Motorola SG 2000 operation manual Gain Selection, Optical input versus 750 MHz gain

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Gain Selection

Figures 2-9 through 2-13 illustrate SG 2000 gain and tilt selection charts based on frequency and 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.

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.

Figure 2-9 illustrates the gain option selection chart for 750 MHz:

Figure 2-9

Optical input versus 750 MHz gain

750 MHz Gain Selection

Optical input (dBm)

2

1

0

-1

-2

-3

-4

-5

38 40 42 44 46 48 50 52

Bridger output level (dBmV), 750 MHz equivalent

(Trunk output level is 10 dB lower)

Lo gain limit, 94 ch

Hi gain limit, 94 ch

Lo gain limit, 77 ch

Hi gain limit, 77 ch

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.

SG 2000 Installation and O peration Manual