There is a version of the SDR Play that has two receivers and two antennas in one enclosure. Now we need a genius software writer to pursue these big ideas.
Antenna/Receiver No 1 would be an AM designed to function as a professional part 15 Frequency/Modulation Monitor.
Antenna/Receiver No 2 an FM functioning as a professional part 15 Frequency/Modulation Monitor.
Now the piece of cake...
A SDT software defined TRANSMITTER designed to perform as a Part 15 transmitter with every imaginable function adjustable and definable. The ultimate transmitter!!
Let's plan lunch.
I wonder if you could get a Part 15 SDT certified?
Both the FCC and ISED (Industry Canada) are sticklers about not having any internal adjustable parts that could increase field strength. By definition, all you have to do is to change the software in the SDT and you can change pretty much anything. Bandwidth, field strength, even transmission mode.
You'd certainly want to prevent any hacking. And I'm sure that both the FCC and ISED are savvy enough to know that a developer could put in all sorts of software back doors to allow 'privileged' users to change things. Although I suppose that's true of some of the certified transmitters today, which are based on chips and somewhat programmable.
An interesting concept.
There are full SD Transceivers today available for the ham bands. I own 2 VHF/UHF handheld transceivers (transmit in FM only) that have flashable firmware, and enterprising hams have distributed modified software that will cover HF as well, in various modes such as AM, DSB (double side band), CW, etc. They've also added features such as built-in spectrum analyzers. I bet you could take one of those, and turn it into a Part 15 FM broadcast band transmitter, and probably with minimal hardware changes. I would imagine you would need to change the filtering, but the 2 meter ham band isn't all that much higher than the FM broadcast band.