15.219 and 15.239 do not specify the modulation scheme to use

You cannot listen to an SSB signal, suppressed carrier, unless you introduce said carrier on your receiver.  Some portable radios that also have shortwave bands can receive SSB signals in the X Band, but they certainly are not pervasive.  Otherwise, all you will hear is the typical duck quacking sound that SSB makes.  There IS a way to receive SSB with 2 radios tuned to nearly the same frequency (one listens, one introduces the carrier) but I doubt that many would accept needing 2 radios to just listen to a single signal.

The problem as I see it is how to legally transmit an SSB signal in the X Band.  I suppose you could find an amateur radio QRP SSB transmitter kit and modify it for transmitting just below the 160 meter band, also making sure that the input power to the final stage is 100mw or lower.

The more I think about it, the more interesting this experiment sounds.  I wonder just what the range could be on such a device, particularly to a good shortwave receiver.

Overall, though, I think it would be easier to experiment on the 13.560 ISM frequency.  Easier to find potential transmitters, and potentially much longer range.

To add to the list, I have wondered if you could amplitude modulate and frequency modulate the same carrier so as to send two separate programs to two different kinds of radio.

I would expect the fm demodulation would suffer when the transmitted carrier was at minimum amplitude during the am modulation process ?

Paul.

Yesterday while doing some Shortwave scanning from 2Mhz to 29.995 I found that 3Mhz was alive, 71000 Mhz and the high end had amateur Radio activity (Still have to get that 9 volt for the BFO for the Grundig). The moral was that I got around 13.560 Mhz and I've heard data carrier there. There is some shortwave activity I did hear through the 13 Mhz band. Is 13.560 the only legal frequency for Shortwave ir is that just the official frequency of the Big Talker Shortwave Transmitter? We may be on to something here. I've checked that frequency for any sign of a Shortwave station running part 15 just to see if I could hear a distant station under the right conditions.

Just an opinion and not to stir anything up here remember I'm calming down.  I'd think the FCC though they don't state it would rather we use the modulation indended for the band we broadcast on.  And intended for us to keep using certified AM or FM transmitters not counting kits.  But opinions may very.

The reason 13.560 MHz is talked about is because it allows more field strength than any other shortwave frequency for Part 15.

There are several other SW frequencies that allow slightly less field strength, and the whole SW band from 1710 kHz to 30MHz is open, but at a power level so low it would be meaningless to try it.

You could amplitude and frequency modulate the same signal, simple VFO transmitters do, like the old phono oscillators. Thinking about it, if the signal is strong enough at the receiver, and you don't modulate the AM part fully, the FM signal should work well, but probably not the AM.

We were talking about AM stereo, that uses phase modulation of the station's carrier for the L-R difference signal, so that's a sort of AM-FM signal it would seem.

The glorious thing about part 15 is we aren't limited in what mode we can broadcast in.

Remember Part 15 was and is for experimentation. I have always wondered if FM would work well in the medium wave band. FM seems more resiliant to noise, but I am unsure if this is just a characteristic of VHF vs. MW. That being said the NFM broadcasts in the 20mhz area used for STLs sounds fantastic.

That being said, heres the answers to your questions:

SSB on AM reciever: The Classic "wah wah quack"

FM on AM Reciever: Garbled mess, think the Talking House Transmitter's garble on the fringe.

AM on FM Reciever: White Noise.

Basically on an FM reciever anything recieved not in frequency modulation will just come out as white noise.

"In terms of range per watt, depending on local noise, SSB > AM > FM."

Actually I'd put this, SSB > Narrow FM > FM > AM. Although in a zero noise environment AM would likely come ahead. Also some law enforecement swear NFM is no where near as good as Wideband FM.

Mighty 1650 I remember around the hear 2001 I did mess with my uniden scanner and was listening on AM. I got just around 25 Mhz and I heard what sounded like FM so I switch modes and vala I heard an STL from WFLA in Tampa, Florida. It was skipping in really nice in Lansing, Michigan. I listened for quite sometime before the signal faded. I picked up some other STL's in Florida and was amazed they used those frequencies. The sound was great and enjoyable in fact. It sounded like 29 FM 10 meter ham. It would be interesting to do NFM on the AM band to see what the range would be like and rather we could get through the noise floor with it. Problem is I don't have a way to actually receive an FM carrier down there. The Grundig has an IF output so there may be a way to do it with that.

From Florida Low Power Radio: 25,870 (LPR) WFLA, Tampa; inactive, not heard since late 2002 or early January, 2003.  This remote broadcast cue unit operat(ed) 24 hours-a-day, relaying News Radio 970 WFLA (970 kHz) audio in real time (without the seven seconds delay on locally-originated programming). The station occasionally boasted this as their "shortwave" frequency--and indeed it is sometimes heard worldwide--E-skip and maximum usable frequency allowing. Readily QSL's as well. Mode is narrow band FM.

KLDE out of San Angelo/Eldorado Texas also broadcasts its oldies format 24/7 on 25.910 kHz in FM mode.

I did pick two frequencies in the 25 Mhz area and now I remember that was the frequency of WFLA.  It came in clear.  Tuning up towards the channel jumpers who went below channel 1 on CB and who had the Galaxy exports that could transmit on FM I heard another station as well.  Again I was amazed at how clear the signal was and could listen for quite some time.