AM, FM and PM impose messages on carriers.
AM varies carrier amplitude (bandwidth 2f_m, simple, noise-sensitive), FM varies carrier frequency (bandwidth by Carson 2(Δf+f_m), noise-resilient), PM varies phase. Variants: SSB, DSB-SC, VSB. Demodulators: envelope detector, discriminator, PLL. Broadcast uses AM/FM radio.
FM broadcast bandwidth is about 200 kHz per station.
Analogue modulation puts a message on a carrier wave, which allows transmission at a useful frequency and sharing of a channel.
AM, FM and PM impose messages on carriers.
Analogue modulation puts a message on a carrier wave, which allows transmission at a useful frequency and sharing of a channel.
It changes the amplitude, frequency or phase of a carrier in proportion to the message, which allows it to be transmitted efficiently.
Noise mostly changes amplitude, and FM receivers can limit the amplitude, so the frequency information is preserved better.
Typical applications include broadcasting an AM radio station, transmitting FM audio with better noise immunity and using phase modulation as a building block for digital systems.
Study "Communication systems overview" first (topic 75 of 101 in Signals, Control & Comms). It covers the groundwork this topic builds on.
Modulation index. Carson's rule. Capture effect.
FM broadcast bandwidth is about 200 kHz per station.
The next topic is "Bandwidth and noise in comms", which builds directly on this one.
It is classed as Advanced in Signals, Control & Comms (topic 76 of 101). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Signals, Control & Comms.
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