ADC Telecommunications Inc. DVICSRIU800 用户手册
ADCP-75-114 • Issue C • June 2001
Page 19
©
2001, ADC Telecommunications, Inc.
5. Determine the total cable loss that is imposed by the coaxial cable that links the antenna
to
the RIU and by the forward path coaxial cable that links the RIU to the DHU.
6. Subtract the total cable loss from the total composite power calculated in step 4.
7. Subtract –20 (the composite maximum input signal level required at the DHU) from the
7. Subtract –20 (the composite maximum input signal level required at the DHU) from the
amount
determined in step 6. The difference equals the total amount of gain required to
raise
the forward path signal level to the –20 dBm level required by the DHU. The result
should
be negative which indicates that gain is required. The following formula outlines
the
required calculations:
P
tot
– CL
tot
– (–20) = Amount of gain (should be negative) required.
Where;
P
tot
is
the
total
composite power in dBm (step 4)
CL
tot
is the total cable loss (step 5)
–20
is the composite maximum input signal level required at the DHU
8. Using a small screwdriver, adjust the FWD LEVEL ADJ rotary switches to insert the
gain
required (as determined in step 7) to provide a –20 dBm signal at the DHU. Refer to
Figure
14 for a description of how the rotary switches work and to Table 4 for the
adjustment
settings.
Note: The RIU provides a forward path signal adjustment range of from +9 dB to +40 dB.
9. Disconnect the spectrum analyzer or power meter from the antenna.
9. Disconnect the spectrum analyzer or power meter from the antenna.
FWD LEVEL ADJ
MSB
LSB
0
0
16
2
4
6
8
10
12
14
REV LEVEL ADJ
MSB
LSB
0
0
16
2
4
6
8
10
12
14
INSERT A SMALL SCREWDRIVER INTO THE SLOT.
ROTATE THE SWITCH UNTIL THE WHITE ARROW IS
ALIGNED WITH THE REQUIRED SETTING.
ROTATE THE SWITCH UNTIL THE WHITE ARROW IS
ALIGNED WITH THE REQUIRED SETTING.
16649-A
Figure 14. Rotary Switch Adjustment