3-14 Bench Setup
SG 2000 Installation and Operation Manual
Launch Amplifier Output Stage Padding
By definition the launch amplifier is everything between the optical receiver RF output and the node
output connector. The launch amplifier output-stage pad-effects charts show the tradeoff, over a
range of output levels, between composite triple beat (CTB) and carrier-to-noise ratio (c/n) when
pads are inserted ahead of the individual output hybrids. It is assumed that the output of the link is
constant, so that the same amount of attenuation is removed from the pad facility at the receiver
output. The four pairs of curves, illustrated in Figures 3-8 and 3-9, are for pad values of 0, 3, 6, and
10 dB. An overall tilt of 12.5 dB is assumed for the 750 MHz model and 11.5 dB for the 870 MHz
model.
Figure 3-8
SG2-75 low-gain output-stage pad-effects chart
45.00
50.00
55.00
60.00
65.00
70.00
75.00
80.00
85.00
38 39 40 41 42 43 44 45 46 47 48 49 50
Output Level (Highest Analog), dBmV - 12.5 dB Tilt
CNR, dB
-85.00
-80.00
-75.00
-70.00
-65.00
-60.00
-55.00
-50.00
-45.00
CNR-10
CNR-6
CNR-3
CNR-0
CTB-0
CTB-3
CTB-6
CTB-10
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