2017-01-27 | Technical changes, design modifications, errors and misprints are subject to change without prior notice.
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3.5.
Initialization phase 3
In phase 3, the modulators are configured.
The output channels are compulsory assigned to adjacent channels.
3.5.1.
Configuration of the modulator
The first modulator can be set to any output channel between S2 and CH 87. The other three modulators are
automatically set by incrementing the output.
For example:
modulator
1
=
Channel
21
modulators 2, 3 and 4 = Channels 22, 23 and 24
Output channels and
channel spacing
According to the BG standard, the special channels S2 to S20 and channels 5 to 12
in the VHF range have a bandwidth of 7 MHz. However, a higher bandwidth
allows more data to be transmitted. This is why in the frequency range in question
110...300 MHz channels are also available in the 8 MHz channel spacing. These
channels are D1 to D24 with a bandwidth of 8 MHz.The upper special channel
range and the UHF channels, likewise with a bandwidth of 8 MHz, follow D24
without a gap. The UHF range has been extended by channels CH70-CH87.
However, when using this range, you have to check whether all receivers support
the frequencies above 862 MHz.
DVB-C modulation:
With DVB-C modulation, you can choose between 32QAM, 64QAM, 128QAM and
256QAM. 256QAM enables the highest data transmission rate, but it also requires
the best network quality.
DVB-C symbol rate:
The DVB-C symbol rate can be freely set between 1000 and 7500. The standard
value is 6900. Some networks also work with 6875. When working with a
bandwidth of 7 MHz, 6111 is customary.
Output level / Level
setting
The
Output Level
options include attenuation and deactivation of the modulator.
Each of the four modulators is set separately. The max. output level of approx. 100
dBµV is reached with an
Output Level
setting of 20 dB.
Vernier adjustment:
The vernier adjustment of the output channel is performed in 0.5 MHz steps.
