Nice to have another MIMO radio in the mix. When I first started experimenting with SDRs I thought "widest frequency range" was the spec to go for, then it bec

Nice to have another MIMO radio in the mix. When I first started experimenting with SDRs I thought "widest frequency range" was the spec to go for, then it became "widest bandwidth" was the spec to go for, and then it because "highest dynamic range" was the spec to go for. The truth is, depending on what you're interested in, any or none of those could be on your "must have" list. My journey went as follows; first I wanted to see as many different signals as possible from as many different sources as I could find. That suggested the wider the frequency range the more success I would have. But those sources transmit with a modulation and that modulation might consume a little (CW) or a lot (OFDM) of bandwidth. So more bandwidth, especially if something was using multiple "channels" in a space became key. But what if you can't hear what it is you are listening for? As digital devices the number of bits in your ADC really impacts your ability to deal with large adjacent signals in the band. You find yourself buying (or building) filters to knock back the US FM band, or a nearby TV station for example. For doing some bluetooth work I ended up with a band pass filter on the front end that killed off nearly anything outside the 2.4Ghz ISM band. Multiple inputs and outputs became a thing for me because I wanted to build an LTE base station, so I backed the LimeSDR and got one of those. There are interesting things to see when you have multiple receivers that are all running from a phase coherent local oscillator. You get this for 'free' when you have multiple receivers running off the same local oscillator. Lower frequencies are their own problem, the physics gets in the way. Fortunately it is well understood how to heterodyne DC to 200Mhz up into a range that these SDRs will operate. Of course that teaches you about things like phase noise and how it impacts your ability to separate individual channels. Lots of interesting things to learn, but it isn't just 'plug and go' with one box that can see "DC to Daylight"[1]. Filters, to keep out the signals you don't want. Amplifiers that bring up the signals you do want, and not too much noise. Bandwidth to capture the full signal and a bit extra. Enough sensitivity to pull out the modulation frequencies uniquely. And a fast enough DSP platform to turn that mush into the actual signal you are looking for. It is quite the pile of projects. [1] Daylight being visible light RF signals :-) Radios that cover say 1MZ to 25Ghz can easily cost $100,000 so they aren't really the stuff you'll pick up casually, but the industry is investing heavily and what you can do for as little as $100 (ADALM-PLUTO) is pretty amazing.