Technical data

Chapter 3 111
1xEV-DO Analyzer and Over Air Test
Interpretation of 1xEV-DO Tx and Over Air Analyzer Measurement
Results
1xEV-DO Analyzer and Over Air
Test
recommended minimum On/Off Ratio for idle slots was set to 7dB in the standard to
allow Access Network manufacturers to protect the power amplifiers from large
output power swings between On portions of the signal during bursts and Off
portions of the signal in idle slots. Each manufacture may set this value to different
levels. This parameter is loaded into the radios from the Switch.
When the Idle slot activity goes to zero (no idle slots), the On/Off Ratio and a couple
of the other measurements blank (as they have no meaning when all slots are active).
Idle Data Pwr
This is the average power level in the data portion, averaged across all idle slots in
the acquired capture, and can contribute to the overall Noise Floor in the system. A
high reading here combined with a high reading in the CDP Noise Floor can indicate
a problem with the I/Q Modulator or indicates the amplifier is being overdriven.
When the Idle slot activity goes to zero (no idle slots), the Idle Data Power and a
couple of the other measurements blank (as they have no meaning when all slots are
active).
Idle Slots
This reading is a measure of the number of idle slots, measured as a percentage of
the total number of slots available. This reading can be used as a flag to add more
capacity at the site as the reading approaches 0%.
Est Pilot Rho
The 1xEV-DO access network standard specifies that Rho must be greater than
0.912. Typical values for a healthy access network are greater than 0.94.
Rho failures can indicate problems in:
• Compression in linear amplifiers
• Magnitude and phase errors in the IQ modulator
• Phase non-linearity (group delay)
• Spurious signals in the transmission path
• Carrier feedthrough
Because the uncorrelated power appears as interference to the access terminals, poor
Rho performance will affect the sector's capacity. The added interference can
require that the signal on traffic channels be raised to overcome the interference.
This may, in turn, be seen as further interference. At some point, the site will have to
shed calls in order to supply the remaining calls with enough signal versus the
interference in the system.