2007-01-02 12:14:03 · 8 answers · asked by sharma g 1 in Science & Mathematics ➔ Engineering
Let me give you an example.
Suppose you are sitting on the ground in Washington D.C. and you want to talk to someone in an airplane flying over Germany.
You could try yelling as loud as possible, but that wouldn't work. They wouldn't be able to hear you.
Better would be to talk into a electronic communication device, known as a radio, that would modulate your voice-frequency signal onto the carrier-frequency of the HF radio.
Then the electro-magnetic waves could carry the signal to the aircraft where it would be detected and demodulated so that the guy in the aircraft could hear what you're saying.
2007-01-02 13:48:32 · answer #1 · answered by Anonymous · 0⤊ 0⤋
modulation : it is the process in which some characteristic parameter of the high frequency carrier wave is vareid lenearly in accordance with the amplitude of the message signal.
need for modulation are
1. velocity = frequency x wave length but antenna hieght should be greater than the 1/10 of the wave length so we have shift the frequency to higher level such that we can reduce the wave length hence antenna height
2, for frequency division multiplexing the signals by shifting or modulating the different carriers to different ranges
2007-01-06 00:34:11 · answer #2 · answered by naren2006 1 · 0⤊ 0⤋
Modulation is essentially the ability to put your 'signal' onto a carrier wave.
In other words, when you hear music you have a carrier wave....like a train of sorts. It carries no information.
The music signals are overlayed (for lack of a better way to say it) onto this carrier wave. The carrier wave carrier the music (or whatever) information to your receiver (speaker, monitor, television, etc etc), which performs the necessary translation and places it into a form you can understand.....audio, visual, both, etc.
No 'modulation' = no information.
2007-01-02 12:23:42 · answer #3 · answered by Anonymous · 1⤊ 0⤋
Low frequency signal is hard to transmit by air, so it needs to modulate the high frequency to be transmited
2007-01-02 13:01:04 · answer #4 · answered by JAMES 4 · 0⤊ 0⤋
The "need" for it is to control amplitude. Some things are too quiet, some things are TOO LOUD...modulation allows quiet and LOUD things to co-exist in relative harmony.
2007-01-02 12:23:24 · answer #5 · answered by Jason 2 · 0⤊ 1⤋
modulation is used in electronics & computers. what is called digital design is basicly modulation.
2007-01-02 12:18:30 · answer #6 · answered by jackie 1 · 0⤊ 1⤋
You need to control the amplitude of the carrier,
or the frequence (FM )
2007-01-02 16:46:55 · answer #7 · answered by gjmb1960 7 · 0⤊ 0⤋
i think for a fractional control not step control
2007-01-02 12:46:45 · answer #8 · answered by ckd_xl 2 · 0⤊ 1⤋