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I just found something interesting in the GMRS rules. From 95.1771: a. Each GMRS transmitter type must have the capability to transmit F3E or G3E emissions. b. Only emission types A1D, F1D, G1D, H1D, J1D, R1D, A3E, F3E, G3E, H3E, J3E, R3E, F2D, and G2D are authorized for use in the GMRS. Ok. F3E is FM (frequency modulation) voice. G3E is phase modulation voice; essentially the same as FM. So basically a. states that a GMRS station must be able to transmit FM. Then, b. adds to that. In addition to being capable of transmitting FM, a GMRS transmitter (because the transmitter is really the regulated part) may also have the capability of transmitting the other listed emission types. 1 and 2 refer to digital content. 3 refers to analog content, including voice transmissions. The third character refers to type of content, with E being telephony: voice or music. Of course music is verboten, so E means voice in the case of GMRS. So looking at the first character, the analog voice modes that are listed are: A3E, F3E, G3E, H3E, J3E and R3E. As already stated, F3E and G3E are FM voice. Here's the interesting part: A3E is AM voice. J3E is SSB voice. H3E and R3E are modified forms of SSB. DSB (Double Sideband, suppressed carrier) also falls under the heading of A3E, so that would be allowed as well. Conclusion: as long as a transmitter meets the rest of the requirements (including the ability to transmit on FM), there is nothing prohibiting the use of SSB or AM on GMRS. If someone would just build a Part 95 type classified multimode transceiver... The thing is, on ham radio it is not uncommon to communicate over paths of hundreds of miles, simplex, using 432 MHz SSB. It would seem that availability of a proper radio is the only thing preventing us from doing the same on GMRS freqs.

From my perspective, GMRS is reasonably equivalent to 440 FM ham radio, except the users in one extended family do not need to all be separately licensed. While full carrier AM would not be that useful, having the enhanced technology of SSB would be significant. I live in a fairly rural area, but at this moment am monitoring CB channel 39 LSB and can consistently talk to some stations 30+ miles away with me running legal power (12 watts PEP) with a Uniden Bearcat 980SSB rig. This is somewhat beyond what some might consider to be line of sight. I can sort of do it on AM, but SSB really helps. Same thing on VHF and UHF. The problem with SSB is that it is a bit more difficult for non technical folks and would significantly add to the cost of the rigs. I have talked to a station on 2 meter SSB with my 4 element beam at only 10 feet off the ground into northern Illinois from SE Wisconsin, if the other station has a fairly elaborate station with a high gain beam well up in the air. This is well over 100 miles simplex. And I can also talk to a station off the side of the beam around 25+ miles north of me when we had a three way. The FCC has loosened up the regulations on incidental use of ham radio for what we used to think of as commercial use. It would be completely acceptable to say, ask my wife to pick up some groceries via ham radio, but I personally would not make this an everyday practice. By the way, today is opening season of deer hunting and this has been the busiest I have heard the GMRS/FRS channels.

I think you may be missing the main point here. This is not a technological issue, it is about the basic nature of GMRS. GMRS was designed for short distance, reliable communications that can, and are, used for personal, family and commercial communications. Unlike ham radio, you can tell someone to pickup a six pack of beer, or make reservations at a restaurant for you. For those who want to experiment with different forms of radio communications, the ham bands are available for exactly that purpose. Adding unreliable modes to GMRS would totally defeat its purpose, raise the cost of equipment, and change the basic nature of the service.

Side Note: Our MyGMRS Moderator (spd641) has a system in Blount County that seems to have coverage from just north of Birmingham to around Hartselle along I-65. Not sure of the east-west coverage.