User Manual Part 2

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Initial Prism System Setup

Page 174 FlexWave Prism Host, Remote and EMS 5.1 System Reference

FWD/REV path signal and the other DART will be configured

Diversity

. This

selection therefore determines whether the DART card being configured will

carry the primary or secondary RF path.

For dual DART configurations, such as dual-pcs, smr800/smr900 and

dual-aws, both DARTs must have

DART Diversity Status

set to

nonDiversity

gg 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

+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.

hh In the

DART Forward Delay

box, set in microseconds the actual delay that will be

applied to the RF forward path signal. The minimum delay required is

calculated. The acceptable range of delays is 88us. If you attempt to set the

delay to a value outside the allowed range, the DART uses either the minimum

or maximum, dependant on whether the DART is exceeding the set delay (too

high or low).

Be aware of simulcast links. Observe the minimum delay required for the

longest link, and set the delay to the same value for all simulcast nodes in the

same connection based on this value.

Here is an example:

•• Fiber has 8 usec per mile of fiber.

•• Remote 1 has 5 miles of fiber (40 usec of fiber delay).

•• Remote 2 has 10 miles of fiber (80 usec of fiber delay).

The diversity status, fiber, and timeslots of the Host DART must match the Remote

DART linked to it.

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.