Min carrier frequency in Amp Mod.

[scubaman]

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.

 

[NascentOxygen]

Hint: we don't want any sideband frequency of 0Hz or less.

 

[scubaman]

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.

 

[rude man]

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.

 

[rezeew]

The minimum carrier frequency for an amplitude modulation system is twice the bandwidth of the message signal. This is known as the Nyquist rate and is derived from the Nyquist-Shannon sampling theorem. Therefore, in this DSB-SC system, the minimum usable value for the carrier frequency would be 2B Hz. This ensures that the message signal can be accurately reconstructed from the modulated signal.