Its already begun. Digital is here. “You’re on analog? lame.” A lot of banter has been going around about digital this and digital that as of late. You’ve heard the Circuit City ads, always going on about how digital is so much better than analog was. I also get a sneaky feeling that 60% of the people I know saying these things have no idea what they’re saying, and just like jumping on bandwagons whenever the chance arises. Luckily, I’m here to clear up the confusion :-D. As you may know, analog, the conventional data transmission standard for decades is soon loosing one of its last strongholds in the U.S.A. Coming next year, analog television broadcasts will cease, leaving Americans like myself with the option of digital TV or no TV. Of course, digital is a good thing for reasons I will explain later in the article. Frankly, in my opinion, the difference in quality is not worth the hype digital information transfer has received, but it is indeed important. What exactly makes digital better than analog? First, we’ll talk about exactly what these two terms mean.
Analog was of course, the first way people transmitted data. Analog information is sent using an electromagnetic radiation of some sort, and has a continuous or infinite level of precision. You can tune the parameters to be as precise as you want to be. Digital is discrete. There’s no continuum of data you have to process, its just a Morse code like stream of “on” and “off” signals that are processed to create a picture, or sound, or whatever data you are transmitting.
Wait a minute. Analog has the potential to have infinite precision? How is something with potentially an infinite level of precision worse than something with precisely 2 levels of precision? In a perfect world, we could use analog to much greater effect than digital. Three real world considerations are the explanations for why digital results in better data transmission.
Limits of Engineering An infinite spectruum takes infinitely precise tools to transmit and receive. Of course, such tools do not exist. Circuit elements are never exactly what their label says, they vary by a few percent. You can never build a perfect system. You can get very close, but no where near the infinitely precise level you would need to take advantage of all that analog would offer. Luckily for us though, infinite precision is overkill. The human body cannot process an infinite spectruum of quality, there is a point at which you cannot tell the difference the more and the less clear picture. Digital, even in its discreteness, can get to that level where you cannot tell the difference. The limits of what we as humans can process is partly the reason why digital can match analog in apparent quality.
Digital is Distortion Proof (kinda…) Alright then, if analog has the capability of transmitting an awesome picture, then why are even bothering switching? The answer is in transmission. Anything that is transmitted is distorted in some way. Analog transmisision over wires is distorted by the resistivity of the wire, among other factors. Over the air transmisisons are distorted by lots of things, like stray electronic signals. Don’t get me wrong here, digital signals are also distorted. The critical factor here is that digital distortion can be reversed where analog distortion cannot be reversed. This is best shown with a picture.
The analog transmission is on the left side, analog on the left. Red line is the distorted signal you recieve and the black line is the original signal. As you can see on the analog side, that bump of information is lost by distortion. How can we get it back though? We can’t. You can have no idea of how to restore the signal to pristine condition without seeing the original signal. There could be a bump or there could not be, we have no way of reconstructing this. Look at the digital side though. Yeah, it got distorted, but you can sure see where the “on” signal and the “off” signal is. This can easiy be recovered with processing circuits. This data distortion recovery is probably the biggest reason why digital information transmission is taking over.
Cost of Engineering Digital engineering is in many aspects, much cheaper and easier to do than analog. You’re not going to hear electronics producers trumpeting this, but its true. Analog engineering requires lots of differential equations, and careful engineering. It also takes expensive, high quality parts to make a high quality product. Digital engineering requires little to no application of differential equations on the whole, and a high quality set can be made with lots of cheap low quality digital parts. Analog is simply more expensive to get right.
So now you have enough ammunition to fire back at those cocky electronics salesmen! 😀 My next article will be on the basics of digital encoding, so ‘stay tuned’ for that!