A friend got me an HF upconverter and better RTLSDR dongle, and we were able to receive signals at 0.1 µV, which is pretty much as good as it gets, there's always about that much noise from the universe. The 8bit limitation generally isn't a huge issue, unless there are very strong local signals in the same capture bandwidth, in which case they'll likely fall well below the quantization limit.
You're taking 2,000,000 samples and down sampling by a factor of at least 40 in most cases, which gets you 5 more bits, before demodulating it.
Bear in mind that there are very stiff penalties for transmitting without a license, up to a year in prison and $10,000, for each offense. The FCC doesn't take kindly to pirate radio.
I'd like to see this conversation have evolved towards more specific & more technical.
Yes, a lot of hams are just crufty & computer averse, and that has kept back SDR. But also I think SDR so far leaves out a lot of the bigger picture needs, and I've been desperate to steer this thread away from "it's great" anec-data & into something more enriching & technically distinguishing.
This submission is so interesting in that there are plenty of radio devices here that have kept semi-conventional ham-ish form factors & capabilities, but which have SDR under the hood. My feeling is that less than 50% of that is software; that a lot of these radios are integrating analog signal chain systems normal ham gear would have like filters and amplifiers, that one has to pick & choose & build out - often with subideal results - to successfully replace ham gear with SDR.
This topic deserves better consideration. Maybe effective but depth is sufficient replacement to all these other typical analog doodads & gizmos; that could for sure be true. But I'd like a deeper exploration than 'we got great results & resolved a weak signal'. I think the $1300 LimeRFE exists for a good reason & purports to do good & valuable things we've want from good radio solutions. Rather than leave the conversation at some basic simple level like receiving a quiet signal, I think a deeper explanation & comparison would inform & help.
Quite a few of the things that distinguish "high end" radios these days are in terms of user interface, and connections to accessories. It used to be that crystal filters, the ability to select bandwidth, noise suppression, and other dedicated circuits made the radios better. With SDR, if you have sufficient bandwidth, bit depth, and dynamic range, you can do things that were previously $10,000 or more.
I was just trying to make the point that the cheapest, entry level, SDR (based on a test mode of the receiver chip) can do stuff that used to be expensive. The fact that a laptop can easily do a gigaflop makes it all possible.
Of course there are reasons to spend the money on a good radio. Lower noise figures, better clock stability, internal signal processing and UI. Dedicated knobs for functions are amazingly undervalued in terms of usability.
Getting an actually FCC Type approved amateur transceiver, gives good assurance of spur free output, and costs quite a bit to produce.
You're taking 2,000,000 samples and down sampling by a factor of at least 40 in most cases, which gets you 5 more bits, before demodulating it.
Bear in mind that there are very stiff penalties for transmitting without a license, up to a year in prison and $10,000, for each offense. The FCC doesn't take kindly to pirate radio.