So I was thinking the other day about cordless phones, wireless networks, cell phones, and interference. It occurred to me that there is only one way that I know of for information to travel through air, and that is waves (radio waves, to be precise). In addition to that, we have the cell phone companies selling us digital service and the cordless phones at the store with “Digital DECT” technology being advertised. And something hit me. How is it really possible that these things are digital over the air? Especially when non-digital signals and obstacles can create unwanted interference? I went to good ol’ Google for my answers and found a partial answer from Compukiss.com here: http://www.compukiss.com/basics/digital-vs-analog-2.html. Basically, what they’re saying is digital information is discontinuous – like short bursts. And analog information is a continuous stream.
So as an explanation, think about a radio station’s signal. You tune your radio to a certain frequency and your radio plays music that it receives from the signal that the station’s tower emits. What happens with a radio station’s signal is that they use a radio wave (which is analog) to carry a second wave (a sound wave) of information that gets decoded by the electronicss in your radio (technically, a receiver). With analog radio, this is a purely analog transmission.
With all the other electronics that claim to be digital, it’s very similar. There’s a bit of explanation at the How Stuff Works site here: http://www.howstuffworks.com/radio.htm. Let’s say you have a cordless phone in your house. You speak into the phone and the electronics in the phone turn the sound wave into digital bits that get transmitted to the base that’s attached to the phone cable that leads back to the phone company. The digital bits are the part of the process that is digital. So, technically the manufacturers and sales clerks are not lying when they call a product digital. What they fail to tell you, though, is that there hasn’t been a digitization of radio wave technology. Your digital bits are being carried from your handset to your base on a radio wave – the same analog technology that lets you listen to your favorite radio station. So, even though the information you are sending is digital, the vehicle it travels on is the same old analog stuff we’ve been using for some time now.
Call me naive, but I thought (somehow) that we had moved to some kind of new wireless technology that operated on some digital technology completely beyond the scope of my understanding. Wow, was I wrong. It’s really all still analog.
I wonder if a digital wireless signal is possible. It may be, but I think that it might require a sophisticated understanding of quantum physics, which I don’t have. I only have a basic understanding of high school physics that I am working with here. I bet that it would be pretty impossible, since digital data still needs a meduium to carry it, whether the medium is a radio wave, CATV cable, optical cable, or something else. These media all seem to fit into the analog category, so we’ll see what some awesome quantum physicist can bring to us, I guess.