Technical data

212 Chapter 7
CDMA Analyzer
Metrics Provided by the CDMA Tx Analyzer Measurement
CDMA Analyzer
Metrics Provided by the CDMA Tx Analyzer
Measurement
This section contains descriptions of the individual CDMA transmit parameters in
the metric display of the screen. The “Interpretation of CDMA Tx Analyzer
Measurement Results” section contains expected result values and possible causes
of error if the expected results are not met.
Frequency Error
Frequency error is the frequency difference between your transmitter's actual center
frequency and the frequency (or channel) you entered.
PN Offset
The PN Offset is a “short code” sequence that provides a unique identifier for each
sector of each cell site. The PN Offsets are applied to the I and Q signals before
modulation. PN Offsets are offset in time by 52.08 µs and they repeat every 26.666
ms. This yields 512 unique short code sequences (0-511). The mobile phone needs
the PN Offset to decode information in the Sync and Paging channels, which are
transmitted by the base station.
Time Offset
The Time Offset compares the PN Offset timing with the overall system time. This
measurement checks the start of the PN offset in comparison to either the GPS
signal or the Even Second clock signal. For example, PN Offset 0 should repeat
exactly on the rising edge of the Even Second clock. PN Offset 1 should repeat
52.08 µs after the rising edge of the Even Second clock, and so forth. Any error in
time from that event is reported as a Time Offset.
Channel Power
Channel Power is the integrated power within a defined bandwidth. For CDMA the
channel bandwidth is defined to be 1.25 MHz. Channel Power measures the power
the base station is transmitting across the entire 1.25 MHz CDMA channel.
Estimated Rho
Estimated Rho is the measure of the modulation quality for a CDMA transmitter.
This measurement is analogous to measuring FM accuracy and distortion in an
AMPS network or EVM in a TDMA system. A Rho value of 1.0 is perfect,