What is AM?

AM, which is an acronym that is commonly used in the term “AM radio broadcasting”, stands for “Amplitude modulation”. Basically, it is just a form of broadcasting that makes use of amplitude modulation to broadcast a signal. This is the type of signal picked up by AM radio in your stereo.

The very first, experimental broadcast to take place on AM radio took place in 1906 on Christmas Eve. This experiment was conducted by a man named Reginald Fessenden. It was KCBS, however, that gets the credit for being the first ever real AM radio station.

This station is actually a direct descendent of KQW, which was founded by a man known as Charles “Doc” Herrold, who was a radio experimenter. In this respect, KCBS is actually the first and oldest broadcasting station.

AM radio transmission and reception is pretty straightforward. It is actually much simpler than an AM FM radio. With AM radio, all you need is a receiver that will pick up amplitude variations in radio waves at a specific frequency.

The radio will then amplify the changes in the signal, which is what drives the headphones or loudspeaker attached to the receiver. The very early AM radios used Crystal diode detectors, and thus, did not directly need amplification.

One thing that is interesting about AM radio signals is that they travel much further during the night than during the day. This is due to changes in the ionosphere that cause the AM radio waves to travel by “sky wave” during the night hours.

For this reason, some AM stations are required to cease broadcasts at night. These stations, which only broadcast during the day, are called “daytimers”. Some people consider AM radio a fascinating hobby, because it allows them to pick up broadcasts from many miles away.