While preparing for a presentation on wireless basics recently, I came across a couple interesting ways of describing channels in a practical way.

Wireless channels are distinct ranges of frequencies that operate in a target frequency band. In the unlicensed 2.4 GHz band, there are 14 separate channels to choose from, but typically we know to only use channels 1, 6, and 11, since they are considered non-overlapping.

But what does this even mean to a human?

Since wireless channels are just different frequencies, you can describe them in the same way you describe anything else that works at different frequencies.

(For comparison with each of these techniques below, the common Wi-Fi frequency bands are 2.4 GHz (giga-Herz, or 1-billion Herz), and 5 GHz.)

Audio

Sound waves are nothing but different frequencies – high and low pitches are just high and low frequency sounds.

Human hearing is generally between 20 Hz and 20 kHz (kilo-Hertz, or 1,000 Hertz).

For a very practical demonstration, pull up a tone generator on two separate computers, or two browser tabs. Set one tone to 440 Hz and the other to 640 Hz.

Now start and stop one of them to create an encoded signal, like Morse code.

You can easily pick out the signals of one frequency, even when the other is turned on, and vice versa.

Experiment by seeing how close together you can get the two frequencies before you can’t tell the difference anymore. This would be equivalent to having two channels too close together (like channels 1 and 2). The signals interfere with each other. There needs to be a minimum space between the two signals before you can properly distinguish them.

Color

Color is just different frequencies in the visible spectrum. Channel differences can be observed in the same way that Blue is different than Red – they are both forms of light, but you can tell the difference just by observing them.

Visible light frequencies run in the 430 – 750 THz (tera-Hertz, or 1-trillion Hertz) range.

If two signals are being sent at the same time with different “colors”, you can see them as whatever color represents those two colors mixed. When both the Red and Blue signals are being sent at the same time, you’ll see pulses of Red, Blue, and sometimes Purple. A computer would be able to detect the pulses and separate out the two signals.

You can also see how having two colors too close together might interfere with each other, like Red and Orange might not have a mix color that can be properly distinguished. This would be equivalent to having two channels too close together.