User's Manual

Initial Prism System Setup
Page 154 FlexWave Prism Host, Remote and EMS 5.1 System Reference
© 2009 ADC Telecommunications, Inc ADCP-77-073 • Issue 2 • 11/2009
For dual DART configurations, such as dual-pcs, smr800/smr900 and
dual-aws, both DARTs must have
DART Diversity Status
set to
nonDiversity
.
ee In the
DART Forward Gain
list, set this value (0 to 31 dB) based upon the fully
loaded forward path signal level from the Base Station. The Host DART expects
signal levels from
-25
to
+5 dBm
. If the fully loaded signal is +5 dBm, then the
DART forward gain should be set to 0 dB, if the fully loaded signal is -25 dBm,
then the DART Forward Gain should be set to 30 dB. The equation is:
DART Forward Gain = 5 - fullyLoadedBasestationSignal.
ff Set the
DART Reverse Gain
value to achieve the required gain from the input to
the Remote to the output of the Host DART. The range is:
•
5
to
36 dB
for Cellular, SMR800, SMR900, Narrowband PCS & Narrowband
AWS DARTs
•
0
to
31 dB
for Fullband GSM1800, UMTS, Fullband AWS, and EGSM900
The diversity status of the Host DART will extend to the Remote DART connected to it.
For further inf
ormation, see “Link the Host and Remote DARTs.” on page 159.
If you are setting up the system when no calls are going through, you must allow
headroom for a fully
loaded forward path. For CDMA protocols, the difference from
unloaded to fully loaded is typically 8
dB, so if the unloaded signal is - 15dBm, then the
fully loaded input would be - 7 dBm and the Host For
ward Gain should be set to 5- (- 7)
= 12 dB.
The same rules applies for GSM carriers, except that the u
nloaded to loaded is
determined by the equation 10*log10(# RF Channels). So if there are 4 GSM RF Cha
nnels,
then the loaded forward path is 6 dB above unloaded.
If sufficient headroom is not present, the
n the LPA can be over- powered causing a Loss
Of Service.
When configured correctly, the Host DART Forward input can handle peaks of 14dB
above the BTS signal
level. For example, if the fully loaded CDMA carrier is - 25dBm, then
peaks up to - 11 dBm can be handl
ed (CDMA peak to average is typically 10- 12 dB). If
the peaks exceed the 14 dB of headroom, then Auto
matic Level Control (ALC) will occur
to prevent over- driving the A/D Converter.