Specifications

4
Electronic Signals (continued)
Waveforms
Triangular/sawtooth waves
In a triangular wave, the voltage
varies linearly with time. The
edges are called ramps because
the waveform is either ramping
up or ramping down to certain
voltages. A sawtooth wave looks
similar in that either the front
or back edge has a linear voltage
response with time. However,
the opposite edge has an almost
immediate drop.
Pulses
A pulse is a sudden single
disturbance in an otherwise
constant voltage. Imagine flipping
the switch to turn the lights on in
a room and then quickly turning
them off. A series of pulses is
called a pulse train. To continue
our analogy, this would be like
quickly turning the lights on and
off over and over again.
Pulses are the common waveform
of glitches or errors in your
signal. A pulse might also be the
waveform if the signal is carrying
a single piece of information.
Complex waves
Waves can also be mixtures of the
above waveforms. They do not
necessarily need to be periodic
and can take on very complex
waveforms.
Analog versus digital signals
Analog signals are able to take on
any value within some range. It is
useful to think of an analog clock.
The clock hands spin around the
clock face every twelve hours.
During this time, the clock
hands move continuously. There
are no jumps or discreteness
in the reading. Now, compare
this to a digital clock. A digital
clock simply tells you the hour
and the minute. It is, therefore,
discretized into minute intervals.
One second it might be 11:54 and
then it jumps to 11:55 suddenly.
Digital signals are likewise
discrete and quantized. Typically,
discrete signals have two possible
values (high or low, 1 or 0, etc.).
The signals, therefore, jump back
and forth between these two
possibilities.
Figure 5. A triangular wave
Figure 6. A sawtooth wave
Figure 7. A pulse
Oscilloscope Fundamentals