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

X axis, time (Seconds)

Y a

xis,

Am

pli

tud

e (V

olt

s, d

B)

Z axi

s, F

requen

cy (H

ertz

)

110.56 Vac

Vo

lts

time

• A multimeter precisely measures a signals amplitude

• An osciloscope displays a signal amplitude change over time

• A spectrum analyzer displays a signal power level (amplitude) with respect to frequency

dB

Frequency

What is a multimeter?• A Multimeter accurately displays discreet Volts, Ohms and Amp measurements.

• 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

Time in Seconds

Am

plitu

de in

Vol

ts

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

“A picture is worth a thousand words!”

Am

plitu

de in

Vol

tsTime in Seconds

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

Input Coupling• AC or DC

Amplitude Control• Attenuation• Amplificatio

n

Channel Isolation• Up to 1000

Volt isolation

• Available on some scopes

A to D Conversion• Real time• Up to 2.5

GSa/s

System Control• Sample Storage• Measure functions• Graphics

processing• User interface

Ch A2.5 GSa/s

A/D

Lf

Hf

Optional Ch Isolation

Micro Processor

Memory

Triggering• Edge• Edge

Delay• Pulse

Width• N-Cycle

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

Gnd Ref

Applied Input Resultant Output

DC Coupling

AC Coupling

AC & DC Signal Components

AC Signal Component, DC is blocked by capacitor

Gnd Ref

Gnd Ref

Display Amplitude Control• Controls the vertical span of the displayed signal, adjusted in volts per

vertical display division– mV increases sensitivity– V decreases sensitivity

mV

V

Gnd Ref

Gnd Ref

Gnd Ref

Vertical Sensitivity (V/Div)Amplitude display range

Pressing mV increases vertical sensitivity

Pressing V deceases vertical sensitivity

Analog to Digital Conversion

1 2 3 4 5 6 . . . . . . . 1000

Horizontal Time base (s/Div)Sampling clock interval timeHorizontal resolution

mS/Div

• 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

S/Div

A to D Conversion

Storage Memory

Gnd RefGnd Ref

Sample Rate & Memory• 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)

Mem

ory

Dep

th

time

Cost

Sam

ple

Rat

e

Time base ns Min

S

gS

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

Over Sampling Glitch Detect• The Min & Max samples

displayed in each column

Displayed Max Sample

Displayed Min Sample

Display Pixels

Oscilloscope Bandwidth

Frequency 1 Frequency 2 Frequency 3

• 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

Perceived Volume

Triggering• Triggering, synchronizes the waveform display process every time the

waveform is refreshed or displayed.

1

2

3

4

Composite image of “Un-Triggered” scope

T

Triggered, resulting in stable display

Acquisition cycles

Triggering Techniques• Oscilloscopes use several techniques to

trigger on unknown signals– 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

V level

V level

time

V/Div

Time/Div

Trigger

Oscilloscope Isolation• 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

• 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.

Isolated adapter DC Out

AC to DC Power Adapter, specially designed to meet CAT II 1000V/ CAT III 600V Safety rating

Ref A Ref B

Channel 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 A Signal Input

CH B Signal Input

CH A Reference Input

CH B Reference Input

CAT II 1000 V/ CAT III 600V Isolation

Common reference tied to earth ground

CH A 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?