Amplitude modulation is where a constant carrier is modulated by the signal, so that the envelope of the carrier represents the signal.
Frequency modulation is where a constant carrier is modulated by the signal, so that the frequency of the carrier represents the signal.
Phase modulation is where a constant carrier is modulated by the signal, so that the phase angle of the carrier represents the carrier.
For a sound wave coming from a Flute for example, frequency modulation (FM) would be changing the "note" you play at a fixed volume, whereas amplitude modulation (AM) would be changing the "volume" of the fixed note you play.
I use sound as an easily understood vehicle, however this applies to a wave in any medium.
Information can be encoded on a wave by changing the "notes" (in a continuous fashion, like in a Trombone. i.e. FM) or changing the "volume" (i.e. AM). There are other ways to encode information in a wave too, but those are a distraction for the purposes of this AM/FM question.
To put a small bit of math on it:
W(t) = A * sin ( F*t + P )
W is the wave amplitude, t is time. FM varies F, AM varies A, P (phase) is an arbitrary constant for the purposes of this question, however it too can be modulated. You can graph W(t) on a computer and see what changing A and F does, as t goes from 0 to some time T in small increments.
There are many tradeoffs in choosing how to modify a base wave (or waves) to transmit information that can be faithfully decoded at a receiver over a communications channel (for example free space, or a telephone line, or a fiber optic cable etc)
Frequency modulation waves have higher frequencies and more energy than amplitude modulation waves. They pass through the ionosphere instead of being reflected back to Earth. Thus, frequency modulation waves do not travel as far as amplitude modulation waves. So, if you go on a long car trip with an FM radio station tuned in, you may quickly lose reception of the station. But frequency modulation waves are usually received clearly and produce better sound quality than amplitude modulation waves.
Phase Modulation :http://en.wikipedia.org/wiki/Phase_modulation
Amplitude Modulation :http://en.wikipedia.org/wiki/Amplitude_modulation
cheers!
because recieving hardwere is complex pm is used in digital synthesizers
in amplitude modulation amplitude of the carrier wave is changed with respect to the intensity of the modulating signal where as frequency and phase of the modulating signal is kept constant
modulation:- the characteristic varying in Carrier signal,according to the message signal
if amplitude is changing then amplitude modulation
FM stands for frequency modulation. The definition is: when the frequency of the carrier wave is changed in accordance with the intensity of the signal, it is called frequency modulation. In frequency modulation, only the frequency of the carrier wave is changed in accordance with the signal. However, the amplitude of the carrier wave remains unchanged.
I beleive what you are referring to is a modulated signal which can be either amplitude, frequency or phase modulation. As with radio signals carrying information: AM, FM or PM.
Yes. There's no connection between frequency and amplitude.
Frequency and amplitude.
Amplitude is how loud sound is and does not change a sounds pitch. They are independent.
AM - Amplitude Modulation FM - Frequency Modulation
Normal frequency range for amplitude modulation is 550kHz to 1610kHz
am is amplitude modulation, fm, frequency modulation
because noise usually changes the amplitude not frequency.
Frequency modulation have some advantages over amplitude modulation, FM is not sensitive to the amplitude noise, and have high efficient use of transmitted power
Amplitude of the (high frequency) Carrier signal is varied with respect to low frequency of message signal is called amplitude modulation. Frequency of the carrier signal is varied with respect to low frequency of message signal is called frequency modulation.
Amplitude Modulation (AM) Frequency Modulation (FM)
amplitude modulation
amplitude modulation & frequency modulation
amplitude modulation is where we modulate our signal with a carrier signal amplitude changes but frequency remains constant in amplitude modulation
the frequency range of an am wave is 20herz to 20kilo herz
AM = Amplitude Modulation. FM = Frequency Modulation