Min carrier frequency in Amp Mod.

AI Thread Summary
In a DSB-SC system, the minimum carrier frequency must be greater than twice the message frequency to avoid zero or negative sideband frequencies. The Nyquist theorem is relevant here, indicating that the carrier frequency should be at least twice the bandwidth of the message signal. It is clarified that the lower sideband is treated as a spot frequency with zero bandwidth, not as having a bandwidth itself. The discussion emphasizes the importance of maintaining appropriate carrier frequencies to ensure proper modulation. Understanding these principles is crucial for effective amplitude modulation design.
scubaman
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Homework Statement



Given a DSB -SC system, with a message limited to B Hz, what is the minimum usable value of ωc or f0 (carrier frequency)

Homework Equations



Nyquist theory? Not sure how to apply.

The Attempt at a Solution



Only attempt has been through research.
 
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Hint: we don't want any sideband frequency of 0Hz or less.
 
What does this have to do with sidebands? A sideband could only have a bandwidth of 0Hz or less if Wc was actually less than Wm, no? I applied the nyquist theory (sampling) to this, and concluded that the carrier frequency must be at least twice that of the message frequency. Not sure if this is right though.
 
scubaman said:
What does this have to do with sidebands? A sideband could only have a bandwidth of 0Hz or less if Wc was actually less than Wm, no?

You're getting very warm.

BTW the lower sideband does not "have a bandwidth". It's assumed to be a spot frequency with zero bandwidth.
 
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