Questions for each individual student: [14] AM and FM each work over a wide rang
ID: 2292380 • Letter: Q
Question
Questions for each individual student: [14] AM and FM each work over a wide range of frequencies. We have passed signals with carrier waves at 1 kHz (and even lower in the FM Circuits lab done previously). But the standards for commercial radio broadcasts in the US have FM carrier waves at a higher range than AM. Why is that? Check out the (simplified) specs for the frequencies that we can hear over AM and over FM commercial broadcasts. Don't get too distracted by single sideband, details of specs, modern maximization of the spectrum, etc. Just take a broad view of the concept they were thinking of when the standards were being developed. Here are some questions to guide you to an answer: Would it technically work if it were reversed (AM carrier waves at a higher frequency range than FM carrier waves)? Would the same goals be accomplished if it were reversed? Generally, what type of content is on AM radio stations vs. FM?Explanation / Answer
Amplitude modulation is the modulation of amplitude of carrier according to message signal, AM is meant for long distance communication if the frequency of carrier is very less, wavelength will be more and less the wavelength the chances of propogating along the surface of the earth by ionospheric reflections. whereas if the wavelength is less it cannot propogate along the surface of the earth, it is meant for line of sight propogation i.e., short distance communication. So, FM bands will be have higher frequencies than AM bands.
the bands can't be reversed, if we reverse the main agenda for distance of propogation will be affected.
As AM broadcast is meant for long distance and it can cover wider range of area, the content will not be more specific to region. whereas, FM broadcast is short distance communication, the content will be more specific to region of operation.
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