Siemens DataNET Hub (DNH) User Manual page 48

Signal Equalizer Settings for Non Recommended Cable or Unknown
Cable Lengths,
40 • • • • Installation
Continued
Step
3. Examine the recorded signal levels and determine the dB
loss for each port; refer to Table 2-2.
Example:
With these signal levels, port 4 is the lowest level, so no at-
tenuation is required. Its signal level becomes the reference
for comparing the remaining ports' signal levels.
The next strongest signal is on port 1.
This is within the 3-dB variance allowed, Use Selection 1 or 0
dB (ratio 1) setting.
The next strongest signal is on port 2.
Since 2.9 dB meets the 3 dB variance allowed, selection 2
can be used (3.5 dB loss), which will put the level at about 0.6
dB below the signal on port 4.
Next is the signal on port 8.
Since this signal is 11.1 dB stronger than the signal on port 4,
the attenuator board on port 8 needs to be set to selection 5
(11 dB loss). This should put its signal at about 0.1 dB above
the signal of port 4.
Action
20 log 1.28 = 2.1 dB
or
ratio of 1.28
20 log 1.4 = 2.9 dB
or
ratio of 1.4
4.5/1.25 = 3.6
20 log of 3.6 = 11.1 dB
or
ratio of 3.6
1.6/1.25 = 1.28
1.75/1.25 = 1.4
2000585-001