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50
Agilent E5505A User’s Guide
3
Phase Noise Basics
Where BW (bandwidth is negligible with respect to any changes in
versus
the fourier frequency or offset frequency (f).
L(f)
Another useful measure of noise energy is L(f), which is then directly
related to
by a simple approximation which has generally negligible error
if the modulation sidebands are such that the total phase deviation are much
less than 1 radian (
∆φ
pk
<< radian).
L(f) is an indirect measurement of noise energy easily related to the RF power
spectrum observed on an RF analyzer.
shows that the National
Institute of Standards and Technology (NIST) defines L(f) as the ratio of the
power--at an offset (
f)
Hertz away from the carrier. The phase modulation
sideband is based on a per Hertz of bandwidth spectral density and or offset
frequency in one phase modulation sideband, on a per Hertz of bandwidth
spectral density and
(f)
equals the Fourier frequency or offset frequency.
= single sideband (SSB) phase noise to carrier ration (per Hertz)
Figure 15
CW signal sidebands viewed in the frequency domain
S
φ
f
( )
∆φ
2
rms f
( )
BW used to measure
∆φ
rms
--------------------------------------------------------------------------
rad 2
Hz
------------
=
=
S
φ
S
φ
f
( )
L
f
( )
1
2
---
S
∆φ
f
( )
=
e5505a_user_CW_sidebands_freq.ai
rev2 10/20/03
L
f
( )
p ower d ensity in one ph ase modu lation sideban d
(
)
to tal signa l power
----------------------------------------------------------------------------------------------------------------------------------------
Pssb
Ps
------------
=
=
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 ...