Professor Sampler’s Notes: Analog vs Digital

Topics Covered:

  • Why we can’t have our cake and eat it too

As to marriage or celibacy, let a man take which course he will, he will be sure to repent – Socrates

If you’re looking for a shootout you’ve come to the right place.

Here’s the challenge: A kid hits a piano note, and a violinist sitting on another continent plays back the same note on her violin. The entire system must be automated once installed. Here’s a highly simplified comparison of this workflow – one in analog and the other in digital:
The Piano Note Shootout
What are we supposed to look for? For one, try to find the relevance of the boxes highlighted in green. Understanding this will tell you why both systems are still used today.

The greatest advantage of the analog signal is its ‘resonance’ with nature. It understands nature, like our bodies do without our minds having anything to do with it. This explains why some high-end audio systems still use analog exclusively, because their supporters claim that the sounds produced are more real and pleasurable than those produced by digital systems. The greatest disadvantage is that analog systems change with every iteration. There’s always a loss – what we get at the end is an approximation of the original intent at best.

The greatest advantage of the digital system is the fact that it can keep the information in the signal over the longest possible distance without loss. This ‘distance’ can be measured in terms of space (kilometers or light years), or time (hours or years). The greatest disadvantage of digital systems is that they have to sample, and depending on the ‘translator’ the intentions of the original analog signal might be distorted, destroying it forever. Imagine what havoc crappy translators can do in negotiations between two rival kings who don’t speak the same language. The ADC and DAC are the weakest links in the digital chain.

Unfortunately, we can’t have our cake and eat it too. This is the crux of the matter. It’s really a choice between the devil and the sea, and choices in the real world are governed by a healthy dose of subjectivity among all the math, standards and technology. It’s like one side is playing soccer while the other is playing rugby. If you stay to watch, you’ll go crazy. So please don’t be so hard on the referee (the engineer).

In a battle between a tiger and an alligator, which will win? The tiger will stand a better chance on land, and the alligator will be the likely favorite near a water body. The question is: what is your preferred battleground?

Let’s get back to our shootout. This example explains one key feature of digital systems very well. In order to construct a word, all you need are pulses with values of one or zero – either there’s a voltage, or not. The system doesn’t have to worry about varying voltages, unwanted frequencies creeping in or out, or noise.

To visualize this consider our primitive cave dweller’s effort at drawing an apple. If all he had was a way to outline the image of an apple, we might mistake it for another fruit, or organ or planet. How simple if he spoke English and had just written ‘Apple’! He could even be creative about it and use serif fonts, calligraphy or graphic design with all sorts of colors. He wouldn’t even have to worry about spelling as long as there was a dictionary he could refer to for error checking.

How noise is handled in encoding

Sometimes it is difficult to keep a handle on electrical signals. Usually they have a life of their own. So instead of relying on their idiosyncrasies we just treat all of them the same (All of you guys look the same!). If we see the enemy in uniform, we fire, otherwise we wait. A lot of guesswork is taken out of the equation.

As far as technological trends are concerned, the thought process is in this fashion:
1. Since analog systems are not perfect, why not use digital systems and worry about improving the quality of ADCs/DACs instead?
2. Digital systems can preserve the signal more precisely, so each copy made will match another copy perfectly (at least in theory).
3. Most consumers don’t have fine-tuned senses to distinguish the subtle differences between the effects of analog signals and digital, so why not digital?

Whether or not this thought process will continue in the future will depend on some bright mind(s) who might bring back the glory days of analog systems, or invent a totally new way to transmit signals. Until then we are stuck with what we have.


  • There is no absolute winner. Period.

Links for further study:

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