Keysight Technologies N5511A User Manual page 265

AM Noise Measurement Fundamentals
Calibration and Measurement General Guidelines
— Calibration is done under actual measurement conditions so all
Disadvantages
— Requires a second RF source with very accurate AM modulation and output
This method is identical to method 1, however a reference with modulation
capabilities is used to calibrate the measurement.
1. Connect the device under test in a single channel or dual channel
Figure 11-9 Double-Sided spur AM noise setup (method 2, example 1)
2. Measure the power which will be applied to the AM detector.
3. Replace the DUT with a source with AM. Set the output power equal to the
N5511A Phase Noise Test System User's Guide
non-linearities and harmonics of the AM detector are calibrated out. The
double-sided spur method and the single-sided-spur method are the two
most accurate methods for this reason.
power sufficient to match the DUT. If the AM modulation is not very
accurate, a modulation analyzer must be used to make manual
measurement of the AM sidebands.
configuration. See Figure
power measured. The source should be adjusted such that the sidebands
are between -30 dB and -60 dB below the carrier with a modulation rate
between 10 Hz and 20 MHz.
These values are directly entered into the software. When measurement is
performed, there will not be a 6 dB difference as observed in an absolute
or residual measurement as AM is not being suppressed in this
measurement. See Figure
11-9.
11-10.
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