User's Manual

ADCP-75-187 • Preliminary Issue 1B • November 2005 • Section 3: OPERATION

Page 3-13

7. Calculate the total composite signal power using the following formula:

tot

= P

+ 10Log N

Where,

tot

is the total composite power in dBm

is the power per carrier in dBm as measured in step 6, and

N is the total number of channels.

8. Record the result measured in step 5 or calculated in step 7.

9. Place the AC circuit breaker switch (at the RU power panel) in the open (OFF) position.

10. Disconnect the spectrum analyzer or RF power meter from the HU ANTENNA port.

11. Re-connect the antenna cable to the HU ANTENNA port.

12. Place the AC circuit breaker switch (at the RU power panel) in the closed (ON) position.

2.5 Reference Procedure: Enter Remote Forward Attenuation

The RU internal forward path attenuator setting is used to reduce the power level of the

composite output signals at the RU. The maximum composite output signal level at the RU

antenna port is set using both the HU forward attenuator (see Section 2.3) and the RU forward

attenuator. Component variations may result in the output power at the HU antenna port being

slightly above or below the calculated value. The RU forward attenuator is used in conjunction

with the HU forward attenuator to add or remove attenuation to produce the required output

signal level at the antenna port. The default setting for the RU forward attenuator is 31 dB. Use

the following procedure to change the RU forward attenuation:

1. Click on the REMOTE RF tab. The REMOTE RF display will open within the EMS main

window as shown in Figure 3-9.

2. Check the level of the RF output signal (as determined in Section 2.4) against the system

design plan specifications. The maximum output signal level permitted is 38.1 dBm (6.5

Watts) for both 800 MHz and 800/1900 MHz SMR systems; and 38.3 dBm (6.7 Watts) for

1900 MHz systems.

3. Determine if more or less attenuation is required to produce the required output signal level.

4. Click on the Remote Fwd Att field Edit button (see Figure 3-9). The Remote Fwd Att

pop-up screen will open as shown in Figure 3-10.

Note: To comply with Maximum Permissible Exposure (MPE) requirements, the

maximum composite output from the antenna cannot exceed 1000 Watts EIRP and the

antenna must be permanently installed in a fixed location that provides at least 6 meters

(20 feet) of separation from all persons.

Caution: The RU may be destroyed if the maximum recommended output signal level at the RU

antenna port is exceeded. Make sure that sufficient attenuation is inserted in the forward path to

prevent the RU from being overdriven.