Agilent Technologies 8935 series e6380a manual Rho Measurements

CDMA Measurements - Screens and Control Fields

CDMA Measurements

ADC FS

ADC FS is displayed when channel power is measured. ADC FS indicates how close the measured power level is to the maximum allowed input level at the RF IN/OUT port for a particular Gain setting (on the CDMA ANALYZER screen). Changes to ADC FS can be made by altering the Gain field setting and by altering the signal level into the RF IN/OUT port. ADC FS should be between − 1.0 and − 0.5 dB. Measurement accuracy may be degraded if ADC FS goes below − 10 dB when the Gain field is set to Auto, and can be manually set up to − 0.5 dB when set to Hold. The measurement will be aborted if ADC FS goes above.

Screens on which this measurement is displayed

•CDMA ANALYZER

•CDMA GENERATOR

Rho Measurements

Rho

Rho is a measure of CDMA waveform quality which indicates how well the measured signal (the pilot signal transmitted by the base station under test) correlates with the ideal reference waveform (the ideal pilot generated by the Test Set which is mathematically perfect). This measurement is done through a complex DSP algorithm. Perfect correlation is when rho is equal to 1. The CDMA standard specifies 0.912 as the minimum accepted performance for CDMA base stations.

To make rho measurements, the base station needs to be configured to transmit only a pilot signal. The test equipment is then triggered by any of the selectable CDMA clocks.

Many different factors can contribute to rho failure, including:

•compression in the linear power amplifier

•phase non-linearities (group delay)

•carrier feedthrough (see “Carrier Feedthrough” on page 136)

•I/Q magnitude and phase errors (see “Magnitude Error” on page 138 and “Phase Error” on page 138)

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