Technical data

110 Chapter 3
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
that timing must be within 3 µs. If the Time Offset is large enough, an “island cell”
can occur. The “island cell” effect was mentioned already when discussing
Frequency Error.
An access terminal moving outward toward the limit of its cell will need to acquire
the adjacent cell in order to hand off. If the time offset of the target cell is too far
from that of the current site, the handoff may not happen.
The dependence of the access terminal on correct system time limits the physical
distance to a target cell's antenna. Each PN Offset is 52.08 µs; if the propagation
delay is too long, the received PN Offset may be different from the value designated
on the Sync channel. This difference can confuse the access terminal, causing the
handoff to fail.
Another cause of timing error is a bad GPS receiver or timing distribution network
within the access network. To test your access network's GPS and timing
distribution system, you can use the internal GPS receiver to generate an accurate
timing reference for the test set to use while performing access network tests.
Non Idle Power
When making channel power measurements, make sure you have accounted for the
loss of the test cable and high power attenuator you are using. If you do not know
the loss of your test cable and high power attenuator configuration, perform an
insertion loss measurement and enter the insertion loss as the RF In Loss value. For
more information see “Two Port Insertion Loss” on page 123.
If the channel power is lower than expected, verify you have a good connection to
the RF output of the access network. Also, verify the cable you are using to connect
to the access network is not faulty. A low channel power may also indicate a bad
power amplifier.
Inaccurate channel power (high or low) may indicate an incorrect power setting at
the access network.
Pilot + MAC Power
The Pilot + MAC Power is a measurement of the average power during the Pilot and
MAC periods. This is when the transmitter is only sending overhead messages in a
burst mode and is not transmitting any data to users. When the Idle slot activity goes
to zero (no idle slots), the Pilot + MAC and a couple of the other measurements
blank (as they have no meaning when all slots are active).
On/Off Ratio
The On/Off Ratio is a ratio of the Pilot + MAC Power to the Idle Data Power. The