IKUSI 2844 - Technical Annex

49
Technical annex
Output level reduction in broadband amplifiers
BROADBAND TERRESTRIAL TV AMPLIFIERS : The RF output levels specied in this
catalogue for IMD3=-60 dB (DIN 45004 B) are applicable when 2 analog TV channels are
amplied. If, as is usual, more than 2 TV channels are amplied, such levels have to be
reduced according to the following table:
Number of
Channels (n)
2 3 4 5 6 7 8 9 10 15 20
Output level
reduction
= 7,5 · log (n-1)
dB 0 2 3,5 4,5 5 5,5 6 6,5 7 8,5 9,5
FM, DAB AND COFDM SIGNALS : If output levels of the FM, DAB and Digital TV (COFDM) signals are
adjusted 10 dB or more below the levels of the analog TV channels, those signals can be ignored when
calculating the output reduction level. If referred levels are not reduced as indicated, those signals must
be counted as normal channels and the output level de-rated accordingly.
BROADBAND SATELLITE TV OR DIGITAL TERRESTRIAL TV AMPLIFIERS : The RF
output levels specied in this catalogue for IMD3=-35 dB (EN 50083-3) are applicable when
1 FM-, QPSK- or COFDM-modulated TV channel is amplied. For a bigger number of chan-
nels, such levels have to be reduced according to the following table:
Number of
Channels (n)
2 3 4 5 6 7 8 9 10 15 20
Output level
reduction
= 10 · log n
dB 3 4,5 6 7 8 8,5 9 9,5 10 11,5
13
CASCADE REDUCTION : When m same-type broadband ampliers are laid out in cascade, an additio-
nal reduction of the output level equals 10 · log m must be taken into account for every amplier.
EN