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AIMA3000.FT5S Product User Manual
Technetix Group Limited
•
technetix.com
May/2016 - Version 1.0
35
Example 3
This example will include a mix of analogue and QAM RF channels.
Sample channel load:
Analogue channels = 50
QAM64 channels = 13 at -10dB back off
QAM256 channels = 15 at -6dB back off
First step is to determine total RF power of the suggested channel load. This will require the QAM RF channels to be
calculated to analogue equivalent RF power. As the QAM RF channels operate -6dB and -10dB below the analogue RF
channels, the RF power of the QAM channels is significant less RF power compared to analogue channels.
Rule of thumb,
• 10 x QAM operating at -10dB from analogue channels equals same RF power of 1 x Analogue RF channel
Formula for calculating QAM RF to equivalent analogue RF power.
QAM RF equivalent power = (Nd) x 10
-(back off /10)
(Nd) = Number of QAM RF channels
Back off = RF delta between Analogue RF and QAM RF
Typically QAM64 operates at 10dB below analogue RF, QAM256 operates 6dB below analogue RF.
Calculating total RF power
13 x QAM64 at -10dB
QAM RF equivalent power = (Nd) x 10
–(back off /10)
QAM RF equivalent power = (13) x 10
–(10 /10)
QAM RF equivalent power = (13) x 0.1
QAM RF equivalent power = 1.3 x analogue channel
15 x QAM256 at -6dB
QAM RF equivalent power = (Nd) x 10
–(back off /10)
QAM RF equivalent power = (15) x 10
–(6 /10)
QAM RF equivalent power = (15) x 0.25
QAM RF equivalent power = 3.8 x analogue channel
Total RF power
50 channels analogue = 50 analogue equivalent
13 x QAM @ -10dB
= 1.3 analogue equivalent
15 x QAM256 @ -6dB = 3.8 analogue equivalent
Содержание AIMA3000.FT5S
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