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Agenda

Agenda. Overview: What is spectrum analysis? What measurements do we make? Theory of Operation: Spectrum analyzer hardware Specifications: Which are important and why? Appendix. Agenda. Overview Theory of Operation Specifications Summary Appendix. 8563A.

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Agenda

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  1. Agenda • Overview: • What is spectrum analysis? • What measurements do we make? • Theory of Operation: • Spectrum analyzer hardware • Specifications: • Which are important and why? • Appendix Spectrum Analyzer Basics

  2. Agenda • Overview • Theory of Operation • Specifications • Summary • Appendix Spectrum Analyzer Basics

  3. 8563A SPECTRUM ANALYZER 9 kHz - 26.5 GHz Overview What is Spectrum Analysis? Spectrum Analyzer Basics

  4. Overview Types of Tests Made . Modulation Noise Distortion Spectrum Analyzer Basics

  5. Overview Frequency versus Time Domain Amplitude (power) frequency time Time domain Measurements Frequency Domain Measurements Spectrum Analyzer Basics

  6. Overview Different Types of Analyzers Fourier Analyzer Parallel filters measured simultaneously A LCD shows full spectral display f f f 2 1 Spectrum Analyzer Basics

  7. f f 2 1 Overview Different Types of Analyzers Swept Analyzer Filter 'sweeps' over range of interest A LCD shows full spectral display f Spectrum Analyzer Basics

  8. Agenda • Overview • Theory of Operation • Specifications • Summary • Appendix Spectrum Analyzer Basics

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

  10. MIXER + f f f - f sig sig LO LO f sig f f sig LO f LO Theory of Operation Mixer input RF IF LO Spectrum Analyzer Basics

  11. IF FILTER Input Spectrum IF Bandwidth (RBW) Display Theory of Operation IF Filter Spectrum Analyzer Basics

  12. DETECTOR amplitude Theory of Operation Detector "bins" Positive detection: largest value in bin displayed Negative detection: smallest value in bin displayed Sample detection: last value in bin displayed Spectrum Analyzer Basics

  13. Theory of Operation Video Filter VIDEO FILTER Spectrum Analyzer Basics

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

  15. f s f f f - f f LO + LO s LO s f s f s f IF f LO 0 1 2 3 (GHz) Theory of Operation How it all works together Signal Range LO Range 0 1 2 3 (GHz) IF filter 0 1 5 6 4 2 3 mixer detector 3.6 6.5 input 3.6 sweep generator A LO f 6 5 LCD display (GHz) 4 3 3.6 6.5 Spectrum Analyzer Basics

  16. 8563A SPECTRUM ANALYZER 9 kHz - 26.5 GHz Theory of Operation Front Panel Operation Primary functions (Frequency, Amplitude, Span) Softkeys Control functions (RBW, sweep time, VBW) Numeric keypad RF Input Spectrum Analyzer Basics

  17. Agenda • Overview • Theory of Operation • Specifications • Summary • Appendix Spectrum Analyzer Basics

  18. 8563A SPECTRUM ANALYZER 9 kHz - 26.5 GHz Specifications • Frequency Range • Accuracy: Frequency & Amplitude • Resolution • Sensitivity • Distortion • Dynamic Range Spectrum Analyzer Basics

  19. Specifications Frequency Range Low frequencies for baseband and IF Measuring harmonics 50 GHz and beyond! Spectrum Analyzer Basics

  20. Specifications Accuracy Absolute Amplitude in dBm Relative Amplitude in dB Frequency Relative Frequency Spectrum Analyzer Basics

  21. Specifications Accuracy: 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") Frequency Spectrum Analyzer Basics

  22. = = = = 260 Hz 4000 Hz 450 Hz 10 Hz 4720 Hz + _ Specifications Accuracy: Frequency Readout Accuracy Example Single Marker Example: 2 GHz 400 kHz span 3 kHz RBW 9 -7 Calculation: (2x10 Hz) x (1.3x10 /yr.ref.error) 1% of 400 kHz span 15% of 3 kHz RBW 10 Hz residual error Total = Spectrum Analyzer Basics

  23. Relative Amplitude in dB Specifications Accuracy: Relative Amplitude Accuracy • Display fidelity • Frequency response • RF Input attenuator • Reference level • Resolution bandwidth • Display scaling Spectrum Analyzer Basics

  24. Relative Amplitude in dB Specifications Accuracy: Relative Amplitude Accuracy - Display Fidelity • Applies when signals are not placed at the same reference amplitude • Display fidelity includes • Log amplifier or linear fidelity • Detector linearity • Digitizing circuit linearity • Technique for best accuracy Spectrum Analyzer Basics

  25. Specification: ± 1 dB Specifications Accuracy: Relative Amplitude Accuracy - Freq. Response Signals in the Same Harmonic Band +1 dB 0 - 1 dB BAND 1 Spectrum Analyzer Basics

  26. Relative Amplitude in dB Specifications Accuracy: Relative Amplitude Accuracy • RF Input attenuator • Reference level • Resolution bandwidth • Display scaling Spectrum Analyzer Basics

  27. Specifications Accuracy: Absolute Amplitude Accuracy Absolute Amplitude in dBm • Calibrator accuracy • Frequency response • Reference level uncertainty Spectrum Analyzer Basics

  28. Specifications Resolution What Determines Resolution? Resolution Bandwidth Residual FM RBW Type and Selectivity Noise Sidebands Spectrum Analyzer Basics

  29. Specifications Resolution: Resolution Bandwidth 3 dB Detector Mixer 3 dB BW Input Spectrum IF Filter/ Resolution Bandwidth Filter (RBW) LO Sweep RBW Display Spectrum Analyzer Basics .

  30. Filter Demo - Theory: IF filter One signal - change RBW to see how display traces out shape of IF filter 8447F Amplifier out in Spectrum Analyzer Setup fc=170 Mhz RBW=1 MHz VBW=300 kHz span=10 MHz Spec An Signal Generator Setup ESG-D4000A Sigl Gen Bandpass filter (center frequency = 170 MHz) f=170 MHz, A=-25 dBm On ESG-D4000A Sigl Gen Off Power Splitter (used as combine) Spectrum Analyzer Basics

  31. Specifications Resolution: Resolution Bandwidth 10 kHz RBW 3 dB 10 kHz Spectrum Analyzer Basics .

  32. Filter Demo #4 - Resolution: RBW Two equal-amplitude signals spaced 10 kHz apart - change RBW to 10 kHz to see 3 dB 'dip' 8447F Amplifier out in Spectrum Analyzer Setup fc=170 Mhz RBW=30 kHz VBW=1 kHz span=100 kHz Spec An 1 Signal Generator Setup ESG-D4000A Sigl Gen f=170 MHz, A=-25 dBm On ESG-D4000A Sigl Gen On 2 Signal Generator Setup f=170.01 MHz, A=-25 dBm Power Splitter (used as combiner) Spectrum Analyzer Basics

  33. Specifications Resolution: RBW Type and Selectivity 3 dB 3 dB BW 60 dB 60 dB BW 60 dB BW Selectivity = 3 dB BW Spectrum Analyzer Basics

  34. Specifications Resolution: RBW Type and Selectivity RBW = 1 kHz Selectivity 15:1 RBW = 10 kHz 3 dB distortion products 7.5 kHz 60 dB 60 dB BW = 15 kHz 10 kHz 10 kHz Spectrum Analyzer Basics

  35. Specifications Resolution: Residual FM Residual FM "Smears" the Signal Spectrum Analyzer Basics

  36. Specifications Resolution: Noise Sidebands Phase Noise Noise Sidebands can prevent resolution of unequal signals Spectrum Analyzer Basics

  37. Penalty For Sweeping Too Fast Is An Uncalibrated Display Specifications Resolution: RBW Determines Measurement Time Swept too fast Spectrum Analyzer Basics

  38. ANALOG FILTER DIGITAL FILTER RES BW 100 Hz SPAN 3 kHz Specifications Resolution: Digital Resolution Bandwidths Typical Selectivity Analog 15:1 Digital 5:1 Spectrum Analyzer Basics

  39. Detector Mixer RF Input RES BW Filter LO Sweep Specifications Sensitivity/DANL A Spectrum Analyzer Generates and Amplifies Noise Just Like Any Active Circuit Spectrum Analyzer Basics

  40. Specifications Sensitivity/DANL Effective Level of Displayed Noise is a Function of RF Input Attenuation signal level 10 dB Attenuation = 20 dB Attenuation = 10 dB Signal-To-Noise Ratio Decreases as RF Input Attenuation is Increased Spectrum Analyzer Basics

  41. 10 dB 10 dB Specifications Sensitivity/DANL: IF Filter (RBW) Displayed Noise is a Function of IF Filter Bandwidth 100 kHz RBW 10 kHz RBW 1 kHz RBW Decreased BW = Decreased Noise Spectrum Analyzer Basics

  42. Specifications Sensitivity/DANL: VBW Video BW Smoothes Noise for Easier Identification of Low Level Signals Spectrum Analyzer Basics

  43. Specifications Sensitivity/DANL Sensitivity is the Smallest Signal That Can Be Measured 2.2 dB Signal Equals Noise Spectrum Analyzer Basics

  44. Specifications Sensitivity/DANL For Best Sensitivity Use: • Narrowest Resolution BW • Minimum RF Input Attenuation • Sufficient Video Filtering(Video BW < .01 Res BW) Spectrum Analyzer Basics

  45. Frequency Translated Signals Resultant Signal To Be Measured Mixer Generated Distortion Specifications Distortion Mixers Generate Distortion Spectrum Analyzer Basics

  46. Specifications Distortion Most Influential Distortion is the Second and Third Order < -40 dBc < -50 dBc < -50 dBc Two-Tone Intermod Harmonic Distortion Spectrum Analyzer Basics

  47. 3 3 Power in dB 2f - f f f 2f - f 2 2 1 1 2 1 2 3 Power in dB Second Order: 2 dB/dB of Fundamental Third Order: 3 dB/dB of Fundamental 2f 3f f Specifications Distortion Distortion Products Increase as a Function of Fundamental's Power Third-order distortion Second-order distortion Two-Tone Intermod Harmonic Distortion Spectrum Analyzer Basics

  48. 1 dB Specifications Distortion Relative Amplitude Distortion Changes with Input Power Level 1 dB 20 dB 21 dB 3 dB 2 dB f 3f 2f Spectrum Analyzer Basics

  49. INPUT - ATTENUATOR SETTING dBm POWER AT MIXER = Specifications Distortion Distortion is a Function of Mixer Level 0 . -20 Second Order -40 DISTORTION, dBc -60 -80 Third Order -100 -60 -30 0 +30 TOI Spectrum Analyzer Basics

  50. 2 1 Specifications Distortion Distortion Test: Is it Internally or Externally Generated? RF INPUT ATTENUATOR IF GAIN Watch Signal on Screen: Change Input Attn by 10 dB • No change in amplitude = distortion is part of input signal (external) • Change in amplitude = at least some of the distortion is being generated inside the analyzer (internal) Spectrum Analyzer Basics

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