DIGIMINI EMEA/APAC/AUSTRALIA REPEATERS
PRODUCT DESCRIPTION AND USER’S MANUAL
www.cobham.com/wireless
Page |
3-6
Date: 11-Oct-15
Rev. 5.0
Cobham Wireless –
Coverage
Document number: 00030UMCD
3.5.1 Verifying Donor and Service Antennas Isolation
CAUTION!!
The isolation between the Base/Donor and Mobile/Service antennas is critical.
Lower isolation can lead to high in-band ripple, oscillations and low signal quality.
The isolation between the Base/Donor and Mobile/Service antennas is critical.
•
For proper operation of the Repeater, it is recommended that the isolation between the Donor
and Service antennas be at least 10dB higher than the Repeaters set gain.
•
Insure proper vertical or horizontal distance separation between Donor and Service antennas
NOTE: Lower isolation can lead to high in-band ripple, oscillations and low signal quality.
To measure the isolation, proceed as follows:
1. Inject a known signal from a signal generator into one antenna (preferably the Donor antenna).
2. Measure the coupled output from the Service antenna, using the Spectrum analyzer and LNA if
applicable.
3. Perform this procedure across the frequency range of both the Uplink and Downlink bands.
4. Register the lower result for system operation.
3.5.2 Verifying Link between the BTS and the Repeater
Before connecting the antennas or powering up the Repeater, verifying the Link between the BTS
and the Repeater
This test checks the signal strength from the BTS antenna to the Repeater.
WARNING!!
Perform this procedure before connecting the antennas to the Repeater or
powering on the Repeater. The Repeater should not be operated prior to the verification of the
operating parameter in its installation environment.
Proceed as follows:
1. Using a Spectrum analyzer, measure the received signal from BTS at the Donor antenna port
near the Repeater.
2. Adjust the Donor antenna direction to receive the maximum signal strength.
3. Compare the received signal strength with the calculated signal strength from the design phase.
In case of discrepancy, check for one of the following:
•
Antenna out of direction
•
Antenna tuned to side lobe instead of main lobe
•
Antenna connector or antenna cable faulty
•
Line-of-sight problem (obstruction), etc.
4. Register the signal strength of the downlink channel for the system operation phase.
