I've been pondering the idea of making my own signal strength meter of sorts for RC FPV video.
My idea is to make a "module" that has an SMA input for the FPV antenna, and an SMA output that is fed into an RTL-SDR. The RTL-SDR would then be able to display the received signal and how strong it is. It would of course have some form of power supply, which would possibly be from a battery, since it's an RC-centric project, I'd likely be using a Li-Po battery for a power source.
However, FPV signals are 5.8GHz, way outside of the range of the RTL-SDR. This is where the "module" would come in, it would downconvert the 5.8GHz signal to something the RTL-SDR can handle.
I've been searching around for things and talking about it with a friend and here's what I -- and we've -- sort of come up with.
1. In the module, generate a 5GHz LO signal.
2. Mix that in with the 5.8GHz
3. Feed the resulting 800MHz signal out to the RTL-SDR.
Is this basically what would need to be done? The question now is how to choose components to perform #1 and #2, what devices to use to generate the 5GHz LO, the best way to mix them together, etc.
I also realize there'll be lots of RF design considerations I'll have to make such as impedance matched traces. I'll certainly be looking heavily into that and what I need to take care of in terms of the PCB design.
Finally, is this even achievable? Is this the sort of project that takes years and a team of engineers to accomplish? Or is this within the realm of a hobbyist with a decent chunk of free time?