Agilent Technologies 8935 series e6380a Manuale Utente

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Chapter 5
133
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 
• I/Q magnitude and phase errors (see 
 
and 
)