For a beginner, it may cause confusion that when we want to make long distance (DX) contacts we utilise SSB mode. What is the reasoning behind this choice of mode? And why does it nominally seem to yield a further range than AM/FM?
First we must briefly review each mode and explain how they modulate the voice.
AM
AM or Amplitude modulation is one of the most well known modes on 11 meters.
Amplitude modulation uses the amplitude (Volume) of the incoming voice to modulate the signal. It nominally has 8 khz of bandwidth for the voice.
FM
FM, Frequency Modulation is another voice mode that is widely utilised on 11 meters, it uses the frequency (Pitch) of the voice to modulate the waveform. It has a larger bandwidth than both SSB and AM at 10 khz. FM CB radio is described as having the highest audio quality due to this increased bandwidth, however this comes as a compromise between range as we will describe later in the article.
SSB
The article explains the differences between AM, FM, and SSB modes and how they modulate the voice. It also discusses why SSB mode is often used for long-distance (DX) contacts and why it provides a further range than AM/FM.
Congratulations Daniella for explaining the technical concepts in a clear and concise manner. This article is a great resource for beginners who are looking to understand the basics of amateur radio communication.