Basic signal types

Basic signal types#

In this section, we will briefly introduce a few basic signal types that are commonly used in conceptual ocean acoustics discussions.

Sine Wave#

A sine wave is a signal with constant amplitude and frequency that can be described by:

\(y(t) = A \sin(2 \pi f t + \mathcal{\phi)}\),

where:

  • \(A\) - peak of the deviation of the function from zero

  • \(f\) - the number of oscillations occurring within a second

  • \(\phi\) - where in the cycle the wave is at zero (in radians)

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Chirp#

Another example of a signal is a chirp, or a signal with an increasing or decreasing frequency.

We will generate example with linearly increasing frequency from 1Hz to 10Hz.

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Often when we want to transmit a chirp, we would taper the beginning and end of the signal, so that signal plays nicely with the physical turing on and off the transducer.

We can achieve this by “windowing” a signal. The same technique is also often used to “cut out” part of a long signal.

There are many different window functions (see here for a list in scipy). In the example below, we generate a Tukey window and use it to taper a chirp.

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Impulse#

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