For AM detection you can also use a synchon detector.
For FM you can also use a Phase Locked Loop detector.

How is PLL detection different then product/mixer/superhet detectors for FM.

Are they easier to build ? Seems to me this is just another form of the other detectors.

As for the synchon detectors I looked those up and it seems these are just a version of product detection for AM.


Also curious

If you had the same carrier wave and modulated it 3 different ways AM , FM , PM . Would the AM and FM not interfer but the FM and PM interfer. Seems to me you can us the same carrier to modulate it with FM and AM so that both AM and FM recievers (if they where tuned into the same carrier frequency in theory would beable to recover the voice/data modulated on this wave because it is in both the amplitude and frequency variations and none of these effect the other unless the detector is sensitive to both)

But I am unsure if modulating the same carrier with FM and PM modulation could be done.
I think only AM and FM or AM and PM can be done in combination?
Curious though.

Note I am talking about analog modulation the digital equvialent would be ASK , FSK , PSK , and the combinations would be QAM ( combo of ASK and PSK ) but I don't know if it is possible to do a combination of FSK and PSK?
Obviously you could do ASK , FSK.

So I would think analog or digital can't do PM and FM modulation combined but the 2 other combo's can be done and are done for both analog and digital.

Maybe you can do PM and FM combo mathematically out on paper but I would think practically this would be to interferenceee.

Input

 

A phase locked loop uses a VCO and negative feedback to keep the VCO locked onto the carrier frequency. The error control voltage is demodulated FM. Because it isn't using typical RF techniques it is actually a lot easier to build, you just adjust the center frequency of the VCO to a reference voltage, the rest follows with no real tuning involved. A simple phase detector is a XOR gate, a balanced mixer is also a form of phase detector.

You start getting into other modulation techniques I'll bow out, I can't be of any real help there. You can have a FM signal encoded as part of an AM signal. Oddly enough, it is also a discrete signal on the spectrum (remember AM sidebands are images of the modulation).