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Double-Sided Spur
Document Part No. E5500-90024Ed. 1.0
4
Adjust the phase difference at the phase detector to 90 degrees
(quadrature) either by adjusting the synthesizer or by adjusting
an optional variable phase shifter or line stretcher. Quadrature is
achieved when the meter on the front panel of the phase noise
interface is set to zero.
This calibration option has the following requirements:
G
One of the input frequency sources must be capable of being
phase modulated.
G
The resultant sideband spurs from the phase modulation must
have amplitudes that are –100 dB and –20 dB relative to the
carrier amplitude.
G
The offset frequency or modulation frequency must be between
10 Hz and maximum (See the
Advantages:
G
Requires only one RF source
G
Calibration is done under actual measurement conditions so all
non-linearities and harmonics of the phase detector are
calibrated out.
NOTE: Because the calibration is performed under actual
measurement conditions, the Double-sided Spur Method and the
Single-sided Spur Method are the two most accurate calibration
methods.
Disadvantages:
G
Requires a phase modulator which operates at the desired carrier
frequency.
G
Requires audio calibration source.
G
Requires RF spectrum analyzer for manual measurement of
sidebands or preferably a modulation analyzer.
NOTE: Most phase modulators are typically narrow-band devices;
therefore, a wide range of test frequencies may require multiple
phase modulators.
E5500 Phase Noise Measurement System Version A.02.00
Residual Measurement Fundamentals
Calibration Options
"Measured Beatnote"
on page 8-15).
8
ΦM
8-19
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