AM/FM on one carrier

You could do that, but it's more efficient to modulate a carrier with a constellation of phase:amplitude values, each combination representing a number (2-6 maybe) of bits. That's how most modems and fast RF data links work nowadays.

John

No one does that for all I know, but it would probably work if implemented correctly. For really slow data rates, you'll probably be okay. The AM part will be hard if the stations aren't fixed, and/or don't have really good AGC. The more common 2-bit method is this:

Q (10) | (11) O ++1 O | -1 | +1

-----+------+------+---- I | | O +-1 O (00) | (01)

You could call this diagram 4-QAM, but each point is equidistant from the origin, so just call it 4-PSK (QPSK).

Basically the points are orthoganal.

A "regular" IQ modulator will allow you to do this.

To reduce the amount of FM the IF has to handle

.--------. .--------. .--------. | | | | | | | | | IF | | AM | | RF -------- ----|---- -------- | | | | | | | '----|---' '--------' | '--------' | | | | .----|---. | .--------. .------. | | | | | | | | LO | -|---- LIMIT | | | | | | ------- FM ----- '----|---' | | | | | '--------' '--|---' | | | | | AFC | |---------------------------------------------- (created by AACircuit v1.28.6 beta 04/19/05

How does this do what you claim it does?