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1Spectrum Analysis BasicsCMB 12/96
8563A SPECTRUM ANALYZER 9 kHz - 26.5 GHz
2Spectrum Analysis BasicsCMB 12/96
Spectrum Analysis BasicsCMB 12/96
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 moreeffective
Summary
3Spectrum Analysis BasicsCMB 12/96
Agenda
Overview Theory of Operation Specifications Features Summary
4Spectrum Analysis BasicsCMB 12/96
OverviewWhat is Spectrum Analysis?
8563A SPECTRUM ANALYZER 9 kHz - 26.5 GHz
5Spectrum Analysis BasicsCMB 12/96
OverviewTypes of Tests Made
Modulation
Distortion
Noise
6Spectrum Analysis BasicsCMB 12/96
OverviewFrequency versus Time Domain
time
Amplitude(power) frequency
Time domainMeasurements Frequency Domain
Measurements
7Spectrum Analysis BasicsCMB 12/96
OverviewDifferent Types of Analyzers
Parallel filters measuredsimultaneously
CRT shows fullspectral display
A
ff1 f2
Fourier Analyzer
8Spectrum Analysis BasicsCMB 12/96
OverviewDifferent Types of Analyzers
A
ff1 f2
Filter 'sweeps' over rangeof interest
CRT shows fullspectral display
Swept Analyzer
9Spectrum Analysis BasicsCMB 12/96
Agenda
Overview Theory of Operation Specifications Features Summary
10Spectrum Analysis BasicsCMB 12/96
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
11Spectrum Analysis BasicsCMB 12/96
Theory of OperationMixer MIXER
f sig
LOf
fsig LOf
LOf fsig-LOf fsig+RF
LOIF
input
12Spectrum Analysis BasicsCMB 12/96
Theory of OperationIF Filter IF FILTER
Display
InputSpectrum
IF Bandwidth(RBW)
13Spectrum Analysis BasicsCMB 12/96
Theory of OperationDetector DETECTOR
Negative detection: smallest value in bin displayed
Positive detection: largest value in bin displayed
Sample detection: last value in bindisplayed
"bins"
amplitude
14Spectrum Analysis BasicsCMB 12/96
Theory of OperationVideo Filter
VIDEOFILTER
15Spectrum Analysis BasicsCMB 12/96
Theory of OperationOther Components
CRT DISPLAY
SWEEPGEN
LO
IF GAIN
frequency
RF INPUTATTENUATOR
16Spectrum Analysis BasicsCMB 12/96
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
f IF
Signal Range LO Range
f s
sweep generator
LO
CRT display
input
mixer
IF filter
detector
A
f
f LO
f s
f s
f sf LO
- f sf LO
+f LO
3.6 6.5
6.5
17Spectrum Analysis BasicsCMB 12/96
Theory of OperationFront Panel Operation
8563ASPECTRUM ANALYZER 9 kHz - 26.5 GHz
RF Input Numerickeypad
Control functions(RBW, sweeptime, VBW)
Primary functions(Frequency, Amplitude,
Span)Softkeys
18Spectrum Analysis BasicsCMB 12/96
Agenda
Overview Theory of Operation Specifications Features Summary
19Spectrum Analysis BasicsCMB 12/96
Specifications
8563A SPECTRUM ANALYZER 9 kHz - 26.5 GHz
Frequency RangeAccuracy, Frequency & AmplitudeResolutionSensitivityDistortionDynamic Range
20Spectrum Analysis BasicsCMB 12/96
SpecificationsFrequency Range
Measuring harmonics50 GHz and beyond!
Low frequenciesfor baseband and IF
21Spectrum Analysis BasicsCMB 12/96
SpecificationsAccuracy
AbsoluteAmplitude
in dBm
RelativeAmplitudein dB
RelativeFrequency
Frequency
22Spectrum Analysis BasicsCMB 12/96
SpecificationsAccuracy: Frequency Readout Accuracy
Typical datasheet specification:
Spans < 2 MHz: ± (freq. readout x freq. ref. Accuracy + 1% of frequency span + 15% of resolution bandwidth + 10 Hz "residual error")
23Spectrum Analysis BasicsCMB 12/96
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 ====
260 Hz4000 Hz450 Hz
10 Hz4720 HzTotal =
24Spectrum Analysis BasicsCMB 12/96
SpecificationsAccuracy: Relative Amplitude Accuracy
Display fidelity Frequency response RF Input attenuator Reference level Resolution bandwidth CRT scaling
25Spectrum Analysis BasicsCMB 12/96
SpecificationsAccuracy: Relative Amplitude Accuracy - DisplayFidelity
Applies when signals are not placed at thesame reference amplitude
Display fidelity includes–Log amplifier or linear fidelity–Detector linearity–Digitizing circuit linearity
Technique for best accuracy
26Spectrum Analysis BasicsCMB 12/96
SpecificationsAccuracy: Relative Amplitude Accuracy - Freq.Response
- 1 dB
+1 dB
0
BAND 1
Specification: ± 1 dB
Signals in the Same Harmonic Band
27Spectrum Analysis BasicsCMB 12/96
SpecificationsAccuracy: Relative Amplitude Accuracy
RF Input attenuator Reference level Resolution bandwidth CRT scaling
28Spectrum Analysis BasicsCMB 12/96
SpecificationsAccuracy: Absolute Amplitude Accuracy
Calibrator accuracy
Frequency response
Reference level uncertainty
29Spectrum Analysis BasicsCMB 12/96
SpecificationsAccuracy: Other Sources of Uncertainty
Mismatch Compression due to overload Distortion products Amplitudes below the log amplifier range Signals near noise Noise causing amplitude variations Two signals incompletely resolved
(RF input port not exactly 50 ohms)(high-levelinput signal)
30Spectrum Analysis BasicsCMB 12/96
SpecificationsResolution
ResolutionBandwidth
Residual FM
Noise Sidebands
What Determines Resolution?
RBW Type andSelectivity
31Spectrum Analysis BasicsCMB 12/96
SpecificationsResolution: Resolution Bandwidth
.
3 dB3 dB BW
LO
Mixer
IF Filter/Resolution Bandwidth Filter
(RBW)Sweep
Detector
InputSpectrum
Display
RBW
32Spectrum Analysis BasicsCMB 12/96
SpecificationsResolution: Resolution Bandwidth
3 dB
10 kHz
10 kHz RBW
33Spectrum Analysis BasicsCMB 12/96
SpecificationsResolution: RBW Type and Selectivity
3 dB
60 dB
60 dBBW
60 dB BW3 dB BW
3 dB BW
Selectivity =
34Spectrum Analysis BasicsCMB 12/96
SpecificationsResolution: RBW Type and Selectivity
10 kHz
RBW = 10 kHzRBW = 1 kHzSelectivity 15:1
10 kHz
distortionproducts
60 dB BW= 15 kHz
7.5 kHz
3 dB
60 dB
35Spectrum Analysis BasicsCMB 12/96
SpecificationsResolution: Residual FM
Residual FM"Smears" the Signal
36Spectrum Analysis BasicsCMB 12/96
SpecificationsResolution: Noise Sidebands
Noise Sidebands can preventresolution of unequal signals
Phase Noise
37Spectrum Analysis BasicsCMB 12/96
SpecificationsResolution: RBW Determines Measurement Time
Penalty For Sweeping Too FastIs An Uncalibrated Display
Swept too fast
38Spectrum Analysis BasicsCMB 12/96
SpecificationsResolution: Digital Resolution Bandwidths
DIGITAL FILTER
ANALOG FILTER
SPAN 3 kHzRES BW 100 Hz
Typical Selectivity Analog 15:1 Digital 5:1
39Spectrum Analysis BasicsCMB 12/96
SpecificationsSensitivity/DANL
Sweep
LO
MixerRF
InputRES BW
Filter
Detector
A Spectrum Analyzer Generates and Amplifies NoiseJust Like Any Active Circuit
40Spectrum Analysis BasicsCMB 12/96
SpecificationsSensitivity/DANL
10 dB
Attenuation = 10 dB Attenuation = 20 dB
signal level
Effective Level of Displayed Noise is aFunction of RF Input Attenuation
Signal-To-Noise Ratio Decreases asRF Input Attenuation is Increased
41Spectrum Analysis BasicsCMB 12/96
SpecificationsSensitivity/DANL: IF Filter (RBW)
Decreased BW = Decreased Noise
100 kHz RBW
10 kHz RBW
1 kHz RBW
10 dB
10 dB
Displayed Noise is a Function of IFFilter Bandwidth
42Spectrum Analysis BasicsCMB 12/96
SpecificationsSensitivity/DANL: VBW
Video BW Smoothes Noise for EasierIdentification of Low Level Signals
43Spectrum Analysis BasicsCMB 12/96
SpecificationsSensitivity/DANL
SignalEqualsNoise
Sensitivity is the Smallest Signal ThatCan Be Measured
2.2 dB
44Spectrum Analysis BasicsCMB 12/96
SpecificationsSensitivity/DANL
Narrowest Resolution BW
Minimum RF Input Attenuation
Sufficient Video Filtering(Video BW < .01 Res BW)
For Best Sensitivity Use:
45Spectrum Analysis BasicsCMB 12/96
SpecificationsDistortion
Frequency TranslatedSignals
Signal ToBe Measured
Resultant
Mixer GeneratedDistortion
Mixers Generate Distortion
46Spectrum Analysis BasicsCMB 12/96
SpecificationsDistortion
Two-Toned Intermod Harmonic Distortion
Most Influential Distortion is theSecond and Third Order
< -50 dBc < -50 dBc< -40 dBc
47Spectrum Analysis BasicsCMB 12/96
SpecificationsDistortionDistortion Products Increase as aFunction of Fundamental's Power
Second Order: 2 dB/dB of FundamentalThird Order: 3 dB/dB of Fundamental
3
f 2f 3f
Powerin dB
2
f f2f - f1 2 1 2
Powerin dB
33
2 12f - f
Two-Toned Intermod
Harmonic Distortion
Third-order distortion
Second-order distortion
48Spectrum Analysis BasicsCMB 12/96
SpecificationsDistortion
Relative Amplitude Distortion Changes withInput Power Level
f 2f 3f
1 dB
3 dB2 dB
21 dB
20 dB1 dB
49Spectrum Analysis BasicsCMB 12/96
SpecificationsDistortion
Distortion is a Function ofMixer Level
POWER AT MIXER =INPUT - ATTENUATOR SETTING dBm
DIS
TOR
TIO
N, d
Bc
0
-20
-40
-60
-80
-100
-60 -30 0 +30
.
TOI
SecondOrder
ThirdOrder
50Spectrum Analysis BasicsCMB 12/96
SpecificationsDistortion
Distortion Test:Is it Internally or Externally Generated?
IF GAIN
No change in amplitude= distortion is part ofinput signal (external)
Change InputAttn by 10 dB
1 Watch Signal onScreen:
2
Change in amplitude = atleast some of the distortionis being generated insidethe analyzer (internal)
RF INPUTATTENUATOR
51Spectrum Analysis BasicsCMB 12/96
SpecificationsDynamic Range
DynamicRange
52Spectrum Analysis BasicsCMB 12/96
SpecificationsDynamic Range
POWER AT MIXER =INPUT - ATTENUATOR SETTING dBm
SIG
NA
L-TO
-NO
ISE
RA
TIO
, dB
c
0
-20
-40
-60
-80
-100
-60 -30 0 +30
.
Displayed Noise ina 1 kHz RBW
Displayed Noise ina 100 Hz RBW
Signal-to-Noise Ratio Can Be Graphed
53Spectrum Analysis BasicsCMB 12/96
SpecificationsDynamic Range
Dynamic Range Can Be Presented Graphically
POWER AT MIXER =INPUT - ATTENUATOR SETTING dBm
SIG
NA
L-TO
-NO
ISE
RA
TIO
, dB
c
-20
-40
-60
-80
-100
-60 -30 0 +30
..
TOI
Optimum MixerLevels
Maximum 2nd OrderDynamic Range
DISPLAYED NOISE (1 kHz RBW)
THIR
D ORDER
SECOND ORDER
Maximum 3rd OrderDynamic Range
SOI
54Spectrum Analysis BasicsCMB 12/96
SpecificationsDynamic Range
Where TOI = Mixer Level - dBc/2
SOI = Mixer Level - dBc
Optimum Mixer Level = DANL - MDR
Attenuation = Signal - Optimum Mixer Level
MDR = 2/3 (DANL - TOI)3
MDR = 1/2 (DANL - SOI)2
Calculated Maximum Dynamic Range
55Spectrum Analysis BasicsCMB 12/96
SpecificationsDynamic Range
Where TOI = (-30) - (-70)/2 = + 5 dBm
3MDR = 2/3 [(-115) - (+5)]
= -80 dBc (1 kHz RBW)
Example Calculation
Optimum Mixer Level = (-115) - (-80) = -35 dBm
Attenuation = (0) - (-35) = +35 dBm
56Spectrum Analysis BasicsCMB 12/96
SpecificationsDynamic Range
Noise Sidebands
Dynamic RangeLimited By Noise Sidebands
dBc/Hz
Displayed AverageNoise Level
Dynamic Range
Compression/NoiseLimited By
100 kHzto
1 MHz
Dynamic Range for Spur Search Depends onCloseness to Carrier
57Spectrum Analysis BasicsCMB 12/96
SpecificationsDynamic Range
Actual Dynamic Range is the Minimum of:
Noise sidebands at the offset frequency
Maximum dynamic range calculation
Calculated from:distortionsensitivity
58Spectrum Analysis BasicsCMB 12/96
SpecificationsDynamic Range
+30 dBm
-115 dBm (1 kHz BW & 0 dB ATTENUATION)
MAXIMUM POWER LEVEL
CRT-DISPLAY
RANGE80 dB
-10 dBm
-35 dBm
-45 dBm
INCREASINGBANDWIDTH ORATTENUATION
SECOND-ORDER DISTORTION
MIXER COMPRESSION
THIRD-ORDER DISTORTION
SIGNAL/NOISERANGE105 dB
RANGE145 dB
MEASUREMENT
MINIMUM NOISE FLOOR
70 dB RANGEDISTORTION
80 dB RANGEDISTORTION
0 dBc NOISE SIDEBANDS
60 dBc/1kHz
SIGNAL /3rd ORDER
SIGNAL/ 2nd ORDER
SIGNAL/NOISE SIDEBANDS
59Spectrum Analysis BasicsCMB 12/96
60Spectrum Analysis BasicsCMB 12/96
61Spectrum Analysis BasicsCMB 12/96
62Spectrum Analysis BasicsCMB 12/96
Agenda
Overview Theory of Operation Specifications Features Summary
63Spectrum Analysis BasicsCMB 12/96
Features
8563A SPECTRUM ANALYZER 9 kHz - 26.5 GHz
Basic Operation remote operation markers limit lines
Noise Measurementsnoise markeraveraging
Modulation Measurements time domainFFTAM/FM detector time-gating
Stimulus Response Measurementstracking generator
64Spectrum Analysis BasicsCMB 12/96
FeaturesBasic Operation: Remote Operation, Markers & LimitLines
8563A SPECTRUM ANALYZER 9 kHz - 26.5 GHz
MARKER1.025 MHz-54.04 dB
65Spectrum Analysis BasicsCMB 12/96
FeaturesModulation Measurements: Time Domain
LIN
MARKER10 msec1.000 X
CENTER 100 MHz SPAN 0 HzRES BW 1 MHz VBW 3 MHz SWP 50 msec
66Spectrum Analysis BasicsCMB 12/96
FeaturesModulation Measurements: FFT
LIN
CENTER 100 MHz SPAN 0 Hz
MARKER1 kHz-26 dBc
10 dB/
CENTER 100 MHz SPAN 10 kHz
MARKER1 kHz-26 dBc
Swept Frequency Domain FFT Frequency Domain
67Spectrum Analysis BasicsCMB 12/96
FeaturesModulation Measurements: FFT
SPAN 50 kHzCENTER 100 MHz
68Spectrum Analysis BasicsCMB 12/96
FeaturesModulation Measurements: AM/FM Detector with Speakers
8563A SPECTRUM ANALYZER 9 kHz - 26.5 GHz
69Spectrum Analysis BasicsCMB 12/96
FeaturesModulation Measurements: Time-Gating
1 2 3
45
01
3
4 5 60
12
Time
Frequency
Amplitude
Timeslot
Channel Number
Time Division Multiple Access (TDMA)
user #1
70Spectrum Analysis BasicsCMB 12/96
FeaturesModulation Measurements: Time-Gating
EnvelopeDetector
VideoFilter
GATE
Time-Gated Measurements in theFrequency Domain
Frequency
time
"time gating"gatedelay
gatelength
71Spectrum Analysis BasicsCMB 12/96
FeaturesNoise Measurements: Noise Marker & Video Averaging
8563A SPECTRUM ANALYZER 9 kHz - 26.5 GHz
1.025 MHzMKR-135.75 dBm/Hz
AVG10
72Spectrum Analysis BasicsCMB 12/96
FeaturesStimulus Response: Tracking Generator
DUT
SourceReceiver
IF
LO
CRTDisplay
Tracking Generator
Tracking
RF inSpectrum Analyzer
TG out
Adjust
DU
T
73Spectrum Analysis BasicsCMB 12/96
Agenda
Overview Theory of Operation Specifications Features Summary