Technical data

Chapter 3 69
1xEV-DO Analyzer and Over Air Test
Criteria for Making Valid 1xEV-DO Over Air Measurements
1xEV-DO Analyzer and Over Air
Test
Criteria for Making Valid 1xEV-DO Over Air
Measurements
The first step in making valid 1xEV-DO over air measurements is to identify a target
base station to measure. Then, for your measurements to be valid, you must find a
location near the target base station with a sufficiently strong 1xEV-DO signal.
1xEV-DO over air measurements will experience interference from other 1xEV-DO
signals on the same RF channel and from multipath echoes. The code domain power
view measures two key parameters to indicate these effects:
• Pilot dominance—The difference between the useful energy of the strongest
pilot channel and the combined energy of the lower energy active pilot channels
(expressed in dB). Ideally, this value should be very large ( 16 dB).
The E7495A/B test set includes up to nine lower energy active pilots in the pilot
dominance calculation. In live testing of 1xEV-DO networks, however, it is
unlikely that you will have as many as nine interfering pilots.
NOTE It is important to remember that the pilot dominance is always measured against the
strongest signal. If you have specified your channel of interest manually, this
channel might not necessarily be the strongest.
• Multipath power—The amount of power, of the dominant pilot signal, that is
dispersed outside the main correlation peak due to multipath echoes (expressed
in dB). Ideally, this value should be very small (< 0.1 dB). Multipath power is
the result of portions of the original broadcast signal arriving at the receiving
antenna out of phase with the main power of the original signal. This can be
caused by the signal being reflected off objects, such as buildings, or being
refracted through the atmosphere differently from the main signal. These out of
phase signals can cancel power from the main signal or appear as noise
interference at the receiver.
The table below shows the quality of the over air code domain measurements with
respect to pilot dominance and multipath power.
Measurement Quality Pilot Dominance Multipath Power
Very good > 16 dB < 0.1 dB
Fair > 10 dB < 0.4 dB