How Simple Radio Broadcasting and Receiving Work Using SDR

电子科技大学 格拉斯哥学院 2017级 李文翔

Abstract

Radio waves has become a very important medium for information transmission, as it can be modified easily and it transmits in the speed of light, which means that we can always receive the newest message and it changed the means of communication completely. SDR is a radio device which works with the help of software and in this article, I’ll discuss some basic functions of SDR and how it improve our daily life.

1. What is radio wave.

Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies as high as 300 gigahertz (GHz) to as low as 30 hertz. At 300 GHz, the corresponding
wavelength is 1 mm, and at 30 Hz is 10,000 km. Like all other electromagnetic
waves, radio waves travel at the speed of light. They are generated by electric
charges undergoing acceleration, such as time varying electric currents.

Naturally occurring radio waves are emitted by lightning and astronomical objects.
Radio waves are generated artificially by transmitters and received by radio receivers, using antennas. Radio waves are very widely used in modern technology for fixed and mobile radio communication, broadcasting, radar and other navigation systems,
communications satellites, wireless computer networks and many other
applications.

Radio waves in vacuum travel at the speed of light. When passing through a material medium, they are slowed according to that object’s permeability and permittivity. Air is thin enough that in the Earth’s atmosphere radio waves travel very close to the
speed of light.

We can use the method of amplitude modulation and frequency modulation to add the information we need into the radio waves. When a receiver gets the radio wave, it can analyses the message contained in the wave so that we can get the information accurately and swiftly.

So with the help of radio waves, we can have our information transmitted at a very fast
speed, and thus shorten the time delay