Technical data

68 Chapter 3
1xEV-DO Analyzer and Over Air Test
Preparing to Make 1xEV-DO Over Air Measurements
1xEV-DO Analyzer and Over Air
Test
Preparing to Make 1xEV-DO Over Air Measurements
An important consideration when making 1xEV-DO over air measurements is your
location relative to the base station. There must be no obstructions between your
location and the base station antennas.
You must select the type of time reference to be GPS. The GPS antenna must be able
to “see” the satellites to obtain lock, and you must have a GPS lock to perform
measurements.
GPS provides an independent time reference that can help determine if the access
network under test is synchronized with the rest of the network. Access networks
not synchronized with the rest of the network are referred to as “island cells”.
NOTE Once your test instrument successfully locks onto the GPS time reference, you will
be able to see all the metrics, and you will be able to verify that the access network
has correctly locked onto the GPS signal.
You need to know, and to enter on the test analyzer, the channel or frequency of the
1xEV-DO signal to be analyzed.
Each access network sector has a unique PN offset. If you know this, you can enter
it manually. If you do not know the PN Offset, you can set PN Offset to Auto, and
let the analyzer find the PN offset of the strongest pilot signal for you. You can also
use the PN Scanner to identify all active PNs in the area. For more information on
PN offsets refer to the “Metrics Provided by the 1xEV-DO Tx and Over Air
Analyzer Measurement” on page 104.
Once you have connected the proper antenna to the test set, chosen a stationary
location, and verified that you have a clear view of the base station antennas, you
can perform 1xEV-DO over air measurements.
If this is the first 1xEV-DO over air measurement for this base station, you must find
a location that meets the criteria for making a valid measurement. Your location
must have a dominant pilot and very low multipath power. If you have made
1xEV-DO over air measurements at this location before and know it provides valid
measurements, skip to “Performing a Basic 1xEV-DO Over Air Measurement” on
page 71.