Agenda. Spectrum AnalyzerBasics

Transcription

1 Agenda Overview : W hatis spectrum analysis? W hatm easurem ents do we make? Theory ofoperation: Spectrum analyzerhardw are Specifications: Which are importantand why? Features Making the analyzermore effective Sum m ary Appendix

2 Overview Types oftests M ade. M odulation M odulation Noise Distortion

3 Overview Frequency versus Time Domain Am plitude (pow er) frequency time Time dom ain M easurem ents Frequency Dom ain M easurem ents

4 Overview DifferentTypes ofanalyzers Fourier Analyzer A Para lelfilters m easured simultaneously LCD show s fu l spectraldisplay f 1 f 2 f

5 Overview DifferentTypes ofanalyzers SweptAnalyzer A Filter'sw eeps'overrange ofinterest LCD show s fu l spectraldisplay f 1 f 2 f

6 Theory ofo peration Spectrum AnalyzerBlock Diagram RF input attenuator mixer IF gain IF filter detector Input signal Pre-Selector OrLow Pass Filter local oscilator Log Am p video filter sw eep generator Crystal Reference CRT display

7 Theory ofo peration Mixer input MIXER f sig RF IF LO f sig f LO -f sig f LO f LO + f sig f LO

8 Theory ofo peration IF Filter IF FILTER Input Spectrum IF Bandw idth (RBW ) Display

9 Theory ofo peration Detector DETECTOR am plitud e "bins" Positive detection:largestvalue in bin displayed Negative detection:sm a lestvalue in bin displayed Sam ple detection:lastvalue in bin displayed

10 Theory ofo peration Video Filter VIDEO FILTER

11 Theory ofo peration O therc om ponents LO RF INPUT ATTENUATOR IF GAIN SW EEP GEN frequency LCD DISPLAY

12 Theory ofo peration How ita lworks together f s SignalRange LO R ange (GHz) f - LO f s f LO f LO +f s f s IF filter input mixer f s detector 3.6 sw eep generator f IF A LO f LO (GHz) LCD display (GHz) f

13 SPEC TR UM ANALYZER 9 kh z GHz Softkeys Theory ofo peration FrontPanelOperation Prim ary functions (Frequency,Am plitude, Span) 8563A C ontrolfunctions (R BW,sw eep time,vbw ) RF Input Numeric keypad

14 SPEC TR UM ANALYZER 9 kh z GHz Specifications 8563A Frequency R ange Accuracy:Frequency & Am plitude Resolution Sensitivity Distortion Dynamic R ange

15 Specifications Frequency R ange Low Low frequencies forbaseband and and IF IF M easuring harm onics GHz and and beyond!

16 Specifications Accuracy Absolute Am plitude in dbm Relative Am plitude in db Frequency Relative Frequency

17 Specifications Accuracy:Frequency R eadoutaccuracy Typicaldatasheetspecification: Spans < 2 MHz: +_ (freq.readoutx freq.ref.accuracy + 1% offrequency span + 15% ofresolution bandw idth + 10 Hz "residualerror") Frequency

18 Specifications Accuracy:Frequency R eadoutaccuracy Exam ple Single M arkerexam ple: 2 GHz 400 kh z span 3 kh z RBW 9-7 Calculation: (2x10 Hz)x (1.3x10 /yr.ref.error) 1% of400 kh z span 15% of3 kh z RBW 10 Hz residualerror Total= = = = = +_ 260 Hz 4000 Hz 450 Hz 10 Hz 4720 Hz

19 Specifications R esolution:resolution Bandw idth Mixer 3 db BW 3 db Detector Input Spectrum LO IF Filter/ Resolution Bandw idth Filter (RBW ) Sweep RBW Display

20 Specifications Resolution:RBW Type and Selectivity 3 db 3 db BW 60 db 60 db BW Selectivity = 60 db BW 3 db BW

21 Specifications Resolution:RBW Type and Selectivity RBW = 1 kh z Selectivity 15:1 RBW = 10 kh z 3 db 7.5 kh z distortion products 60 db 60 db BW = 15 kh z 10 kh z 10 kh z

22 Specifications Resolution:ResidualFM ResidualFM "Sm ears" the Signal

23 Specifications Resolution:Noise Sidebands Phase Noise Noise Sidebands can prevent resolution ofunequalsignals

24 Specifications Resolution:RBW Determines Measurem enttime Swepttoo fast Penalty For Sw eeping Too Fast Is An Uncalibrated Display

25 Specifications Sensitivity/DANL Effective LevelofDisplayed Noise is is a Function ofrf InputAttenuation signallevel 10 db Attenuation = 10 db Attenuation = 20 db Signal-To-Noise Ratio Decreases as RF InputAttenuation is Increased

26 Specifications Sensitivity/DANL Sensitivity is is the Sm a lestsignalthat C an Be Measured Signal Equals Noise 2.2 db

27 Specifications Sensitivity/DANL ForBestSensitivity Use: ForBestSensitivity Use: N arrow estr esolution BW Minim um RF InputAttenuation SufficientVideo Filtering (Video BW <.01 R es BW )

28 Specifications D ynam ic R ange +30 dbm MAXIMUM POW ER LEVEL -10 dbm MIXER COM PRESSION LC D -DISPLAY RANGE 80 db INCREASING BANDW IDTH OR ATTENUATION MEASUREMENT RANGE 145 db -35 dbm SIGNAL/NOISE RANGE 105 db SIGNAL /3rd ORDER DISTORTION 80 db RANGE THIRD-ORDER DISTORTION SECOND-ORDER -45 dbm DISTORTION 0 dbc NOISE SIDEBANDS SIGNAL/2nd ORDER DISTORTION SIGNAL/NOISE 70 db RANGE SIDEBANDS 60 dbc/1kh z -115 dbm (1 kh z BW & 0 db ATTENUATION) MINIMUM NOISE FLO O R

29 Features M odulation M easurem ents:fft SweptFrequency Domain FFT Frequency Domain 10 db/ LIN M ARKER 1 kh z -26 dbc M ARKER 1 kh z -26 dbc CENTER 100 MHz SPAN 10 kh z CENTER 100 MHz SPAN 0 Hz

30 SPEC TR UM ANALYZER 9 kh z GHz Features Modulation Measurem ents:am /FM Detectorwith Speakers 8563A

31 SPEC TR UM ANALYZER 9 kh z GHz Features Noise M easurem ents:noise Marker& Video Averaging 8563A MKR MHz dbm /Hz AVG 10

32 Source Features Stim ulus R esponse:tracking G enerator Receiver DUT DUT RF in Spectrum Analyzer LO IF CRT Display TG out Tracking Adjust Tracking G enerator