Uniden recently provided a couple firmware updates for the SDS scanners. One of stated improvements was better reception of digital voice modes. Uniden didn't really clarify that statement, but on forums its believed to improved low signal performance.
I can confirm that for me, at a particular spot, on my particular SDS with my antenna hub antenna arrangement for UHF. I saw marked improvement on low signal DMR traffic. I was always able to receive it previously, however it took a while for the SDS to lock on. Coming back to that signal, I could tell the SDS locked on to the signal faster and this time started receiving a second site the organization has that is certainly obscured by terrain, when prior I could never receive it.
So, for me, the SDS firmware is a marked improvement when listening to low signal DMR.
On the topic of the SDS and weak signals, came across this video. https://www.youtube.com/watch?v=Z5bLbDeudIE While I don't have an R8600( I dream of one ) I was impressed with the comparison, and was impressed with the SDS200 performance on such a signal.
On Uniden scanners when the modulation of a channel is specified as “Auto” the scanner will do its best job to demodulate it with everything its got. However, if the Modulation is set to something specific, it will only recognize that channel if the modulation matches. If the channel is set to DMR, it'll only match when a DMR signals comes through. If the channel is set to Analog however, it'll match everything but only pass the FM audio. So if a digital voice mode, like DMR, is received, the channel will open up but just play you the “hammer” FM sound of the DMR signal.
This same behavior extends to Systems. If the System type is specified as something other than Conventional, It must match.
I've been scanning a system that used to be a conventional analog system. They have since upgraded to a DMR network. The conventional system( assuming modulation is set to auto ) will still scan it just fine, show that its DMR, and even expose the TGID & CC to the user and software( Ex: ProScan ). However, when you try to program a specific DMR System for it. You must have all the parameters just right or it won't work .
A similar system in the area changed from conventional to MotoTRBO Capacity +, Single frequency. The new system has to be programed as MotoTRBO Trunk instead of DMR One Site to get the scanner to recognize it.