can be used for a large number of vehicle tests.
The waveforms used
as examples in this book
were ‘captured’ using this device. This type of test
equipment is highly recommended.
3.2.2 Waveforms
You will find the words ‘waveform’, ‘pattern’ and
‘trace’ are used in books and workshop manuals
but they mean the same thing. When you look at
a waveform on a screen
you must remember that
the height of the scale represents voltage and the
width represents time. Both of these axes can
have their scales changed.
They are called axes
because the ‘scope’ is drawing a graph of the volt-
age at the test points over a period of time. The
time scale can vary from a few s to several
seconds. The voltage
scale can vary from a few mV
to several kV. For most test measurements only
two connections are needed just like a voltmeter.
The time scale will operate at intervals pre-set by
the user. It is also possible to connect a ‘trigger’
wire so that, for example,
the time scale starts
moving across the screen each time the ignition
coil fires. This keeps the display in time with the
speed of the engine.
When you use a full engine
analyser, all the necessary connections are made
as listed in the table in Section 3.4.1. A hand-held
scope has to be connected for each waveform as
required.
All the waveforms
shown in various parts of
this book are from a correctly operating vehicle.
The skill you will learn by practice is to note
when your own measurements vary from those
shown here.
3.2.3 PC based two-channel
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