Technical data

578 Chapter 20
W-CDMA or W-CDMA (with HSDPA) Over Air
Using the W-CDMA or W-CDMA (with HSDPA) Over the Air Tool
W-CDMA or W-CDMA (with HSDPA)
Over Air
The E7495A/B test set includes up to six lower energy active pilots in the pilot
dominance calculation.
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 from 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 can appear as noise
interference at the receiver.
The table below gives guidelines to the quality of the over the air code domain
measurements with respect to pilot dominance and multipath power.
The default measurement limits for pilot dominance and multipath power are set to
give “fair” measurement quality. If these limits are met, the pilot dominance and
multipath power values will be displayed in green. When the pilot dominance and
multipath power parameters are outside the acceptable limits, the parameters will
turn red. If this occurs, you must move to a different location that meets the “fair”
criteria defined above.
In general, you should always use a preselector filter for the band of interest to
prevent strong signals from overwhelming the signal of interest. Agilent offers the
following preselector and antenna:
• Option 813—W-CDMA preselector filter and antenna for W-CDMA.
Measurement Quality Pilot Dominance Multipath Power
Very good >= 10 dB < 0.1 dB
Fair > 8dB < 0.4dB
Marginal > 5dB < 0.7dB