User's Manual

Fiber Optics Powerwave

4 - 8 Rev. P1A9-Draft 2004-11 VM100 56/EN – User’s Manual

Uplink RF Signal Path

The uplink RF modulated signal path, from the repeater service antenna to the BTS, is

shown in Figure 4-5. The item numbers in the figure are described below. Item numbers

are omitted for those items that have the same function and settings as in the downlink

path.

Figure 4-5. Uplink RF transmission path

1. Repeater amplifier

The repeater amplifier is the same as the downlink amplifier, but in this case the output

power should be adjusted to match the FON input power range, 10 – 36dBm.

2. Power attenuator

The input 16dB/8W power attenuator is the same as the downlink amplifier, but in this

case an alternative configuration can be used.

In the alternative configuration a FON unit without this power attenuator is used. In this

case a lower output power from the FOR unit is fed directly to the following adjustable

attenuator.

The advantage of this configuration is less signal noise.

3. Software adjustable attenuator

The software adjustable 0 – 20dB attenuator is set manually via an O&M software. This

is described in the FON section of the VM100 01/EN, OM-Online, User’s Manual.

If the BTS has a larger coverage area than the repeater, then the attenuator is usually

adjusted to a total uplink gain to the BTS of –10dB (shown in the figure).

If the coverage area is the same for the BTS and the repeater, then the BTS antenna input

sensitivity with connected repeater should be the same as the sensitivity at the repeater

antenna input.

The total uplink gain can, however, not be set only on the software adjustable attenuator

but has to be balanced on the three uplink set points highlighted in Figure 4-6 (see the

next section).

FON

312

FOR

BMU

16dB, 8W

0 – 20dB

BMU

FON

BTS

–10dB