Analog and digital data

I thought that I would talk about digital media -- CDs, DVDs, Blu-Ray, and so forth. But then I realized that I really needed to first talk about what digital media are -- and that, in turn, means that it is important to talk about analog.

Analog data are a reflection of events that occur on a continual basis. Such things include time, temperature, sound, moving images, water flowing, and so forth. An analog watch is known by its "face" -- where the "hands" are located to allow a person to interpret the data (information).

It would be completely possible for a watch to have a single hand. All the information is present in the hour hand. However, it is difficult to "read" (interpret) the value with a single hand and, therefore, analog watches and clocks normally have a minute hand and may even have a second hand.

In my old university, they had an analog computer. Set up correctly, it would be able to be used to calculate an exact value for Pi. But this brings up further the problems with analog data -- being able to actually make use of the data in a precise manner.An analog thermometer can give a precise value but can a person really read it that clearly? Is it saying 98.6 or saying 98.53?

Digital data can only create approximations of continual information. There are a lot of non-continual data in the world -- particularly in the area of finances. However, when it comes to continual data, you are involved with sampling rates and precision. The sampling rate is how often you "mark down" the information. You take a sample of sound at 1 hour, 20 minutes, 15 seconds, and 180 milliseconds. You then take a sample of the sound every 20 milliseconds -- but, whatever interval you choose, you are also choosing to ignore the data that exists when you are not taking a sample. You will never really know what happened within that 20 millisecond gap. You can guess what it might be -- that is called interpolation -- but you cannot know.

The second part of digital data is precision. For money (or other non-continual data), the precision is self-defined by what exists (although other units may exist for formulas -- like taxes). For continual data, the precision is a choice. Do you record 98.5, 98.54, 98.536, 98.5359, or what? Once again, you lose data/information and your choice CAN make a difference if the data are used in a repetitive fashion (such as calculating trajectories for a space ship).

So, analog data are accurate but very difficult to interpret precisely. Digital data are an approximation but have ease of interpretation as a built-in aspect of the choices that are made.

And this leads into the next blog "What makes Blu-Ray (TM) Blue?"