Dave Platt wrote:
In article .com,
wrote:

yes, that is what i meant. i didn't even know amplitude shift keying
existed.

am i correct about afsk being audio tones transmitted over FM, while
fsk is just alternating between two non-modulating frequencies?

That's pretty close, but not exactly on target.

AFSK can be used on top of either AM or FM. In amateur systems it's
most commonly used with FM.

FSK shifts the carrier frequency... a process which counts as a
modulation. The amount of frequency shift (in Hz) and the rate at
which you shift it (also in Hz) vary a lot from one usage to another.
There are both narrow-band and wide-band FSK modulations in use.

thanks! also, i was just reading about mixers... and getting confused.
i've run some matlab programs to figure out how you can take something
at frequency x and frequency y, and end up with an output of frequency
(x-y). one transmitter's mixer i saw took a 160mhz and 14mhz input to
get a 146mhz output. adding or multiplying them together certainly does
not yeild 146mhz. so how does that work?

thanks for the help!
jason