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ZTEC Instruments

Our Presentation will Start Shortly. ZTEC Instruments. PXI Modular Oscilloscope Measurement Fundamentals Creston Kuenzi, Applications Engineer. ZTEC Instruments. PXI Modular Oscilloscope Measurement Fundamentals Creston Kuenzi, Applications Engineer. 1050!. Co-Host - PXISA.

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ZTEC Instruments

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  1. Our Presentation will Start Shortly ZTEC Instruments PXI Modular Oscilloscope Measurement Fundamentals Creston Kuenzi, Applications Engineer

  2. ZTEC Instruments PXI Modular Oscilloscope Measurement Fundamentals Creston Kuenzi, Applications Engineer

  3. 1050! Co-Host - PXISA • Manage PXI System Alliance, Founded in 1998 • About 70 Member Companies, Worldwide, Evolve PXI Specifications • Promote PXI www.pxisa.org Source: Prime Data, 2003 info@pxisa.org

  4. Co – Host - ZTEC • Based in Albuquerque, New Mexico • Manufacturer of innovative modular instrumentation products with a focus on PCI, PXI and VXI oscilloscopes • Applications include military, aerospace, manufacturing, and scientific research • Customers in over 25 Countries worldwide • Celebrating 10th year anniversary in 2006 The Leader in Modular Oscilloscopes

  5. Our Speaker – Creston Kuenzi • BS in Computer Engineering from Kansas State University – 1999 • Applications Engineer and Field Sales Engineer for National Instruments – 2000–2006 • Applications Engineer for ZTEC Instruments – 2006–Present

  6. Purpose Learn About PXI Modular Oscilloscope Measurement Capabilities in Order to Avoid Inaccurate or Misunderstood Results

  7. Agenda • Introduction to PXI Modular Oscilloscopes • Vertical-Axis Measurements • Horizontal-Axis Measurements • Frequency-Domain Measurements • Conclusions

  8. Introduction to PXI Modular Oscilloscopes

  9. Benchtop Oscilloscope High-Speed Digitizer What is a Modular Oscilloscope? Modular Oscilloscope Modular Oscilloscopes Combine the Power of a Benchtop Oscilloscope and the Flexibility of a High-Speed Digitizer

  10. PXI Modular Oscilloscope MultipleAcquisitionModes AdvancedTriggering Oscilloscope Memory On-boardSignalProcessing FlexibleSignal Conditioning Oscilloscope Interface A/D Converter DataMemory Input Signal Data Bus PXI Modular Oscilloscope Capabilities

  11. Oscilloscope Measurements

  12. Oscilloscope On-Board Measurement Variations • All True Oscilloscopes Have On-Board Measurements • These Measurements May Differ from Vendor to Vendor in Quantity, Name, and by the Algorithms Used • Today’s Discussion Will Show PXI ZTEC Scope On-Board Measurements • Some of These Same Measurements are Found on Other Oscilloscopes.

  13. Categories of Onboard Measurements • Vertical-Axis Measurements • Horizontal-Axis Measurements • Frequency-Domain Measurements

  14. Vertical-Axis Measurements

  15. Vertical-Axis Measurements • Analyze the vertical component of the applied signal • Most often describe a signal in terms of a voltage level • Can also correspond to current, power, or any other physical phenomena converted to voltage via a probe or transducer

  16. Common Vertical Measurements • Amplitude • Peak To Peak • Overshoot • Undershoot • Maximum • Minimum • Average • RMS • Etc

  17. Common Vertical Measurements

  18. Vertical-Axis Measurement Demo

  19. AC RMS, DC RMS, & Average • Average • Mean Value of Waveform • DC RMS • Direct Current (DC) Root Mean Square (RMS) • DC RMS = √(∑V2) / Number of points • Average Power of Signal • AC RMS • Alternating Current (AC) Root Mean Square (RMS) • AC RMS = √(∑(V-Vavg)2) / Number of points • Average Power of Signal Excluding DC Offset

  20. AC RMS, DC RMS, & Average

  21. AC RMS, DC RMS, & Average • Partial Cycles Can Return Inaccurate Measurements

  22. Avoiding Partial Cycle Problem • Acquire Longer Waveforms to Reduce Affect • Use Cycle RMS and Cycle Average Measurements • Use Gated Waveform Measurements

  23. AC RMS, DC RMS, & Average Demo

  24. Histogram Processing vs Waveform Processing • Histogram Processing • Generates a Histogram of the Voltage Values and Looks for a Single Characteristic • Very Fast Measurements but Less Accurate • Examples: Amplitude and PTPeak Measurements • Waveform Processing • Uses an Algorithm on Every Waveform Sample • More Accurate but Slower than Histogram Processing • Examples: Average, DC RMS, and AC RMS Measurements

  25. Histogram Processing vs Waveform Processing • Histogram of Voltage Values in an 8-bit Oscilloscope

  26. DC Power Supply Example Transient Signal Generated from DC Power Supply

  27. Horizontal-Axis Measurements

  28. Horizontal-Axis Measurements • Analyze the horizontal time axis of the applied signal • Usually describe the signal in terms of time • May also return a value expressed as a ratio, radians, or in Hertz

  29. Common Horizontal Measurements • Waveform Measurements • Period • Frequency • Edge Measurements • Crossing Time • Rise Time • Fall Time

  30. Common Horizontal Measurements

  31. Common Horizontal Edge Measurements

  32. Demo of Horizontal Measurements

  33. Noise Issue on Vertical Axis Causes Edge Problems • Vertical Noise Can Affect Horizontal Measurements

  34. Demo of Vertical Noise Causing Horizontal Measurement Error

  35. Telecommunications T1 Example T1 Signal Mask of Horizontal Measurements

  36. Frequency-Domain Measurements

  37. Frequency-Domain Measurements • Translate a time-domain waveform with a fast Fourier transform (FFT), and then measure the noise and distortion characteristics in the frequency domain. • Provide magnitude and phase characteristics versus frequency. • Reveal signal characteristics that cannot be seen within the time-domain.

  38. Fast Fourier Transform (FFT)

  39. FFT Windows • Used to increase spectral resolution in the frequency-domain. • The Rectangular Window provides the best frequency and worst magnitude resolution. It is almost the same as no window. • The Blackman-Harris Window provides the best magnitude and worst frequency resolution. • The Hamming Window provides better frequency and worse magnitude resolution than the Rectangular Window. It provides slightly better frequency resolution than the Hanning Window. • The Hanning Window provides better frequency and worse magnitude resolution than the Blackman Window. It provides slightly better magnitude frequency than the Hamming Window

  40. Demo of FFTs and Windows

  41. Common Frequency-Domain Measurements • Signal-to-Noise Ratio (SNR) is the ratio of the RMS amplitude of the fundamental frequency to the RMS amplitude of all non-harmonic noise sources. • Total Harmonic Distortion (THD) is the ratio of the RMS amplitude of the sum of the first nine harmonics to the RMS amplitude of the fundamental. • Spurious-Free Dynamic Range (SFDR) is the ratio of the RMS amplitude of the fundamental to the RMS amplitude of the largest spurious signal. • Signal-to-Noise and Distortion (SINAD) is the ratio of the RMS amplitude of the fundamental to the RMS amplitude of the sum of all noise and distortion sources. • Effective Number of Bits (ENOB) is another way of expressing SINAD. It provides a measure of the input signal dynamic range as if the signal were converted using an ideal ADC.

  42. Demo of Frequency-Domain Measurements

  43. High-Speed ADC Test Example FFT of ADC Two-Tone Distortion Test

  44. Summary • PXI Modular Oscilloscopes Have Powerful Onboard Measurements • The Three Categories on Measurements are Vertical-Axis, Horizontal-Axis, and Frequency Domain • Understanding These Measurements Will Help You Improve Your Tests and Avoid Problems

  45. Questions?

  46. Thank you! ZTEC Instruments www.ztecinstruments.com ZTEC Instruments 7715 Tiburon St. NE Albuquerque, NM 87109 Phone: (505) 342-0132 Fax: (505) 342-0222 isupport@ztec-inc.com PXI Systems Alliance www.pxisa.org 361 2nd Avenue, Suite 203 PO Box 1016 Niwot, Colorado 80544-1016 Phone: (303) 652-2585 Fax: (303) 652-1444 Info@pxisa.org

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