User manual Multibox6T International
655603.03 rev A
Page 10
7.2.3.1
Reception
Use this menu to measure the reception quality of each
channel. There are two Reception sub menus, “Reception”
for Channel 1, 2 and 3 and “Reception 2” for Channel 4, 5
and 6. If these are not optimal the picture and sound
quality may deteriorate in poor reception conditions and it
may be necessary to adjust the aerial. The information
refers to the 4 installed muxes for the 6 channels.
The sub menu shows the channels numbers and frequencies
of the installed muxes. Good reception quality requires a
strong incoming signal. For more information on the
optimal signal strength see Chapter 8.2.3.2 Antenna Signal.
It may be necessary to adjust the aerial for optimal signal
strength. The signal quality C/N (Carrier to Noise) value is
a measurement of the relationship between the aerial
signal and disturbance in the channel. This should be higher
than 20 dB for a 64 QAM signal or 16 dB for a 16 QAM signal.
The BER (Bit Error Rate) measures the ratio of the number
of faulty bits received to the total number of bits received. The BER should be as low as
possible and less than 2.00E-4 (2*10
-4
) to ensure good quality picture and sound.
If all the parameters for the incoming signal are good but there are still problems with the
picture or sound quality it is likely that there is a problem with the cable that connects the
TV sets and VCRs to the Multibox.
7.2.3.2
Antenna quality
The Multibox has an inbuilt spectrum analyser. This shows
the level of the incoming signals on the UHF band (channels
21-69, 470-862 MHz). The picture to the right shows the
signal level of the incoming channels. The chosen muxes for
the installed channels are green. The recommended level
for the incoming channels is between 45 dB
μ
V and 75 dB
μ
V
(between the 2 red horizontal lines).
Check that the green columns are between the 2 red
horizontal lines. If not it may be necessary to adjust or
upgrade the TV aerial or to attenuate the incoming signal.
The red columns indicate the chosen output channels for the Multibox. If there are muxes in
the red columns you should change the output channel to another frequency (see chapter
8.2.2 Output channels).
