![]() ![]() Using special circuits and filters, single sideband transmissions can consist of either the lower sideband (LSB) or the upper sideband (USB). Soon the experimenters were able to filter out the carrier and either of the sidebands to yield what we now know and use as Single Sideband! So we are using a single side aning one side band. ![]() DSB was typically used in the earlier experiments because it was much easier to filter out just the carrier than to filter out the carrier and one of the sidebands. This is known as double sideband (DSB) without the carrier. Many methods were experimented with and ham radio operators often used both sidebands without the carrier using special circuits in the transmitter to eliminate the carrier wave while still leaving the modulation to be transmitted. Although AM signals were transmitted almost exclusively for decades, it was discovered with experimentation that the AM signal could be modified yielding much better results! They contain the "information or audio" intended for the receive station. The audio sidebands that form an AM broadcast signal are quite important. These two modulating (audio) sidebands are located on either side of the carrier wave, one just above it and the other just below. This is the carrier you are hearing being detected by your receiver. When the radio transmitter you are tuned to is not transmitting any sound, you can still hear from the speaker and see on your S meter that a signal is present due to the background noise being quieter than either side of that frequency. They are a mirror image of each other, identical in every way.Īny audio that you hear on an AM receiver is from the two sidebands. Due to the nature of the way AM is produced in the transmitter, two identical modulating signals are attached to the carrier wave, these are called the sidebands. In an AM modulated radio signal, the carrier, is continuously transmitted. The carrier wave is used to "carry" the audio information to the AM receiver where it is detected and transformed back to an audio signal that we can hear representing the original information (voice) that was spoken into the microphone. When you are in the AM mode, your voice modulates, (is superimposed), on a carrier wave at a certain frequency in your transmitter and is transmitted over the air waves. You may also have used single sideband on other occasions also, but since you are reading this, you want to know more. You have used FM modulation on the 2 meter ham band and most likely used AM modulation when you were a kid using toy walkie talkies. There are two types of modulation that most people are familiar with, AM (amplitude modulation), and FM, (frequency modulation), for which the AM and FM broadcast bands were named. To modulate a radio wave is to add information to it that can be received on a receiver for some useful purpose. The method by which audio, (information), is impressed on a radio signal is called modulation. It is a very efficient method of superimposing your voice or other information on a radio wave and the transmission of that radio wave. Single sideband is more properly called a "mode" like AM or FM. ![]() It is not a rock group! It is not.what you may have thought! Single sideband is not a band! It is not a frequency! It is not a portion of a band! This article is tailored and written for the new ham.Īrticle written and compiled by N4UJW and updated 01-2014 First we must understand what single side band is not! ![]()
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