A Question about Modulation?

Why must carrier frequency be at least 10 times greater than the modulating frequency (its one of the basic criterion set by FCC)


Reply as soon as possible.

Saad

What I know is that the nyquist condition for sampling is fs >= 2*Fin_max, to prevent aliasing.

but to be 10 times greater, I think that this may be used in oversamoling

It all depends on what kind of modulating technique you are using

The relation between carrier and modulating signal will fix the modulating index, which tell you in any case your bandwith

I suppose 1o times the modulating signal is required in order no to colour the modulation spectrum

i hope this will help you

bye

The higher the relation is, the easier the filters are.

If the relation between modulating frequency and carrier is lower, reveiver filters will have higher order.

This is another practical reason.

I think it will meet the nanoband communication requirement. If the modulation bandwidth is only tenth of the carrier frequency, it only occupies small bandwidth.

Yibin.