Motorola SG 2000 用户手册
2 - 1 6 O v e r v i e w
SG 20 00 Ins tal la tion and O pera tion M anua l
Gain Selection
Figures 2-9 through 2-13 illustrate SG 2000 gain and tilt selection charts based on frequency and
channel load options.
channel load options.
To use the gain option selection charts, Figures 2-9 and 2-10, first find the point on the left hand axis
that corresponds to the expected optical input power at the node. Move across this horizontal line to
the right until it intersects a vertical line corresponding to the desired RF output level.
that corresponds to the expected optical input power at the node. Move across this horizontal line to
the right until it intersects a vertical line corresponding to the desired RF output level.
If this intersection is above and to the left of the diagonal “lo gain limit” line for the channel loading
under consideration, the low-gain option will give optimum performance with minimum padding. If
the intersection lies between the “lo gain limit” and “hi gain limit” lines, then choose the high-gain
option. Operation at a combination of input and output levels below and to the right of the “hi gain
limit” line is not possible.
under consideration, the low-gain option will give optimum performance with minimum padding. If
the intersection lies between the “lo gain limit” and “hi gain limit” lines, then choose the high-gain
option. Operation at a combination of input and output levels below and to the right of the “hi gain
limit” line is not possible.
Figure 2-9 illustrates the gain option selection chart for 750 MHz:
F i g u r e 2 - 9
O p t i c a l i n p u t v e r s u s 7 5 0 M H z g a i n
O p t i c a l i n p u t v e r s u s 7 5 0 M H z g a i n
-5
38
40
42
44
46
48
50
52
-3
-4
-2
-1
0
1
2
Bridger output level (dBmV), 750 MHz equivalent
(Trunk output level is 10 dB lower)
O
pt
ic
al
input
(
d
B
m)
Lo gain limit, 94 ch
Hi gain limit, 94 ch
Lo gain limit, 77 ch
Hi gain limit, 77 ch
Hi gain limit, 94 ch
Lo gain limit, 77 ch
Hi gain limit, 77 ch
750 MHz Gain Selection
Figure 2-9 gives the output level at 750 MHz. For a system loaded with analog channels to
550 MHz, the actual level at 550 MHz is 3.5 dB lower with the standard overall tilt of 12.5 dB. For
the low tilt of 10 dB, the reduction at 550 MHz is 3.0 dB. For the high tilt of 14 dB, the 550 MHz
level is 4.0 dB lower than at 750 MHz.
550 MHz, the actual level at 550 MHz is 3.5 dB lower with the standard overall tilt of 12.5 dB. For
the low tilt of 10 dB, the reduction at 550 MHz is 3.0 dB. For the high tilt of 14 dB, the 550 MHz
level is 4.0 dB lower than at 750 MHz.