You may be able to tell if they're digital or analog based on their Emission Code (you'll need to click on the frequency or frequencies on their license in the FCC ULS for their license to see them). This should be accurate, but often if an agency upgrades their radios (like from standard analog to MotoTRBO for example) they may or may not update their license to reflect this change (they should and could be in violation for operating using a non-licensed mode, but they often don't realize this). They may go the other way as well, licensing for several different modes to allow them to properly and legally test each out prior to upgrading and fail to remove the others once they've picked a winner and migrated.
One other issue you may have is finding a license for them. There are two main reasons for this. First is that they may not be all that radio literate and not understand what's legal and what's not. They also may not need much from their radios and get away with those bubble pack radios you see in many of the stores or online. If they use the FRS bubble pack radios (or another of the license-free services), they won't have a license so there won't be anything to search for. Second, they may use a service provider that will lease them radios that use the provider's license so there won't be anything in the complex's name.
If they're analog, most inexpensive scanners should work. Most will have a "close call" feature that will help find an unknown frequency that's being used very close (or very powerfully) to your location. This can help find them when the license info or other frequency searches don't work.
Most digital scanners work on P-25 digital signals (
P25 CAI - The RadioReference Wiki), which is generally quite expensive so the chances your complex will use that type is quite low. They may still be digital but non p25 signals can't be heard using them (these include MotoTRBO -
MOTOTRBO - The RadioReference Wiki =, NXDN/IDAS -
NEXEDGE - The RadioReference Wiki -, or DMR note that MotoTRBO is a DMR offshoot -
DMR - The RadioReference Wiki).
If they use a service provider, they could use one or more conventional frequencies (
Conventional - The RadioReference Wiki) or could use a Trunked system (
Trunked Radio Systems - The RadioReference Wiki). Many trunked systems can be received on standard scanners. You just have to make sure what type is being used prior to buying. Both types can be found using the "close call" feature, but there's a huge caveat. Conventional channels will remain the same while on a Trunking System, the channels will likely jump around on all frequencies assigned to that trunked system. Not a major problem if you expect it, but if not you will be surprised that the frequency changes with most every transmission.
