Tektronix RSA6100A Series, Help Manual

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RF Measurements > Phase Noise Phase Noise Display
Readout Description
Carrier power The power level at the carrier frequency.
Freq Error
The measured carrier frequency error.
RMS Phase Noise The RMS value of the phase noise, measured over the Integration BW.
Jitter The jitter in seconds, measured over the Integration BW. Includes the effects of random
and coherent jitter.
Residual FM The residual frequency modulation, measured over the Integration BW.
Trace 1
The phase noise on trace 1 at different frequency offset values. Note that if Trace 1 is set
to +/- Peak detection, the value displayed in the table is the +Peak value.
Trace 2 The phase noise on trace 2 at different frequency offset values. Note that if Trace 2 is set
to +/- Peak detection, the value displayed in the table is the +Peak value.
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Changing the Phase Noise Settings (see page 174)
How Phase Noise Is Measured
If carrier tracking is on, the instrument measures phase noise relative to the highest-amplitude signal within
about 20 MHz of the user-entered frequency. The difference between center frequency and the frequency
of the measured carrier is reported as frequency error. If carrier tracking is not on, the instrument measures
phase noise relative to the amplitude at the user-entered frequency.
The unit will tune to a number of offsets from the carrier frequency, and calculate the spectrum for the
frequency range about each offset using a resolution bandwidth appropriate for the offset frequency.
This is done to optimize speed while maintaining acceptable frequency resolution. A table of the values
used for measurement frequency offset, resolution bandwidths, hardware IF
fi lter bandwidths and RF
attenuations is shown below.
Measurement frequency
offset range Measured
span
RBW use
for spectrum
calculation
Hardware IF fi lter RF Attenuation
10 Hz to 100 Hz 312.5 kHz 1 Hz 40 MHz Auto from ref level
100 Hz to 1 kHz 312.5 kHz 2 Hz 40 MHz Auto from ref level
1 kHz to 10 kHz 312.5 kHz 20 Hz 40 MHz Auto from ref level
10 kHz to 100 kHz 3 MHz 200 Hz 40 MHz Auto from ref level
100 kHz to 1 MHz 3 MHz 1 kHz 40 MHz Auto from ref level
1.0 MHz to 1.9 MHz 300 kHz 1 kHz 1 MHz Auto from ref level (-5 dB) 1
1.9 MHz to 20.0 MHz 300 kHz 1 kHz 1 MHz Auto from ref level (-20 dB) 1
20 MHz to 100 MHz 20 MHz 10 kHz 40 MHz Auto from ref level (-5 dB) 1
100 MHz to 1000 MHz 20 MHz 100 kHz 40 MHz Auto from ref level (-5 dB) 1
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1 Attenuator adjustment when ‘optimize dynamic range’ is selected
After acquisition and calculation, the spectrum is corrected to display power in a 1 Hz bandwidth
referenced to the carrier power (dBc/Hz). The correction algorithm does not discriminate between noise
signals and coherent signals in making the dBc/Hz correction. Since all measured signals are corrected as
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RSA6100A Series Real-Time Spectrum Analyzers Help