Are there frequencies in Vegas even the latest digital scanners can't pick up?
From a purely technical standpoint that would be a "no" since a frequency is just a frequency in the long run and all modern scanners, save for a few, will have pretty wide coverage meaning if something is transmitting, the scanner/receiver will pick it up.
Now, if by "digital scanners" you mean a device, a scanner/receiver, that has the capability to receive (already covered that just now)
and decode the digital protocols being used (P25 Phase I, X2-TDMA, Phase II, DMR/MOTOTRBO, NXDN, ProVoice, etc) that's another thing altogether.
So, while modern scanners can receive most any currently used frequency, sometimes the content being transmitted on said frequencies are "digital" in nature (it's all analog in the long run) and carrying content that needs to be decoded and not every scanner is capable of such action. In fact, there are only 3 scanners available today that cover the most frequently used digital protocols (those being P25 Phase I, P25 X2-TDMA, and the newer P25 Phase II variant) and those are the GRE PSR-800 (no longer made and getting rarer and more expensive by the day I think) and the two new Uniden scanners, the BCD436HP handheld and the BCD536HP base/mobile.
Nothing on the market today in terms of scanners will decode:
- DMR/MOTOTRBO
- ProVoice
- NXDN
- D-Star
and whatever else might be out there but, with a discriminator tap on a given scanner and a laptop/desktop computer using some software like DSD or DSD+ you can actually monitor those other digital modes with a little effort - only one still not available is P25 Phase II but I suspect sooner or later we'll see a software-based decoder that will handle it (and I can't wait when we do since some systems in my area will be moving to Phase II in the next 1-2 years).
Of course, you can always get a $10-20 "cheap USB TV tuner" and do SDR with DSD or DSD+ and decode all that stuff (again, no P25 Phase II so far) pretty cheaply.
