Promax MC-377+ Instruction Manual page 82

INSTRUCTION MANUAL MC-377+.
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-377+ 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-377+.
SDT power for Symbol Rate other than 27.500 MBauds
Power measurements made 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 1.1 dB subtracted from the reading obtained by the MC-377+.
Page 36
6.656250
5.705357
30.000
22.000
20.000
17.180
9.096
5.632
5.000
CORRECTION [dB]
- 1
- 2
CORRECTION [dB]
+0.5
-1.1
-1.3
-2.0
-2.6
-3.0
-3.1
May 2001