Electromagnetism In Radios/Walkie Talkies

Myalee Smith

Hand radios otherwise known as Walkie-talkies first came about during the second world war.  It was so big that it had to be carried on a backpack and was called a packset but later became known as a walkie-talkie.  This was made during the 1940s but the first hand held one that did not require a whole back pack to carry was made in 1941 and was the AM SCR-536 transceiver.  It used vacuum tubes and high voltage dry cell batteries.  The hand held transceiver was called the Handie-Talkie since it was hand held and didn't require a whole backpack to walk around with.  To be a transceiver means that it can receive radio waves and send radio waves.  Walkie-talkies now a days use a half-duplex channel meaning only one radio can work one a channel at a time.  The channel can receive multiple signals at once but only one will come through.   So one radio signal can interrupt the other and be the only one heard.  Walkie talkies also have a PTT system, which means Push to talk system, and is most commonly found in walkie talkies.  When you speak into a walkie talkie your voice is converted into radio waves on the electromagnetic spectrum which means they travel at the speed of light.  Which is 186,000 miles per second.  

In the early days of radios the transmitters were called spark coils which continuously treamed high voltages of 20,000 volts or higher.  These transmitters could travel farther but are no longer in use because of the immense sparks they create and how it affects a lot of the electromagnetic spectrum.  Like many many things around us radios use continuous sine waves to spread information.  Such as the radio you listen to in your car on the way to work, or the TV you watch when you get home, use sine waves.  But they use different frequency of sine waves so that they don't interfere with each other. Walkie talkies use millions of different frequencies that can be measured with Hertz or cycles per second.  There are also many different frequency bands radios can be on.  There are even set frequencies for different sets of people to use such as the FRS, or Family Radio Service and the GMRS or General Mobile Radio Service.  These two common radio channels often operate on the 460Mega Hertz range.  There is also a Business band that operates between 450Mhz and 470Mhz.  But since these bands can infinite amount of transmitions there is often interference on public channels.

https://electronics.howstuffworks.com/walkie-talkies2.htm

https://en.wikipedia.org/wiki/Walkie-talkie?scrlybrkr=88069be5