Basics of Oscilloscopes Presenter Name Presentation Name 1

Agenda • What Is an Oscilloscope • Why Do We Use an Oscilloscope • 4 Key Technical Aspects of Oscilloscopes You Should Know About. Hilton Hammond Basics of Oscilloscopes 2

What is an Oscilloscope? Volts • A Multi. Meter displays discreet measurements. Time – In a multimeter, the unknown quantity is sampled and converted to a known relative value at a rate of approximately 3 -4 times per second. Hilton Hammond Basics of Oscilloscopes 3

What is an Oscilloscope? Volts • An oscilloscope graphically plots the unknown quantity over time. Time “A picture is worth a thousand words!” Hilton Hammond Basics of Oscilloscopes 4

Why Do We Use an Oscilloscope • Analyze the integrity of waveforms • Sine • Square • Triangle • Ramp • DC Hilton Hammond Basics of Oscilloscopes 5

Why Do We Use an Oscilloscope • Looking for common anomalies • Noise • Glitch • Ringing • Jitter Hilton Hammond Basics of Oscilloscopes 6

Why Do We Use an Oscilloscope • Making common measurements • Voltage • Horizontal Time • Delta Time • Rise or Fall Time Hilton Hammond Basics of Oscilloscopes 7

Why Do We Use an Oscilloscope • Making Automatically calculated measurements • Frequency • Phase • Duty Cycle • d. B Level • Power Hilton Hammond Basics of Oscilloscopes 8

Why Do We Use an Oscilloscope • Perform Waveform Mathematics • A vs B (XY or Lissajous) • A x B • A + B • A - B Hilton Hammond Basics of Oscilloscopes 9

Key Technical Aspects: 1) Sample Rate & Bandwidth • Sample Rate • Time • An unknown signal is segmented in time. The voltage of the signal at each time segment is determined. This voltage value is stored to internal memory. Hilton Hammond Basics of Oscilloscopes 10

Key Technical Aspects: 1) Sample Rate & Bandwidth • Bandwidth = Maximum captured frequency, and is dependant on; – The Scope’s input circuit (The max frequency where the amplitude starts to decrease by more than -3 d. B. ) – Enough samples in order to accurately resolve and display a signal. Typically you need 10 samples period. • Too Few samples Results In… • An in-accurate representation of the true waveform (Aliasing) Hilton Hammond Basics of Oscilloscopes 11

Key Technical Aspects: 2) Memory • The amount of memory will effect the sample rate! • Consider: A sine wave of 1 second period. Sampled at a rate of 1 GSa/S (1 billion), how much memory will the Oscilloscope need? Hilton Hammond Basics of Oscilloscopes 12

Key Technical Aspects: 3) Triggering • Trigger is used to synchronize the waveform display at each display update/refresh. • It can also be used to capture specific “events” Hilton Hammond Basics of Oscilloscopes 13

Key Technical Aspects: 3) Advanced Functions • Scope. Record: Is used to look at a long term trend using high resolution waveform capture. • View All mode shows the “trend” • “Zoom in” to look at the individual cycles Hilton Hammond Basics of Oscilloscopes 14

Key Technical Aspects: 3) Advanced Functions • Replay: Automatically capture the last 100 screen updates. Go back in time to look at intermittent events or anomalies. “Its like having a video recorder capturing an event, press rewind to see what really happened!” Hilton Hammond Basics of Oscilloscopes 15

Oscilloscopes? • An oscilloscope is the engineers view into electronic/electrical signals. • It’s the best tool for troubleshooting signal anomalies or intermittent failures. “If you cannot see it, you cannot fix it” Hilton Hammond Basics of Oscilloscopes 16