How Radios Work

Have you ever wondered how your radio works?

In the air right now there are many type of waves. Radios take these electromagnetic waves and convert them into sound, They do this by using a receiver and an antenna. The antenna pick up on the waves frequency and sends them to the receiver (tuner, detector & amplifier) which then turns them into the sound that you hear.

http://electronics.howstuffworks.com/radio8.htm

http://en.wikipedia.org/wiki/Radios

Sine & Cosine Applications

Examples of Real Life Sinusoids:

Pendulum:

 Engine (Piston-crankshaft):

Ocean Waves:

Sound Waves:

Plus Many More!+++++++



Real Life Sinusoid Function:

 Middle A: y=asin(880πt)

Frequency: 440 htz y=wπ/2π

http://www.ikmultimedia.com/forum/viewtopic.php?f=28&t=2290
graphsofsineandcosine.weebly.com
http://gem-ini.tumblr.com/post/28123864990
http://sopsinvestigations.com/sops/?p=58
http://www.mathdemos.org/mathdemos/sinusoidapp/sinusoidapp.html

AM vs FM

The first difference between AM and FM is what their abbreviations stand for. AM is amplitude modulation where FM is frequency modulation. Modulation is the act of modifying the carrier frequency in accordance to the information being sent. AM modifies the amplitude of the carrier frequency while FM modifies the  frequency of the carrier.

AM is the older, and easier of the two. An AM radio detects the changes in the carrier frequency’s amplitude before sending it through a speaker. The one main downfall with AM broadcasting is that the signals are easily distorted by bad weather conditions. AM travels a much greater distance than FM, but it was only able to output one audio channel. The greater range of AM waves is why talk radios prefer to use AM broadcasting.

FM is much more complex than AM radios. The greatest benefit of an FM radio is that it has the ability to send out two channels of information at the same time. This allows a radio station to broadcast left and right audio channels for greater stereo sound. FM waves can not be easily affected by weather conditions making them more ideal for listeners. FM broadcasts are mainly used for music as opposed to talk radios. The major downfall of FM radios is that FM signals usually drop off at around 50 miles from the broadcast station.

Sources: http://www.differencebetween.net/technology/the-difference-between-am-and-fm/
http://www.pbs.org/wgbh/aso/tryit/radio/images/fmamcompare.gif

History of Radio

To understand the history of the radio we need to take a look at those who have been given credit for "fathering" the radio and each of their contributions. 

James Clerk Maxwell: He formulated the classical electromagnetic theory.

Heinrich Hertz: First to prove that you could transmit and receive electric waves wirelessly. We recognize Hertz's work today as the fundamental building block of radio and every frequency measurement is named after him (Hertz).

Guglielmo Marconi: Introduced many of the first uses of wireless telegraphy to European navies.

They say his radio apparatus is considered to be the reason that

 over 700 people survived the Titanic disaster in 1912. 

Edwin Armstrong: Creator of the FM radio, invented the regenerative circuit, the amplifying receiver, and a wave transmitter. His inventions allowed us to be able to recieve, convert, and amplify weak, high-frequency electromagnetic waves.
Reginald Fessenden: Developed a way to combine sound and radio carrier waves.

1885: Hertz proved electricity can be transmitted in electromagnetic waves.

1891: Radios began to appear on ships.

1892-1893: Nikola Tesla transmitted electromagnetic energy.

1896-1897: Marconi established the Wireless Telegraph and Signal Company.

1901: First transAtlantic signal sent by Marconi from Ireland to Canada.

1906: Fessenden transmits a program of speech and music. DeForest produces the Audion that allowed amplification of radio signals.
1910: First radio transmission from an airplane.
1912: Federal regulation of American airwaves begins. People had to be licensed and ships had to have a radio and trained operators.  

Information obtained from: http://transition.fcc.gov/omd/history/radio/documents/short_history.pdf
Video from: http://www.youtube.com/watch?v=kifC0HsYRy4

Fox-Hole Radio

Supplies need to make a fox hole radio:

• PVC pipe
• Copper wire
• Screws
• Screw driver
• Paper clips
• Headphone jack
• Razor blade
• Pencil head
• Small board
• Sandpaper

Tips before starting:

• Make sure all all coating of the copper wire is sanded off where metal meats metal.
• Make sure all wrappings are tight
• Make sure pencil is sharp
• Once built move the pencil around the razor blade and the paperclip on the PVC pipe until you pick up a signal.

Steps:

1. We started off by blueing the razor blade and screwing it to the board.
2. Next we put two screws on opposite ends but across from eachother into the PVC pipe.
3. We then had to wrap the PVC pipe with the copper wire and wrap the wire around the screws
leaving about one inch on one side and five inches on another.
4. You then take the five inch side and bring it straight down and wrap it around one screw and
then around the screw holding the razor blade down.
5. Next take a paper clip and wrap one end around a screw that is screwd into the board and take
the other end and shove it into the non-sharpened end of the pencil tip. (Make sure the screw is
screwed down close enough to where the pencil tip can touch the razor blade and the paper clip
is shoved into the lead not the wood.)
6. Bring a copper wire of the same screw as on the paperclip to you head phone jack and connect
it.
7. Next take a paperclip and wrap it around another screw close enough for the unfolded paper
clip to rub upon the copper wire wrapped around the PVC pipe.
8. Take a copper wire off of that same screw and connect into the other end of the headphone jack
and around a screw.
9. Leave a loop with the copper wire around the last screw in order to wrap the ground wire
around.