Friday, June 3, 2011

Stereo ..... Frequency Levels

What is a stereo ? 
i came across this question when trying to understand the Radio data system and how it works on . while reading this (RDS operates by adding data to the baseband signal that is used to modulate the radio frequency carrier. The baseband signal consists of a number of components. Firstly there is the mono audio consisting of the left plus right (L+R) component that is transmitted at the normal audio frequencies up to 15 kHz. The stereo difference signal is then amplitude modulated as a double sideband suppressed carrier signal at 38 kHz).
ok . there are two kind of stereos

Audio stereo and Video stereo

both refers to a similar term

Audio stereo : stands for sound being dividied into two separate channels (speakers) for the aim to support the sound simultaneously in two speakers to also provide the chance to mix different sounds. the idea is inspired because a human has two ears trying to make it realistic as much as possible. such as in a movie when a car passes the audio is divided in a way to give a sound (Doppler) from an ear to ear as the car is realistically passing in front of the audience.

Video stereo : two saperate images of the same objects, being taken slightly different in order to simulate 3D view for human eye. there are many different ways to get to the 3d effect which i wont discuss here

here is a good illustration klik here
Frequency levels
there are three weeks ahead of me to end the third year of applied communication engineering , one year ahead of graduating and i still do not know under what frequency lies the low , high frequency!!!! but i do know that microwave(not the range but the one u use ate your house) is the most used frequency in the world 2.4 gigahertz 

Free-space Wavelengths
Very Low Frequency
9 kHz - 30 kHz                               
33 km - 10 km
Low Frequency
30 kHz - 300 kHz
10 km - 1 km
Medium Frequency
300 kHz - 3 MHz
1 km - 100 m
High Frequency
3 MHz - 30 MHz
100 m - 10 m
Very High Frequency
30 MHz - 300 MHz
10 m - 1 m
Ultra High Frequency
300 MHz - 3 GHz
1 m - 100 mm
Super High Frequency
3 GHz - 30 GHz
100 mm - 10 mm
Extremely High Frequency
30 GHz - 300 GHz
10 mm - 1 mm


  1. Stereo give more sence of depth for the sound, more then mono

    more details can be found in this link