Measuring Tho Power Of Digital Channels - Promax MC-577 Manuel D'utilisation

MEASURING THE POWER OF DIGITAL CHANNELS
As we have already mentioned, digital signals distribute their energy uniformly
across the entire bandwidth of the channel , therefore measuring the power of digital
channels depends on the channel Bandwidth or the Symbol Rate (the other
modulation parameters do not affect this measurement).
The MC-577 gives power measurements for digital channels under the precision
specified for terrestrial signals of a bandwidth of 7.607 MHz and for satellite signals
of a bandwidth corresponding to a Symbol Rate of 27.500 MBauds. Measurements
on channels made with characteristics different from these should be manually
corrected as described below .
TDT power for bandwidths other than 7.6 MHz
Terrestrial digital channels can have bandwidths of 7.607 / 6.65 / or 5.70 MHz
depending on the channelling in each country (these bandwidths correspond to a
channel separation of 8, 7 and 6 MHz respectively).
Power measurements made on terrestrial digital channels with a Bandwidth other
than 7.607 MHz should be corrected according to the following table.
BANDWIDTH [MHz]
Therefore, for example, the power measurement of a digital channel of 6.65 MHz should
have 1 dB subtracted from the reading obtained by the MC-577 .
SDT power for Symbol Rate other than 27.500 MBauds
Power measurements taken on satellite digital channels with a Symbol Rate other
than 27.500 MBauds should be corrected according to the following table.
SYMBOL RATE [MBauds]
Therefore, for example, the power measurement of a digital channel of 22.000 MBauds
should have 1.0 dB subtracted from the measurement obtained by the MC-577 .
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CORRECTION [dB]
6.656250
5.705357
30.000
27.500
22.000
20.000
17.180
9.096
5.632
5.000
USER'S MANUAL MC-577.
- 1
- 2
CORRECTION [dB]
+0.5
0
-1.0
-1.5
-2.2
-5.0
-8.0
-8.5
05/2003