Spectrum Analyzer Basics Copyright 2000 Agenda ● Overview: ● Whatis spectrum analysis? ● What measurements do we make? ● Theory of Operation: ● Spectrum analyzer hardware ● Specifications: ● Which areimportant and why? ● Features ● Making the analyzer more effective ● Summary ● Appendix
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Spectrum Analyzer Basics Copyright 2000
Agenda
● Overview:● What is spectrum analysis? ● What measurements do we make?
● Theory of Operation:● Spectrum analyzer hardware
● Specifications:● Which are important and why?
● Features● Making the analyzer more effective
● Summary● Appendix
Spectrum Analyzer Basics Copyright 2000
Agenda
● Overview● Theory of Operation● Specifications● Features● Summary● Appendix
Spectrum Analyzer Basics Copyright 2000
OverviewWhat is Spectrum Analysis?
8563ASPECTRU M ANALYZER 9 kHz - 26.5 GHz
Spectrum Analyzer Basics Copyright 2000
OverviewTypes of Tests Made .
ModulationModulation
DistortionDistortion
NoiseNoise
Spectrum Analyzer Basics Copyright 2000
OverviewFrequency versus Time Domain
time
Amplitude(power) freq
uency
Time domainMeasurements
Frequency DomainMeasurements
Spectrum Analyzer Basics Copyright 2000
OverviewDifferent Types of Analyzers
Parallel filters measured simultaneously
LCD shows full spectral display
A
ff1 f2
Fourier Analyzer
Spectrum Analyzer Basics Copyright 2000
OverviewDifferent Types of Analyzers
A
ff1 f2
Filter 'sweeps' over range of interest
LCD shows full spectral display
Swept Analyzer
Spectrum Analyzer Basics Copyright 2000
Agenda
● Overview● Theory of Operation● Specifications● Features● Summary● Appendix
Spectrum Analyzer Basics Copyright 2000
Theory of OperationSpectrum Analyzer Block Diagram
Pre-SelectorOr Low Pass
Filter
CrystalReference
LogAmp
RF inputattenuator
mixerIF filter
detector
videofilter
localoscillator
sweepgenerator
IF gain
Inputsignal
CRT display
Spectrum Analyzer Basics Copyright 2000
Theory of OperationMixer
MIXER
fsig
LOf
fsig LOf
LOf fsig-
LOf fsig+RF
LOIF
input
Spectrum Analyzer Basics Copyright 2000
IF FILTER
Display
InputSpectrum
IF Bandwidth(RB W)
Theory of OperationIF Filter
Spectrum Analyzer Basics Copyright 2000
Theory of OperationDetector DETECTOR
Negative detection: smallest valuein bin displayed
Positive detection: largest valuein bin displayed
Sample detection: last value in bin displayed
"bins"
amplitude
Spectrum Analyzer Basics Copyright 2000
Theory of OperationVideo Filter
VIDEO FILTER
Spectrum Analyzer Basics Copyright 2000
Theory of OperationOther Components
LCD DISPLAY
S WEEP GEN
LO
IF GAIN
frequency
RF INPUT ATTENUATOR
Spectrum Analyzer Basics Copyright 2000
Theory of OperationHow it all works together
3.6(GHz)
(GHz)
0 3 61 2 4 5
0 31 2
3 64 5
3.6
(GHz)0 31 2
fIF
Signal Range LO Range
fs
sweep generator
LO
LCD display
input
mixer
IF filter
detector
A
f
fLO
fs
fs
fs
fLO-
fs
fLO+
fLO
3.6 6.5
6.5
Spectrum Analyzer Basics Copyright 2000
Theory of OperationFront Panel Operation
8563ASPECTRU M ANALYZER 9 kHz - 26.5 GHz
RF Input Numerickeypad
Control functions(RBW, sweep time, VBW)
Primary functions(Frequency, Amplitude,
Span)Softkeys
Spectrum Analyzer Basics Copyright 2000
Agenda
● Overview● Theory of Operation● Specifications● Features● Summary● Appendix
Spectrum Analyzer Basics Copyright 2000
Specifications
8563ASPECTRU M ANALYZER 9 kHz - 26.5 GHz
➤ Frequency Range➤ Accuracy: Frequency & Amplitude➤ Resolution➤ Sensitivity➤ Distortion➤ Dynamic Range
Spectrum Analyzer Basics Copyright 2000
SpecificationsFrequency Range
Measuring harmonics50 GHz and beyond!Measuring harmonics50 GHz and beyond!
Low frequenciesfor baseband and IFLow frequencies
for baseband and IF
Spectrum Analyzer Basics Copyright 2000
SpecificationsAccuracy
AbsoluteAmplitude
in dBm
RelativeAmplitudein dB
RelativeFrequency
Frequency
Spectrum Analyzer Basics Copyright 2000
SpecificationsAccuracy: Frequency Readout Accuracy
Typical datasheet specification:
Spans < 2 MHz: (freq. readout xfreq. ref. accuracy+ 1% of frequency span+ 15% of resolution bandwidth+ 10 Hz "residual error")
+_
Frequency
Spectrum Analyzer Basics Copyright 2000
SpecificationsAccuracy: Frequency Readout Accuracy Example
Single Marker Example:
1% of 400 kHz span15% of 3 kHz RBW10 Hz residual error
+_
2 GHz400 kHz span3 kHz RBW
Calculation: (2x10 Hz) x (1.3x10 /yr.ref.error) 9 -7 ====
AM signal -look at in zero-span, turn on FFT with stop frequency = 4 kHz
ESG-D4000A Sigl Gen
Spec An
8447F Amplifier
Power Splitter(used as combiner)
inout
ESG-D4000A Sigl Gen
On
Off
f=170 MHz, A=-25 dBm
20%AM, 1kHz
Spectrum Analyzer Setup
fc=170 MhzRB W=3 MHzVB W=1 MHzspan= zero
Filter
Signal Generator Setup
Spectrum Analyzer Basics Copyright 2000
FeaturesModulation Measurements: FFT
SPAN 50 kHzCENTER 100 MHz
Spectrum Analyzer Basics Copyright 2000
FeaturesModulation Measurements: AM/FM Detector with Speakers
8563ASPECTRU M ANALYZER 9 kHz - 26.5 GHz
Spectrum Analyzer Basics Copyright 2000
FeaturesModulation Measurements: Time-Gating
1 2 3
45
01
3
4 5 60
12
Time
Frequency
A mplitude
Timeslot
Channel Number
Time Division Multiple Access (TDMA)
user #1
Spectrum Analyzer Basics Copyright 2000
FeaturesModulation Measurements: Time-Gating
EnvelopeDetector
VideoFilter
GATE
Time-Gated Measurements in the Frequency Domain
Frequency
time
"time gating"
Spectrum Analyzer Basics Copyright 2000
FeaturesNoise Measurements: Noise Marker & Video Averaging
8563ASPECTRU M ANALYZER 9 kHz - 26.5 GHz
1.025 MHzMKR -135.75 dBm/Hz
AVG10
Spectrum Analyzer Basics Copyright 2000
FeaturesStimulus Response: Tracking Generator
DUT
SourceReceiver
IF
LO
CRTDisplay
Tracking Generator
Tracking
RF in
Spectrum Analyzer
TG out
Adjust
DUT
Spectrum Analyzer Basics Copyright 2000
Agenda
● Overview● Theory of Operation● Specifications● Features● Summary● Appendix
Spectrum Analyzer Basics Copyright 2000
Agilent Spectrum Analyzer Product Families
856XEC family● 30 Hz up to 50 GHz● high performance● color display● W-CDMA test set● fast, digital 1 Hz RBW
ESA-E Series● 30 Hz to 26.5 GHz● MID-Performance● Flexible Platform● Application Focused Solutions● Color Display● Fast and Accurate
ESA-L series● 9 kHz up to 26 GHz● low cost● general purpose● fully synthesized● rugged
89400 family● DC to 2.65 GHz● vector signal analyzers● digital modulation● complex, time-varying signals● spectrum and time waveform analysis
Spectrum Analyzer Basics Copyright 2000
Agenda
● Overview● Theory of Operation● Specifications● Features● Summary● Appendix
Spectrum Analyzer Basics Copyright 2000
SpecificationsAccuracy: Other Sources of Uncertainty
● Mismatch ● Compression due to overload ● Distortion products● A mplitudes below the log amplifier range● Signals near noise● Noise causing amplitude variations● Two signals incompletely resolved