BACK TO BASICS: Frequencies

There are so many different radio transmissions it’s hard to understand why they don’t interfere with each other. The key is that all these different signals each exist at a different frequency.

It’s kind of like this: You can take a yellow light, and shine it against the wall and the wall will look yellow. You can take a blue light and shine it across the path of the yellow light and the wall will still look yellow. The blue light is at a different frequency so it doesn’t interfere with the yellow light. Even if they are both shining at the same spot, you could use a filter to take out the blue light and you would still have yellow light. Pretty trippy, right?

Signals that carry TV, cell phones, radio and satellite all travel at really different frequencies. Satellite signals especially travels at a super-high frequency so it is more immune to loss through the atmosphere. Frequency is measured in thousands of cycles per second/kilohertz (kHz), millions of cycles per second/megahertz (MHz) or billions of cycles per second (GHz). An AM radio signal might be 1070 kHz, while a TV signal is more around 600MHz, and a satellite signal is about 15GHz. They’re quite different.

Radio and TV signals that come from towers on the ground use either AM or FM, meaning that the wave either gets stronger and weaker (AM) or faster and slower (FM) as it represents different information. Satellite signals use much more complex digital forms of storage that are harder to explain.