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Chapter 3, Mobile Station CDMA Tests
Rho (Transmitter Waveform Quality)
Measurement Overview
56
The value you obtained during the Rho measurement is based on a comparison, or
cross-correlation, of the actual transmitted signal to the ideal signal transmitting
the same data. Rho represents the percentage of power in the transmitted signal
that correlates with the ideal signal.
Rho measurements give you a very comprehensive indication of transmitter
performance. If there are significant problems with the mobile station's output
power amplifier, I/Q modulator, or filters there is a good chance they will cause
degradation in the Rho measurement value.
When a Rho measurement is made, the following measurements are also made:
•
Frequency Error (see
•
Phase Error (excessive values may be due to filter ripple, I/Q modulator quadrature
errors, or distortion or compression in output power amplifier).
•
Amplitude Error (excessive values may indicate distortion or compression in output
power amplifier).
•
Time Offset (see
table
Carrier Feedthrough (values higher than −25 dB indicate excessive I/Q modulator DC
•
offsets)
•
Average Power and Channel Power
lists some typical test standards:
Table 1
table
1).
1).
Table 1
Rho
Frequency Error
Time Offset
Waveform Quality
>0.944 (94.4%)
±300 Hz
±1 us
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