Fluke 190-204 Oscilloscope • • • • • • 4 Isolated Channels 200 Mhz Bandwidth CAT III 1000 CAT IV 600 Rated 2.5 GS/s sample rate Connect-and-View™ IP-51 Rated Oscilloscopes • • Electrical Signals are measured in three domains 110.56 Vac • An osciloscope displays a signal amplitude change over time Volts Y axis, Amplitude (Volts, dB) A multimeter precisely measures a signals amplitude time • A spectrum analyzer displays a signal power level (amplitude) with respect to frequency dB X axis, time (Seconds) Frequency What is a multimeter? A Multimeter accurately displays discreet Volts, Ohms and Amp measurements. Amplitude in Volts • • Time in Seconds A typical multimeter uses an integrating ADC to convert an unknown voltage – An integrating capacitor is charged for a precise time span, then discharged. – The discharge time is proportionate to the unknown signal charging the integrator. – The longer the integration time, the higher the resolution, therefore more accurate the measurement becomes. Accuracies as low as 10’s of parts per million (0.001 %) can be achieved What is an Oscilloscope? An Oscilloscope graphically plots signals over time – The oscilloscope using high speed A to D conversion, samples the unknown input as fast as possible then graphically plots the unknown samples over time Amplitude in Volts • Time in Seconds “A picture is worth a thousand words!” DMM or Oscilloscope? • • A multimeter, presents a single precise measured value An oscilloscope presents a graphical representation of a signal change over time. – To obtain precise measurements, the typical DMM converts the unknown input at a rate of 5 or 10 times per second – To accurately represent a signal change over time, an oscilloscope can sample the unknown input up to 2.5 billion times per second (or faster) Digital Storage Oscilloscope Lf Hf Micro Processor Ch A 2.5 GSa/s A/D Memory Optional Ch Isolation Input Coupling •AC or DC Amplitude Control •Attenuation •Amplification Channel Isolation •Up to 1000 Volt isolation •Available on some scopes A to D Conversion •Real time •Up to 2.5 GSa/s Triggering •Edge •Edge Delay •Pulse Width •N-Cycle System Control •Sample Storage •Measure functions •Graphics processing •User interface Input Coupling • Input coupling determines what is passed on to the signal conditioning circuit – AC, Passes AC component only – DC, Passes both AC and DC components of the signal Applied Input Resultant Output DC Coupling Gnd Ref AC & DC Signal Components Gnd Ref AC Coupling Gnd Ref AC Signal Component, DC is blocked by capacitor Display Amplitude Control • Controls the vertical span of the displayed signal, adjusted in volts per vertical display division – mV increases sensitivity – V decreases sensitivity Vertical Sensitivity (V/Div) Amplitude display range mV Gnd Ref Pressing mV increases vertical sensitivity Gnd Ref V Gnd Ref Pressing V deceases vertical sensitivity Analog to Digital Conversion • The unknown signal is applied to the analog to digital converter (A/D). – The A/D process divides the signal into segments at specified time intervals. – At each time interval the voltage of the signal is determined and stored into memory Storage Memory 1 2 3 4 5 6 . . . . . . . A to D Conversion Gnd Ref Gnd Ref mS/Div S/Div Horizontal Time base (s/Div) Sampling clock interval time Horizontal resolution 1000 time Sample Rate • A digital storage oscilloscope contains a fixed amount of memory points – The more memory, the higher the cost and the longer it takes to fill up over a complete acquisition cycle – The fewer memory points the lower the resolution, the displayed signal time span and frequency bandwidth • The sample rate will increase or decrease relative to the amount of memory and maximum sample rate • It will automatically adjust the sample rate from its maximum at the fastest time base setting (nano seconds/div) to a slower sample rate at the slower time base settings (example, milli seconds/div) Memory Depth Sample Rate & Memory gS S ns Min Time base Digital Oscilloscope Aliasing • If the acquisition rate is much slower than the frequency of the measured signal Aliasing can occur • Aliasing displays incorrect signals Actual Signal Signal observed when Aliasing occurs A/D – Glitch Detection • Glitch Detect – At slow time base settings/ sampling intervals the A/D can miss glitches – Over sampling captures min and max sample points, preventing aliasing and displaying glitches Digitized Signal Actual Signal Display Pixels Displayed Max Sample Over Sampling Glitch Detect •The Min & Max samples displayed in each column Displayed Min Sample Oscilloscope Bandwidth • Bandwidth, determines the highest signal frequency the oscilloscope can accurately reproduce – The maximum frequency is usually determined by measuring the point at which the amplitude decreases as frequency increases by no more than -3 db’s (30% change) – Bandwidth is also dependent on sampling rate Test Signal Volume Frequency 1 Perceived Volume Frequency 2 Frequency 3 Triggering • Triggering, synchronizes the waveform display process every time the waveform is refreshed or displayed. Composite image of “UnTriggered” scope 1 4 Acquisition cycles 3 2 Triggered, resulting in stable display T Triggering Techniques • Oscilloscopes use several techniques to trigger on unknown signals V level – Edge, a specific voltage level set relative to either a rising or falling edge. – Pulse Width, specifies both a specific voltage level relative to an edge, plus a time interval between the rise and falling edges (or visa versa). – Automatic Connect&View: • As implied, connect then view, as simple as that! • Eliminates need to continuously adjust the scope vertical sensitivity, horizontal time and trigger settings time V level Trigger V/Div Time/Div Oscilloscope Isolation Ref A Ref B AC to DC Power Adapter, specially designed to meet CAT II 1000V/ CAT III 600V Safety rating • • The ScopeMeter input connectors are insulated to prevent against exposure to electrical voltages The input power adapter is isolated from earth ground, allowing for floating measurements Isolated adapter DC Out • • A typical bench oscilloscope uses metal BNC connectors and metal chassis components, potentially exposing the user to hazardous voltages. To protect against electric shock the bench oscilloscope is connected directly to earth ground via wall outlet. Channel Isolation CH A Signal Input Common reference tied to earth ground CH A CH B Referen CH A Referen ce Input Signal ce Input Input CAT II 1000 V/ CAT III 600V Isolation • Bench oscilloscope with exposed metal BNC connectors and common input references, for safety reasons are tied to earth ground • Fluke 190 series portable oscilloscope with insulated BNC input connectors isolated from earth ground with isolated input references CH B Signal Input CH B Signal Input The Fluke ScopeMeter test tools provide a safe means to measure floating differential voltages Using the 190-204 Oscilloscope • Input Connections – BNC Connectors are 300V CAT IV – Fluke 10:1 Probes provide 1000V CAT III 600V CAT IV Using the 190-204 Oscilloscope • Resetting the 190-204 to factory settings Using the 190-204 Oscilloscope • Hiding Labels and Key Illumination meaning Using the 190-204 Oscilloscope • Probe Settings Using the 190-204 Oscilloscope • Selecting Input Channels Using the 190-204 Oscilloscope • Connect-and-View™ Using the 190-204 Oscilloscope • Automatic Measurements Using the 190-204 Oscilloscope • Average, Persistance, and Glitch Capture Using the 190-204 Oscilloscope • Displaying Glitches and suppressing High Frequency Noise Using the 190-204 Oscilloscope • Acquisition Rate Using the 190-204 Oscilloscope • AC/DC Coupling Using the 190-204 Oscilloscope • Bandwidth and Noisy Waveforms Using the 190-204 Oscilloscope • Mathematics (FFT) Using the 190-204 Oscilloscope • Reference Trace Using the 190-204 Oscilloscope • Meter Mode Using the 190-204 Oscilloscope • Trend Plot Meter Using the 190-204 Oscilloscope • ZOOM Button Using the 190-204 Oscilloscope • CURSOR Button Using the 190-204 Oscilloscope • Record Waveforms in Deep Memory Using the 190-204 Oscilloscope • Scope Record in Single Sweep Mode Using the 190-204 Oscilloscope • REPLAY Button Using the 190-204 Oscilloscope • Trigger Level Using the 190-204 Oscilloscope • Saving and Recalling Using the 190-204 Oscilloscope • FlukeView Scope Software Demonstration Conclusion • Questions?