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?