Agenda. Spectrum Analyzer Basics

Transcription

1 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 Su m mary Appendix

2 Agenda Overview Theory of Operation Specifications Features Sum mary Appendix

3 SPE CT R U M AN A LYZ E R 9 k Hz G H z Overview What is Spectrum Analysis? 8563A

4 Overview Types of Tests Made. Modulation Noise Distortion

5 Overview Frequency versus Time Do main Amplitude (power) frequency time Time domain Measurements Frequency Domain Measurements

6 Overview Different Types of Analyzers Fourier Analyzer A Parallelfilters m easured simultaneously LCD shows full spectral display f 1 f 2 f

7 Overview Different Types of Analyzers Swept Analyzer A Filter'sweeps' overrange ofinterest LCD shows full spectral display f 1 f 2 f

8 Agenda Overview Theory of Operation Specifications Features Sum mary Appendix

9 Theory of Operation Spectrum Analyzer Block Diagram RF input attenuator mixer IF gain IF filter detector Input signal Pre-Selector Or Low Pass Filter local oscillator Log Amp video filter sweep generator Crystal Reference CRT display

10 Theory of Operation Mixer input MIXER f sig RF IF LO f sig f LO - f sig f LO f LO + f sig f LO

11 Theory of Operation IF Filter IF FILTE R Input Spectrum IF Bandwidth (RB W) Display

12 Theory of Operation Detector DETECTOR amplitud e "bins" Positive detection: largest value in bin displayed Negative detection: smallest value in bin displayed Sample detection: last value in bin displayed

13 Theory of Operation Video Filter VIDE O FILTE R

14 Theory of Operation Other Components LO RF INPUT ATTENUATOR IF GAIN SWEEP GEN frequency LCD DISPLAY

15 Theory of Operation How itall works together f s Signal Range LO Range (GHz) f - LO f s f LO f LO +f s f s IF filter input mixer f s detector 3.6 sweep generator f IF A LO f LO (GHz) LCD display (GHz) f

16 SPE CT R U M AN A LYZ E R 9 k Hz G H z Softkeys Theory of Operation Front PanelOperation Primary functions (Frequency, Amplitude, Span) 8563A Controlfunctions (RB W, sweep time, VB W) RF Input Numeric keypad

17 Agenda Overview Theory of Operation Specifications Features Sum mary Appendix

18 SPE CT R U M AN A LYZ E R 9 k Hz G H z Specifications 8563A Frequency Range Accuracy:Frequency & Amplitude Resolution Sensitivity Distortion Dynamic Range

19 Specifications Frequency Range Low frequencies for for baseband and and IF IF Measuring harmonics GHz and and beyond!

20 Specifications Accuracy Absolute Amplitude in dbm Relative Amplitude in db Frequency Relative Frequency

21 Specifications Accuracy: Frequency Readout Accuracy Typical datasheetspecification: Spans < 2 M Hz: +_ (freq. readout xfreq. ref. accuracy + 1% offrequency span + 15 % of resolution band width + 10 Hz "residual error") Frequency

22 Specifications Accuracy: Frequency Readout Accuracy Example Single Marker Example: 2 G Hz 400 khz span 3 khz RB W 9-7 Calculation: (2x10 Hz) x (1.3x10 /yr.ref.error) 1% of400 khz span 15 % of 3 khz RB W 10 Hz residual error Total = = = = = +_ 260 Hz 4000 Hz 450 Hz 10 Hz 4720 Hz

23 Specifications Accuracy: Relative Amplitude Accuracy Display fidelity Frequency response RF Input attenuator Reference level Resolution bandwidth Display scaling Relative Amplitude in db

24 Specifications Accuracy: Relative Amplitude Accuracy - Display Fidelity Applies when signals are not placed atthe same reference amplitude Display fidelityincludes Log amplifier orlinear fidelity Detectorlinearity Digitizing circuitlinearity Technique for bestaccuracy Relative Amplitude in db

25 Specifications Accuracy: Relative Amplitude Accuracy - Freq. Response Signals in the Sa me Harmonic Band +1 db 0-1 db BAND 1 Specification: ± 1 db

26 Specifications Accuracy: Relative Amplitude Accuracy RF Input attenuator Reference level Resolution bandwidth Display scaling Relative Amplitude in db

27 Specifications Accuracy: Absolute Amplitude Accuracy Absolute Amplitud e in dbm Calibrator accuracy Frequency response Reference level uncertainty

28 Specifications Resolution What Determines Resolution? Resolution Bandwidth Residual FM RB W Type and Selectivity Noise Sidebands

29 Specifications Resolution: Resolution Bandwidth Mixer 3 db B W 3 db Detector Input Spectrum LO IF Filter/ Resolution Bandwidth Filter (RB W) Sweep RBW Display

30 Demo -Theory:IF filter 8447F Amplifier One signal-change RBW to see how display traces out shape of IF out in Spec An filterfilter Spectrum Analyzer Setup fc=170 Mhz RBW=1 MHz VB W=300 khz span=10 MHz ES G-D4000A Sigl Gen ES G-D4000A Sigl Gen Signal Generator Setup f=170 M Hz, A=-25 dbm On Bandpass filter (centerfrequency = 170 MHz) Off Power Splitter (used as combine)

31 Specifications Resolution: Resolution Bandwidth 10 khz RB W 3 db 10 khz

32 De mo #4 - Resolution: RB W Spec An 8447F Amplifier out in T w o equal-a m plitude signals spaced 10 khz apart-change RBW to 10 khz to see 3 db 'dip' Spectrum Analyzer Setup fc=170 Mhz RBW=30 khz VB W=1 khz span=100 khz ES G-D4000A Sigl Gen ES G-D4000A Sigl Gen 2 Signal Generator Setup f= M Hz, A=-25 dbm On 1 Signal Generator Setup f=170 M Hz, A=-25 dbm On Filter Power Splitter (used as combiner)

33 Specifications Resolution: RB W Type and Selectivity 3 db 3 db B W 60 db 60 db BW Selectivity = 60 db B W 3 db B W

34 Specifications Resolution: RB W Type and Selectivity RB W = 1 khz Selectivity 15:1 R B W = 10 khz 3 db 7.5 khz distortion products 60 db 60 db B W = 15 khz 10 khz 10 khz

35 Specifications Resolution: Residual FM ResidualFM "Smears" the Signal

36 Specifications Resolution: Noise Sidebands Phase Noise Noise Sidebands can prevent resolution of unequal signals

37 Specifications Resolution: RB W Determines Measurement Time Swept too fast Penalty For Sweeping Too Fast Is An Uncalibrated Display

38 Demo - Specs:Resolution: RBW Determines Measurement Time Spec An 8447F Amplifier out ES G-D4000A Sigl Gen ES G-D4000A Sigl Gen in 2 Signal Generator Setup f= M Hz, A=-25 dbm On Spectrum Analyzer Setup fc=170 Mhz RBW=30 khz VB W=1 khz span=100 khz 1 Signal Generator Setup f=170 M Hz, A=-25 dbm On Filter Power Splitter (used as combiner) Two equal-a mplitude signals spaced 10 khz apart-change sweep time to sho w 'uncalibrated' message, & signal shifted down and to the right

39 Specifications Resolution: Digital Resolution Bandwidths ANALOG FILTER Typical Selectivity Analog 15:1 Digital 5:1 DIGITAL FILTER R ES B W 100 Hz SPAN 3 khz

40 Specifications Sensitivity/DA NL RF Input Mixer RES BW Filter Detector LO Sweep A Spectrum Analyzer Generates and Amplifies Noise Just Like Any Active Circuit

41 Specifications Sensitivity/DA NL Effective Level of Displayed Noise is a Function of RF Input Attenuation signal level 10 db Attenuation = 10 db Attenuation = 20 db Signal-To-Noise Ratio Decreases as RF Input Attenuation is Increased

42 De mo #6 - Sensitivity/DA NL - SN R decreases as RF inputattn increases Spec An 8447F Amplifier out in Spectrum Analyzer Setup fc=170 Mhz RBW=100 khz VB W=10 khz span=10 MHz Smallsignal-change Input attenuation to see SN R decrease ES G-D4000A Sigl Gen ES G-D4000A Sigl Gen Signal Generator Setup f=170 M Hz, A=-90 dbm On Filter Off Power Splitter (used as combiner)

43 Specifications Sensitivity/DANL: IF Filter(RB W) Displayed Noise is a Function ofif Filter Bandwidth 100 khz RB W 10 db 10 db 10 khz RB W 1 khz RB W Decreased B W = Decreased Noise

44 Demo -Specs:Sensitivity/DANL:IF Filter Spec An 8447F Amplifier out in Spectrum Analyzer Setup fc=170 Mhz RBW=100 khz VB W=10 khz span=10 MHz Smallsignal-change RBW to see Noise level decrease ES G-D4000A Sigl Gen ES G-D4000A Sigl Gen Signal Generator Setup f=170 M Hz, A=-90 dbm On Filter Off Power Splitter (used as combiner)

45 Specifications Sensitivity/DANL: VB W Video BW S moothes Noise for Easier Identification of Low LevelSignals

46 Demo -Theory:Video Filter 8447F Amplifier out in Smallsignalin noise - change VBW to see smooth out Spec An ES G-D4000A Sigl Gen ES G-D4000A Sigl Gen Spectrum Analyzer Setup fc=170 Mhz RBW=100 khz VB W=100 khz span=10 MHz Detector=SP Signal Generator Setup f=170 M Hz, A=-100 db m On Filter Off Power Splitter (used as combiner)

47 Specifications Sensitivity/DA NL Sensitivity isthe Smallest Signal That Can Be Measured Signal Equals Noise 2.2 db

48 Specifications Sensitivity/DA NL For BestSensitivity Use: For BestSensitivity Use: Narrowest Resolution B W Minimu m RF Input Attenuation Sufficient Video Filtering (Video BW <.01 Res B W)

49 Specifications Distortion Mixers Generate Distortion Frequency Translated Signals Resultant Signal To Be Measured Mixer Generated Distortion

50 Specifications Distortion Most Influential Distortion is the Second and Third Order < -50 dbc < -40 dbc < -50 dbc Two-Tone Intermod Harmonic Distortion

51 Specifications Distortion Distortion Products Increase as a Function of Fundamental'sPower Power in db 2f -f 3 Second Order:2 db/db of Fundamental Third Order: 3 db/db of Fundamental f Two-Tone Intermod f 3 2f -f 2 1 Power in db Third-order distortion Second-order distortion 2 f 2f 3f Harmonic Distortion 3

52 Demo - Specs:Distortion - Distortion products increase as a function of 8447F fundamental s Amplifier power out Spec An ES G-D4000A Sigl Gen ES G-D4000A Sigl Gen in Off Spectrum Analyzer Setup fc=340 MHz cf step=170 MHz RBW=1 MHz VB W=300 khz span=200 MHz Signal Generator Setup f=170 M Hz, A=+10 dbm On Signal to create har m o nic distortion products - change funda mental's po wer levelto see appropriate changes in harmonics Filter Power Splitter (used as combiner)

53 Specifications Distortion Relative A m plitude Distortion Changes with Input Power Level 1 db 21 db 1 db 20 db 2 db 3 db f 2f 3f

54 . Specifications Distortion 0 Distortion is a Function of Mixer Level DIST O RTIO N, dbc Second Order Third Order TOI POWER AT MIXER = INPUT - ATTENUATO R SETTING dbm

55 Specifications Distortion Distortion Test: IsitInternally or ExternallyGenerated? RF INPUT ATTENUATOR IF GAIN 1 Change Input Attn by 10 db 2 W atch Signalon Screen: No change in a mplitude = distortion is part of input signal (external) Change in am plitude = at least some ofthe distortion is being generated inside the analyzer (internal)

56 Specifications Dynamic Range Dynamic Range

57 . Specifications Dynamic Range Signal-to-Noise Ratio Can Be Graphed 0 SIGNAL-TO-NOISE RATIO, dbc Displayed Noise in ina 1 khz khz RB RB W -100 Displayed Noise in in a Hz Hz RBW POWER AT MIXER = INPUT - ATTENUATO R SETTING dbm

58 .. Specifications Dynamic Range Dynamic Range Can Be Presented Graphica ly SIGNAL-TO-NOISE RATIO, dbc Maximu Maximu m 2nd 2nd Order Order Dynamic Dynamic Range Range DISPLAYED NOISE (1 khz RB W) Maximum Maximum 3rd 3rd Order Order Dynamic Dynamic Range Range SECOND ORDER THIRD ORDER -100 Optimum Optimum Mixer Mixer Levels Levels TOI SOI POWER AT MIXER = INPUT - ATTENUATO R SETTING dbm

59 Specifications Dynamic Range Dynamic Range for Spur Search Depends on Closeness to Carrier Dyna mic Range Limited By Noise Sidebands dbc/hz Dyna mic Range Limited By Co mpression/noise Noise Sidebands Displayed Average Noise Level 100 khz to 1 M Hz

60 Specifications Dynamic Range Actual Dynamic Range isthe Minimum of: Maximu m dynamic range calculation Maximu m dynamic range calculation Calculated from: distortion sensitivity Noise sidebands atthe offset frequency Noise sidebands atthe offset frequency

61 Specifications Dynamic Range +30 dbm MAXIMUM POWER LEVEL -10 db m MIXER CO M P RESSION LCD-DISPLAY RANGE 80 db INCREASING BAND WIDTH OR ATTENUATION MEASUREMENT RANGE 145 db SIG N AL/N OISE RANGE 105 db -35 db m THIRD-ORDER DISTORTION SECOND-ORDER -45 db DISTO m RTION 0 dbc NOISE SIDEBANDS SIGNAL /3rd ORDE R DISTO RTION 80 db RANGE SIGNAL/ 2nd ORDER DISTO RTION SIGNAL/NOISE 70 db RANGE SIDE B A N D S 60 dbc/1khz -115 db m (1 khz B W & 0 db ATTE N U ATION) MINIM U M N OISE FLO O R

62 Agenda Overview Theory of Operation Specifications Features Sum mary Appendix

63 SPE CT R U M AN A LYZ E R 9 k Hz G H z Features 8563A Modulation Measurements time domain FFT AM/FM detector time-gating Basic Operation remote operation markers limitlines Noise Measurements noise marker averaging Stimulus Response Measurements tracking generator

64 SPE CT R U M AN A LYZ E R 9 k Hz G H z Features Basic Operation: Remote Operation, Markers & Limit Lines 8563A MARKER MHz db

65 D e m o #9 - Features: Basic Operation 8447F Amplifier Sho w use of %AM markers under [Meas User] hardkey out Spec An in Spectrum Analyzer Setup fc=170 Mhz RBW=1 khz VB W=1 khz span=100 khz ES G-D4000A Sigl Gen ES G-D4000A Sigl Gen Signal Generator Setup f=170 M Hz, A=-25 dbm 20 %A M, 1kHz On Filter Off Power Splitter (used as combiner)

66 Features Modulation Measurements: Time Domain LIN MARKER 10 msec X CENTER 100 MHz SPAN 0 Hz RES BW 1 MHz VB W 3 MHz SWP 50 msec

67 De mo #10 - Features: Mod Meas'ts: Time Domain Spec An 8447F Amplifier out in A M signal-look atin zero-span Spectrum Analyzer Setup fc=170 Mhz RBW=3 MHz VB W=1 MHz span= zero ES G-D4000A Sigl Gen ES G-D4000A Sigl Gen On Signal Generator Setup f=170 M Hz, A=-25 dbm 20 %A M, 1kHz Filter Off Power Splitter (used as combiner)

68 Features Modulation Measurements: FFT Swept Frequency Domain FFT Frequency Domain 10 db/ LIN MARKER 1 khz -26 dbc MARKER 1 khz -26 dbc CENTER 100 MHz SPAN 10 khz CENTER 100 MHz SPAN 0 Hz

69 De mo #11 - Features: Mod meas: FFT 8447F Amplifier A M signal-look at in zero-span, turn on FFT with stop frequency = 4 khz out Spec An in Spectrum Analyzer Setup fc=170 Mhz RBW=3 MHz VB W=1 MHz span= zero ES G-D4000A Sigl Gen ES G-D4000A Sigl Gen Signal Generator Setup f=170 M Hz, A=-25 dbm 20 %A M, 1kHz On Filter Off Power Splitter (used as combiner)

70 Features Modulation Measurements: FFT CENTER 100 MHz SPAN 50 khz

71 SPE CT R U M AN A LYZ E R 9 k Hz G H z Features Modulation Measurements: AM/FM Detector with Speakers 8563A

72 Features Modulation Measurements: Time-Gating Time Division Multiple Access (TD M A) Amplitude user # Channel Number Ti me Ti meslot Frequency 1

73 Features Modulation Measurements: Time-Gating Time-Gated Measurements in the Frequency Do main "time gating" Envelope Detector GATE time Video Filter Frequency

74 SPE CT R U M AN A LYZ E R 9 k Hz G H z Features Noise Measurements: Noise Marker & Video Averaging 8563A MKR MHz dbm/hz AVG 10

75 Source Features Stimulus Response: Tracking Generator Receiver DUT RF in Spectrum Analyzer IF CRT Display DUT LO TG out Tracking Adjust Tracking Generator

76 Agenda Overview Theory of Operation Specifications Features Sum mary Appendix

77 Agilent Spectrum Analyzer Product Families 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 856XEC family 30 Hz up to 50 G Hz high performance color display W-CD M A test set fast, digital 1 Hz RB W family DC to 2.65 GHz vector signal analyzers digital modulation complex,time-varying signals spectrum and time waveform analysis

78 Agenda Overview Theory of Operation Specifications Features Sum mary Appendix

79 Specifications Accuracy: Other Sources of Uncertainty Mis match (RF input portnot exactly 50 ohms) Co mpression due to overload (high-level input signal) Distortion products Amplitudes below the log am plifier range Signals near noise Noise causing amplitude variations Two signals incom pletely resolved

80 Specifications Dynamic Range Calculated Maximum Dynamic Range MDR = 2/3 (DANL -TOI) 3 MDR = 1/2 (DANL - SOI) 2 Where TOI = Mixer Level -dbc/2 SOI = Mixer Level -dbc Optimu m Mixer Level = DANL - MDR Attenuation = Signal - Optim u m Mixer Level

81 Specifications Dynamic Range Example Calculation MDR = 2/3 [(-115) -(+5)] 3 = -80 dbc (1 khz RB W) Where TOI = (-30) -(-70)/2 = + 5 db m Optimu m Mixer Level = (-115) -(-80) = -35 dbm Attenuation = (0) -(-35) = +35 dbm

82 Demo -Theory:Detector 8447F Amplifier out in No signal(just noise) - change detector modes to see difference Spec An ES G-D4000A Sigl Gen Spectrum Analyzer Setup fc=170 Mhz RBW=100 khz VB W=100 khz span=10 MHz Detector=SP Filter ES G-D4000A Sigl Gen Power Splitter (used as combiner)

83