User's Manual

ADCP-75-348 • Issue 1 • 04/2008

Page 16

6.7 Coaxial Cable Connections

The RF interface between the HU DART card and the EBTS/BTS is supported through two type

QMA female connectors mounted on each DART front panel. One connector provides the

coaxial cable connection for the forward path (downlink) signal and the other connector

provides the coaxial cable connection for the reverse path (uplink) signal.

In most installations, it is usually necessary to insert an

external attenuator

into the forward path

link between the HU and the BTS. A signal level that is greater than –9 dBm will overdrive and

possibly damage the HU receiver. Before completing the forward path connection at the BTS,

verify that the composite forward path RF signal level at the HU is between

–25 and +5 dBm

The HU should be mounted as close as possible to the EBTS/BTS to minimize cable losses. Use

the following procedure to route and connect the forward and reverse path coaxial cables to the

HU DART cards:

1. Obtain the required lengths of high performance, flexible, low loss 50-ohm coaxial

communications cable (RG-400 or equivalent) for all coaxial connections.

2. Route the forward and reverse path coaxial cables between the HU and the BTS interface

(per system design plan) and cut to the required length. Allow sufficient slack for dressing

and organizing cables at the HU and for installing an external attenuator in the forward

path link.

3. Terminate each cable with an QMA-Type male connector following the connector

supplier’s recommendations.

4. If required, install an external attenuator in the forward path.

5. Connect the forward path cable to the FWD RF IN connector on the HU DART front

panel as shown in

Figure 12.

6. Connect the reverse path cable to the REV RF OUT connector on the HU DART front

panel (see

Figure 12).

7. Repeat this procedure for the remaining DART cards in the HU.

8. Dress and secure cables at the right side of the HU.

9. Complete all remaining coaxial connections as specified in the system design plan.

Note: The composite forward path RF signal level at the HU must be between –25 and

+5 dBm. Do not connect the forward path cable until the composite forward path RF

signal level is measured and the amount of external attenuation required is determined.