PCM

Pulse Code modulation, or PCM, is a way of digitally representing a signal that is analog in nature. While that may seem simple enough, PCM is far from simple. It is used in a number of applications from phones to computers to, in some cases, CDs. However, before you can fully understand PCM tuning, PCM programming or reprogramming, or even PCM audio on its most basic level, you need to understand exactly what PCM is, what its limitations are, and where it comes from.

So What IS PCM Exactly?

As was mentioned before, PCM stands for Pulse Code Modulation. What it does is take normal sound and convert it into digital form. This is what allows you to hear certain music on your computer, certain signals on your phone, and even where the sound comes from on certain forms of DVDs and CDs (though many do not use true PCM, they do often use a form of it). So as you can see, it is a valuable technology and programming format in this, the digital age.

What Are PCM’s Limiatation?

PCM does have its share of limitation as does any form of technology or programming. With PCM, the limitations are basically in two categories.

For one, there is what is called the quantization error. You see, by going from an analog to a digital signal, there is going to be some error in conversion since there is a definite difference in the two signals. When the program converts from analog to digital, the difference in accuracy is called the quantization error. In the best of circumstances, this value is low.

Another problem is aliasing. Analog signals are continuous, which means the digital versions must take samples, albeit frequent ones, in order to reproduce the sound to your ear. The problem is that technically two different sounds in analog could produce similar sampled sounds. This disconnect is called aliasing.

Basically, these two errors can account for much of PCM’s limitations. Even the Microsoft PCM format 1 must contend with such limitations since they are based in the very nature of analog and digital sounds.

Where Did PCM Come From

PCM actually has a long history rooted in the development of the telegraph. Through the years, engineers and scientists played with the idea of taking analog sound and converting it into more transferable digital sound. However, the credit for true PCM is usually given to Paul Rainey of France. His invention was eventually used by the allies in WWII before getting civilian use in the 50’s.