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, indicating that all of the power is being transmitted correctly.
Carrier Feedthrough
Carrier Feedthrough is a result of the RF carrier signal feeding through the I/Q modulator and riding on the output circuitry without being modulated. Carrier Feedthrough is a common cause of bad Rho measurements.
Noise Floor
Noise Floor is the average power of all the inactive channels.
Pilot Power
Pilot Power is the total power in the Pilot code channel, expressed in dBm. The transmit power of the Pilot Channel signal for a given base station is normally constant.
Delta Page Power
Delta Page Power is the amplitude difference between the Paging Channel and Pilot Channel, expressed in dB. The transmit power of the Paging Channel is constant and can be set at a value relative to the Pilot Power. A common value is -4 dB relative to the Pilot.
Delta Sync Power
Delta Sync Power is the amplitude difference between the Sync Channel and Pilot Channel, expressed in dB. The transmit power of the Sync Channel is constant and may be set at a value relative to the Pilot Power. A common value is -10 dB relative to the Pilot.
Delta Quick Page Channel Power
Delta Quick Page Channel (QPCH) Power is the amplitude difference between the Quick Page Channel and Pilot Channel, expressed in dB. The QPCH is a bursted channel and is not on all the time. In order to capture the level of the QPCH, the statistic measures and holds the peak level of the QPCH. Until a QPCH has been measured, the value will be dashes. When "on", the level of the QPCH is constant and is set at a value relative to the Pilot Power. The QPCH digital gain level can be set to 2, 1, 0, -1, -2, -3, -4, and -5 dB relative to the Pilot.