What is an analog signal?
To understand what analog signals are let’s take the example of your friend waving at you when you two leave the school. As she moves her hand from left to right, it passes through each and every point possible between the two end positions. Since waving at you is conveying the information of parting ways, it is a signal; since it touches all the points or values present between the extreme left and extreme right position, it is a continuous signal or an analog signal.
An analog signal, therefore, is a signal that represents all of the possible values in a given range as it varies with respect to time; it is analogous to the time-varying quantity it represents.
Visualizing Analog Signals
It is easier to visualize an analog signal on a graph. A graph is a mathematical diagram which depicts the relationship between two quantities. It consists of two axes: the x-axis and the y-axis. Each axis represents one out of the two quantities. When being used for representing analog signals, the x-axis represents time and the y-axis represents the signal. For an analog signal, the graph is always smooth, and continuous. Let’s perform a small activity to see what it looks like:
What you need:
- Two male-to-female jumper wires, and
- Our dear friend, evive
What you must do:
- Take one of the male-to-female jumper wires and connect one end to the A9 pin; the A9 pin is on the very top, next to the 5V and GND pins of evive. This pin is internally connected to the potentiometer knob 1 that is right next to the tiny black screen, known as the TFT screen. We’ll learn about potentiometers in the next topic. At the base of evive, you’ll see three pins with GRAPH written on top of them. Take the free end of the wire and connect it to the leftmost GRAPH pin.
- Next, take the second wire and connect one end to one of the GND pins in the top left corner. Now, take the free end and connect it to the GRAPH pin in the middle.
- Once you’re done, switch ON your evive. When you do so, you’ll see a menu on the TFT screen.
- From the menu select Mini Oscilloscope by pressing the navigation switch to the right. As soon as you select the oscilloscope.
Below is the complete circuit:
The curve that represents the shape of the signal is called a waveform. As you vary the voltage by rotating the potentiometer knob, you’ll notice that the waveform changes. When you rotate the knob clockwise, the size will increase; when you rotate it anticlockwise, the size will decrease.
Other examples of analog signals include your heartbeat, your voice, and the songs that you listen to or are made to listen to.