GxT Ferret 92 Color Labscope - Manual (Page 16)

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LabScope Basics
Application:
A LabScope, or Digital Storage Oscilloscope (DSO), performs only one basic function. It displays voltage over a
period of time. Think of your LabScope as a voltmeter, connected to a VCR, which in turn is connected to a television.
Like a voltmeter, it receives voltage inputs. Like a VCR, it records and stores the inputs. Like a Television, it displays
the inputs. Because it records and stores inputs before displaying them, electrical events that occur in less than a
thousandth of a second can be displayed in detail.
Although the LabScope only displays voltage, it can be used in conjunction with various accessories and a good
working knowledge of electricity to measure amperage, dynamic resistance, frequency, temperature, pressure and
a variety of other things.
Terminology:
If you’ve never used a LabScope, there are a few new terms you’ll need to become familiar with. Most will be
covered in more detail in later chapters.
1. ................................................................................... Amplitude: vertical height (voltage amplitude)
2. .................................................................................................................... Capture: displayed input
3. ................. Coupling: setting that allows the constant component of a signal to be blocked, or not
4. .................................................... Current ramping: the process of capturing amperage waveforms
5. ................................................. Cursors: movable lines used to measure time or voltage on screen
6. ........................................................................................Division: segment of either height or width
7. ..........................................................................................Duration: Horizontal width (time duration)
8. ........................................................................................... Ground Line: horizontal line at zero volts
9. ........................................................................................................ KV: kilovolt (one thousand volts)
10. ................................................................................ mS: millisecond (one thousandth of a second)
11. ........................................................................................... mV: millivolt (one thousandth of a volt)
12. .............................................................................Signature: defi ning characteristic of a waveform
13. ...................................................................................................Slope: direction of voltage change
14. ............................................................... Time base: length of time set for display (Pattern sweep)
15. ...................................................................................................... Trace: image displayed (Pattern)
16. .............................................. Trigger: setting that determines when scope begins to draw a trace
17. ................................................................................................Trigger Level: voltage level of trigger
18. ................................................................................... uS: microsecond (one millionth of a second)
19. ...................................................... Voltage Scale: range of voltage set for display (Voltage Range)
20. .............................................................................................Wave form: trace of a particular signal
Settings:
Settings are the controls that allow us to tell the scope what we want to see on the display and how we want to see
it. Because we will be dealing with signals that vary in voltage range and occur over a variety of time frames, it will
be necessary to adjust Voltage Scale and Time Base to properly view different signals. You may also need to tell
the scope when to begin drawing the trace. This is called Triggering. With certain types of Triggers, you will need
to set a Trigger level (voltage level for the trigger). You must also tell the scope if you want to block the constant
component of a signal or not. This is called Coupling.
Voltage Scale:
Component operating range needs to be considered when setting Voltage Scale. To determine the voltage range
a component operates within we need to look at a few things:
Supply Voltage: If we’re looking an average actuator, supply voltage is usually very close to system voltage, or
around 14 volts. If we’re looking at an average sensor on most systems, supply voltage is the same as VREF,
generally about 5 volts.
Inductive Kick: Ignition coils, fuel injectors, solenoids and other components with wound coils produce a magnetic
fi eld around the windings when powered up. When the circuit is opened and the fi eld collapses, a voltage is induced.
We call this inductive kick, or voltage spike. Induced voltage can be several times higher than supply voltage.