- #1
Faiq
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Homework Statement
The Attempt at a Solution
What should the bandwidth be over here? Confused since there is no mention of carrier frequency.
Optimizing Bandwidth in AM Modulation
- Thread starter Faiq
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- Bandwidth Modulation
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Homework Help Overview
The discussion revolves around determining the appropriate bandwidth for amplitude modulation (AM) in the context of audio signal representation. Participants express confusion regarding the role of carrier frequency and the calculation of bandwidth related to audio frequencies.
Discussion Character
- Exploratory, Conceptual clarification, Assumption checking
Approaches and Questions Raised
- Participants question the necessity of the carrier frequency in bandwidth calculations and explore the relationship between carrier and audio frequencies. Some suggest that bandwidth should equal the difference in frequencies, while others challenge this notion and seek clarification on the implications for single sideband and frequency modulation (FM) as well.
Discussion Status
The discussion is active, with participants sharing differing views on bandwidth definitions and calculations. Some have provided external resources for further understanding, and there is an ongoing exploration of how these concepts apply to both AM and FM modulation.
Contextual Notes
There is a noted lack of explicit information regarding the carrier frequency, which is causing confusion among participants. Additionally, the implications of different modulation types on bandwidth are being considered, highlighting the complexity of the topic.
What should the bandwidth be over here? Confused since there is no mention of carrier frequency.
- #2
Faiq
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is this correct?
For sound to be represented/interpreted by the receiver it will receive it as the difference in frequency of the carrier wave. Since the difference in frequency has to 4500 for max frequency of audio to be represented thus bandwidth is also equal to this. (Bandwidth = difference in carrier and audio frequency )
For sound to be represented/interpreted by the receiver it will receive it as the difference in frequency of the carrier wave. Since the difference in frequency has to 4500 for max frequency of audio to be represented thus bandwidth is also equal to this. (Bandwidth = difference in carrier and audio frequency )
- #3
TSny
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I don't believe this is quite correct. See if this helpsFaiq said:
https://www.electronics-notes.com/a...odulation-am-bandwidth-spectrum-sidebands.php
- #4
rude man
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I agree with #3, consider the entire span of frequencies at the worst-case signal frequency.
- #5
CWatters
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Faiq said:
It mentions a range of carrier frequencies.
- #6
rude man
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Right.
At this point I would direct you to post 2 & study the link's contents.
At this point I would direct you to post 2 & study the link's contents.
- #7
Faiq
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TSny said:
I was taught that bandwidth is Sideband - Carrier frequency. However here it is 2*(Sideband - Carrier frequency). Why is this happening over here? Does this also apply to single tone modulated AM waves? What about FM modulation?
- #8
CWatters
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Bandwidth is basically the width of the spectrum used (as per that diagram). So for a typical double side band broadcast it's roughly twice the maximum audio bandwidth.
That would be the case for a single sideband broadcast.
https://en.wikipedia.org/wiki/Single-sideband_modulation
Faiq said:
That would be the case for a single sideband broadcast.
https://en.wikipedia.org/wiki/Single-sideband_modulation
- #9
Faiq
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Okay and in FM modulation, the bandwidth is again twice the Fs-Fc?
- #10
CWatters
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With FM there are potentially more sidebands depending on the modulation index.
http://www.radio-electronics.com/in...y-modulation/spectrum-bandwidth-sidebands.php
Although in most cases the modulation index is small and only one pair of sidebands is used.
It's slightly more complicated for real world commercial broadcast FM radio stations because they usually broadcast in stereo and that needs more bandwidth for the Left and Right audio...
Edit: Tried to add a link to an image but it failed. Scroll down here to "Typical spectrum of composite baseband signal"
https://en.wikipedia.org/wiki/FM_broadcasting
http://www.radio-electronics.com/in...y-modulation/spectrum-bandwidth-sidebands.php
Although in most cases the modulation index is small and only one pair of sidebands is used.
It's slightly more complicated for real world commercial broadcast FM radio stations because they usually broadcast in stereo and that needs more bandwidth for the Left and Right audio...
Edit: Tried to add a link to an image but it failed. Scroll down here to "Typical spectrum of composite baseband signal"
https://en.wikipedia.org/wiki/FM_broadcasting
- #11
Faiq
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Thank you very much.
- #12
Faiq
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Thank you very much.
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