrier function.
Frequency
Audio
Carrier
5784
27.4dB
3.2dB
MER
by carrier
Carrier
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