Digital Overview

What is Digital communications?

We all grew up in the analog communications world, choosing between Amplitude Modulation (AM), Frequency Modulation (FM), or if you were a Ham, Single Side Band (SSB) modulation.  All three were similar techniques to send primarily voice or music.  AM would adjust the amplitude (strength) of the transmitted carrier at the voice frequency.  FM would slightly vary the frequency of the transmitted carrier at the voice frequency.  SSB is a special case of AM the uses half the bandwidth, poor for audio quality but good for DX.

Digital takes a different approach that uses pulses of energy, all the grandchild of Morse Code.  It is easier to detect if a carrier is transmitting (a digital “1”) or (a digital “0”) than detecting subtle changes in amplitude or frequency.  Morse Code is slow, typically less than 30 words per minute, but served us well since Marconi’s first transmission in 1897 because that was the speed that humans can send or understand.  Modern microprocessors changed everything.

Today, the processing power in even the simplest of ham radios can turn pulses on and off at blazing speeds, and they can control the personality of individual pulses, pulse spacing, groups of pulses, and more.  This makes it possible to send not just voice or music, but expanded data options such as text, images, location, internet voice and more, all at speeds that Marconi couldn’t even imagine.  The engineering and radio guru’s are constantly inventing and tweaking new ways of sending digital information based on some fundamental techniques.

Many variations of these techniques are implemented under many names, each with their own merits. Some examples are:

If that wasn't enough, different manufacturers implement digital modulation schemes under their company terminology such as DMR (Motorola & others), D-Star (Icom & Kenwood) or System Fusion (Yaesu).  

. . . But do we care?

Pros and Cons of Analog Radios (VHF/UHF)



Pros and Cons of Digital Radios (VHF/UHF)