Week signal FM mode?

[LB5KE]

Is there a way to improve the performance of a FM transceiver setup? That is EME uses JT44 to
dramatically increase the sensitivity of a SSB setup. Is there a mode that can increase the range
of a FM transmitter, by transferring voice or text digitally?  Or is FM unsuited for any week signal work?

[AC5UP]

Research the characteristics of the detector in an FM receiver, like capture ratio and limiting.

FM is a poor choice for weak signal work and if you have an all-mode HF rig you can demonstrate why: Tune to a frequency with no signal. Listen in AM or SSB mode. What do you hear? Band noise and maybe some static. Switch to FM. Noisy enough for ya'?

It takes a fair amount of signal to overcome the interstation noise inherent in FM receivers and although they've improved over the past 40 years or better they still won't dig a signal out of the crud like SSB can.

[N3OX]

Domino EX evidently works pretty well for weak signal FM, apparently about as well as SSB voice, just slower:

http://www.mail-archive.com/digitalradio@yahoogroups.com/msg26140.html

I haven't tried this yet but I will someday because it's a cool use of inexpensive hardware.