Not sure if this is the right place, but I figured the Ham forumn would be the best place to start. I am looking for a scanner I can use to keep up with the goings on in our end of the county. I know that the Sheriff, PD etc are all using trunked systems, so I think that will require a digital scanner. Anyone have any suggestions?

No nefarius intent, just want to know why the ghetto bird is up, or where all the sirens are going.

Best check with someone local or maybe Radio Reference. I have 2 digital scanners that became basically useless when the local system converted over to the latest version of Motorola digital. It uses multiple antennas and switches often as the vehicle moves into another "zone". There is much fading on all signals. Also just about everything I actually want to follow is encrypted. If you go to RR, they often have a feed from the local system in your area and you don't have to have a scanner to listen in. Still no decryption though.

Depends on what your budget is, but if you can get a Radioshack PRO-652 you'll be in good shape. That's the one I use and it's a great scanner.

I know this isnt exactly an answer to the question, but...my local pd etc went to the motorola encrypted system.
I really dont have the bux for a pricey scanner right now.
I downloaded a free app and it can get them. Try "police scanner 5-0"

There are a couple of different variables in play here.

The first is a "trunked" system.  This basically means that you have a control channel and a bunch of other channels, the control channel tells the radios in the system which channel to use.  Without going into detail, a "trunking" scanner monitors the control channel and follows traffic.  It's more complex than that but that's basically what is going on.  

A simple "trunking scanner" will work for these systems - IF they aren't digital.  If they are digital, it will more or less work, but all you will hear will sound something like what came out of your old 56K modem.

The next variable is "digital"  To sum this one up, you need special software to decode digital signals.  This turns the 56K modem sounds into audio.  The vast majority of government radios are digital nowadays, from the school buses and garbage trucks to the police and fire departments.  There are some exceptions for volunteer fire and EMS, rural areas etc.  

To summarize, you can have digital trunked systems that require a "digital trunking scanner" to listen to.

The last is encryption.  This one should be pretty straightforward - if the digital signal is encrypted, you'll hear 56K modem sounds again unless you have the "key."  As this isn't really available to scanner users, you're more or less screwed if you are trying to listen to an encrypted system.  However, some places will have the ability to use encryption but may not do so on a regular basis so you can still listen in the majority of the time.

As the previous poster indicated, you can find most of what you need to know from radioreference.com

Use the clickable map here to find out more about the systems in your local area.

To find out if your local systems are encrypted (and to what extent) visit this page:  http://wiki.radioreference.com/index.php/Encrypted_Agencies


To answer your question regarding a good scanner, most digital scanners will be in the mid $300s new but if you search around on ebay and other sites you can find good used ones for $150-200.  I would reccomend a desktop model VS a handheld as a desktop model will be less prone to interference and related issues (opening squelch randomly etc)

Here is what radio reference is showing http://www.radioreference.com/apps/db/?sid=6565

It does not show Polk as being encrypted.

Also, so far none of the apps I have found support this area.

I have a Uniden Home Patrol 1 that I've been happy with.  It's kind of spendy, but it has a touch screen that allows you to enter a zip code or GPS coordinates to auto-configure the frequencies it monitors (versus having to research them and program the scanner).  It includes an optional PC program to update the channel info, create scan groups, and re-program the scanner, if you want to use that.



The Home Patrol 2 came out about a year ago and added support for APCO P25 Phase 2 encoding.  This is only important if your local agencies use Phase 2, otherwise the HP1 has the same features.




 

The current go-to is the Uniden BCD996P2, which will do anything that can be done,
more or less. I use the earlier version of the 996. Not cheap, but if the signal is
unencrypted, it's the scanner that will work.

Close call is a very nice feature to have as well.

Along a similar line, if I have located commercial digital freqs (Motorola), is there a less expensive way to monitor that digital traffic without buying an all encompassing scanner?

Yes.  
http://www.ebay.com/itm/NEW-USB-DVB-T-RTL-SDR-Realtek-RTL2832U-R820T-DVB-T-Tuner-Receiver-MCX-Input-/251240985308

Then, use DSD software in conjunction with VB virtual audio cable

http://www.rtl-sdr.com/rtl-sdr-radio-scanner-tutorial-decoding-digital-voice-p25-with-dsd/


Warning:  Frustration factor can be a bit high here.

thanks, I'll have to pull that dongle back out.

This is what I came to post. A couple RTLs and you can trunk follow just about any system

The systems the OP linked to are Phase 1 trunked up in 7/800 MHz. There is a mix of encrypted talk groups and clear talk groups.

Dsd and unitrunker will handle that fine, of course it won't break out the encrypted voice