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Evaluating Your Measurement Results
14
Agilent E5505A User’s Guide
337
.
To list the marked spurs
A list of spurs can be displayed by accessing the
Spurs List
function in the
View
menu.
Forest of spurs
A so called forest of spurs is a group of closely spaced spurs on the phase noise
plot. A forest of spurs is often caused by improper shielding that allows stray
RF energy to be picked up by the DUT wiring, etc. A breadboarded or
prototype circuit should be well shielded from external RF fields when phase
noise measurements are being made.
shows actions to take to eliminate spurs.
Table 53
Spurs on the graph
Offset Frequency
Number of Averages
Upward Change for Marking Spurs (dB)
<
100 kHz
<
4
30
≥
4
17
≥
8
12
≥
30
6
>
100 kHz
Any
4
Table 54
Actions to eliminate spurs
Spur Sources
Description
Recommended Action
Internal
Potential spur sources within the
measurement system include the phase noise
system, the DUT, and the reference source.
Typical system spurs are –120 dBc, and they
occur at the power line and system vibration
frequencies in the range of from 25 Hz to 1
kHz, and above 10 MHz.
If you do not have a plot of the system’s noise and spur
characteristics, perform the system Noise Floor Test. If
you suspect that the DUT or the reference source may
be the spur source, check each source using a spectrum
analyzer or measuring receiver (such as an Agilent
8902A). Also, if additional sources are available, try
exchanging each of the sources and repeating the
measurement.
External
Spur sources external to the system may be
either mechanical or electrical. When using
the Phase Lock Loop measurement technique,
the system’s susceptibility to external spur
sources increases with increases in the Peak
Tuning Range set by the VCO source.
Shorten coaxial cables as much as possible (particularly
the Tune Voltage Output cable). Make sure all cable
connections are tight. It may be possible to identify an
external spur source using a spectrum analyzer with a
pick-up coil or an antenna connected to it.
Содержание E1420B
Страница 24: ...24 Agilent E5505A User s Guide ...
Страница 46: ...46 Agilent E5505A User s Guide 2 Introduction and Measurement ...
Страница 128: ...128 Agilent E5505A User s Guide 5 Absolute Measurement Fundamentals ...
Страница 226: ...226 Agilent E5505A User s Guide 7 Residual Measurement Fundamentals ...
Страница 322: ...322 Agilent E5505A User s Guide 13 Baseband Noise Measurement Examples ...
Страница 340: ...340 Agilent E5505A User s Guide 14 Evaluating Your Measurement Results ...
Страница 358: ...358 Agilent E5505A User s Guide 15 Advanced Software Features ...
Страница 386: ...386 Agilent E5505A User s Guide 16 Reference Graphs and Tables ...
Страница 392: ...392 Agilent E5505A User s Guide 17 System Specifications ...
Страница 404: ...404 Agilent E5505A User s Guide 18 System Interconnections ...
Страница 452: ...452 Agilent E5505A User s Guide 20 PC Digitizer Performance Verification ...
Страница 466: ...466 Agilent E5505A User s Guide 21 Preventive Maintenance ...