Sdr or sds? Maybe I'm missing something lol
The SDS series (SDS100 & SDS200) are Uniden scanners that can deal with simulcast systems.
SDR (Software Defined Radio) refers to the dongles that can be used, with a PC, to monitor & analyze many types of radio systems. There are several downloadable software programs that can be used, Some are free, a few have a fairly low cost, The dongles themselves are relatively inexpensive, much less cost than buying a high-end scanner. The downside is that, since these require a PC (they are not a stand-alone product like most scanners are), the use of a PC with these means it's more useful when used at a fixed location. That's not something that is readily portable. There is a
forum specific to using the SDR devices.
There are also the Unication pagers, as suggested in an earlier
post. I don't have one, but the comments are generally very positive as to how well these work. But the downside is that you are limited to monitoring one site, with up to 64 talkgroups. You can program additional sites, and additional scan lists, You can change sites & lists, but only monitor a single site and scanlist at a time.