Specifications

7
Signals
With regard to the oscilloscope, the term signal means a voltage that may vary in value as a function of
time. One distinction is whether the signal is periodic or not. Periodic means that the signal repeatedly
takes on the same set of values over various intervals. The sine wave is one example of a periodic
waveform. Let's look at some of its features:
Figure 2
Frequency measurements
Figure 2 shows two periods of a sine wave. A period is the set of points consisting of the basic shape
of the waveform. The sine wave takes on various values between point a (t = 0) and point b (t = 6.2).
The waveform then repeats this set of values from point b to point c. The time from point a to point b is
called the period of the waveform. In the figure, you can see that the period is 6.2 ms.
The frequency of a signal is the reciprocal of the period:
frequency =
1
period
Frequency is measured in Hz (hertz) and is dimensionally equal to reciprocal seconds (s
-1
). In this
document, we'll use the symbol f for frequency. Another measure of frequency is angular frequency
(also called radian frequency), which is often denoted by  and is equal to 2. It is used because
sine waves and their analysis lead to trigonometric formulas, and are most simply and easily expressed
in radian measurement.
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