So, if I have a signal with a 1000 hz carrier, with a bandwidth of 50 hz,
you think I can sample it at just 150 hz and get accurate reproduction?
That's just wrong.

No, that's the whole point of this discussion.

You have to understand aliasing. The signal you want aliases
down into the baseband. Your anti-aliaising filter has
to get rid of all the junk you don't want. In this case it
includes the baseband. Since there is no baseband signal
(or other out-of-band junk) you can reconstruct the original
signal.

It's a common trick with software radios.

You do need some extra information that doesn't go in through
the A/D channel. That's the design of the system, in particular
what the anti-aliasing filter lets through.

Maybe the reason that this is so confusing is that you also need
that info the the normal/baseband case. But since that's the normal
case we don't bother mentioning it.

--
The suespammers.org mail server is located in California. So are all my
other mailboxes. Please do not send unsolicited bulk e-mail or unsolicited
commercial e-mail to my suespammers.org address or any of my other addresses.
These are my opinions, not necessarily my employer's. I hate spam.