Friday, January 8, 2016

More understanding digital

A while back I referenced a couple Hak5 videos that talked about Pulse Code Modulation and Time Division Multiplexing.

It should be obvious by now that I feel we have pretty much reached a stone wall with conventional FM modulation.  Carsons bandwith rule pretty much tells us we will always be limited in the amount of information we can carry using a traditional FM signal.  It's time we amateurs look into and start experimenting with more modern OFDM and QAM modulation.

This is why I feel repeater coordination and the VHF and above band plans need some serious re-thinking. How are we evolving these to accommodate other modulation methods?   If you recall VHF and UHF used to be dominated by AM till Wayne Green came along promoting FM.  Well maybe its time for some change again?

It's 2015, and I feel for the most part the commercial networks are stable, and our role as hams for emergency communications as compared to the past is greatly diminished.   I feel its time to focus on one of our other major basis and purpose pillars, to advance the radio art.

In this day and age its important to understand digital communications.  I have been hoping that since the amateur license classes have been consolidated down to three that a new one would be introduced.  The digital communicator license scheme of sorts.  Hopefully I'll see this in my juncture in the hobby at some point.

Anyway let me introduce you to Claude Shannon.  He founded information theory, which is the basis for all things digital.  He is often called the father of the information age.

Information theory is pretty deep.  I have yet to find a good watered down version of it for entry level hams.  A number of years ago TAPR published a book titled "Wireless Digital Communications: Design and Theory," and this is probably as good as I have found.

John Stephenson, KD6OZH who passed away in 2014 was pioneering modern modulation techniques.  Now we just need to carry the torch on.

PS; When you are done watching the Shannon video and doing your research homework on KD6OZH, you can view this DSP amd Nyquist video.

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