User's Manual

ADCP-75-132 • Issue 2C • August 2006

Page 45

5.3 RF Input and Output Signal Level Adjustments

The DHU may be connected to either a donor antenna or a base transceiver station through an

ancillary interface device. The following sections provide general guidelines for using the

interface device to adjust the forward and reverse path signals to the correct level.

5.3.1 Forward Path RF Signal Level Adjustment

Use the following procedure to adjust the level of the forward path composite RF signal input

to the DHU so that the maximum RF output signal level is provided at the DRU:

1. Complete all remaining forward path coaxial cable connections between the BTS and the

local interface device or between the antenna and the remote interface device as

specified in the instructions provided with the equipment.

2. Connect a spectrum analyzer or power meter to the forward path output port on the

interface device.

Note: Check the input rating of the test equipment and the output rating of the interface

device. To avoid burning out the spectrum analyzer or power meter, it may be necessary

to insert a 30 dB 100W (or similar) attenuator between the interface device and test

equipment.

3. Adjust the interface device to provide the maximum RF signal level at the output port.

4. If using a spectrum analyzer, proceed to step 5. If using a power meter, measure the

composite signal power from the interface device and then proceed to step 7.

5. Measure the RF level of a single carrier, such as the control channel, in dBm. Make sure

the resolution bandwidth of the spectrum analyzer is 30 kHz.

6. Calculate the total composite signal power from the interface device using the following

formula:

tot

= P

+ 10Log N – (see Note)

Where,

tot

is the total composite power in dBm

is the power per carrier in dBm as measured in step 4

N is the total number of channels.

Note: If calculating the composite power for a CDMA system, reduce the initial result

by 16.23 dBm.

7. Adjust the interface device to provide a composite RF signal level of approximately –20

dBm at the interface device RF output port.

8. Disconnect the test equipment from the interface device

9. Connect the forward path cable (attached to the RF IN connector on the DHU) to the

interface device RF output port.