Greetings! You're probably here because you want to know more about how to listen to police scanners to see what's going on around your neighborhood. There's a lot to know, but I'll try to walk you through your options, as well as explain the pros and cons of each.
This is far and away the easiest and cheapest option, but it does have some significant drawbacks. However, this is where most people start. All you need to do is go into your app store (Google Play or Apple App Store), search for "police scanner", and you'll likely find a few options available for free. Download the app, search for Anoka County, and you should be listening pretty quickly. You can also listen at a computer by visiting Broadcastify.
However, to understand the drawbacks you have to know how these work. All of these apps are built on top of the Broadcastify network. Essentially there are thousands of volunteers out there who have drastically more complicated setups (like mine, which I'll talk about below) who take the audio off of the radio waves and send it to Broadcastify. In turn, Broadcastify sends it either in their own player or to the app you're listening to. This works well most of the time, however, the fatal flaw here is if that volunteer's power or internet go out, the feed goes down for everybody because they can no longer transmit to Broadcastify.
There's another flaw to this method in that the scanner is only useful if you already happen to be listening to it. What I mean by that is, if you're sitting on the couch and you hear three squads go flying by, turning on the scanner at that point probably won't tell you much. The call already went out a couple minutes ago when you weren't listening. None of the apps that I know of have a way to "rewind" the feed and listen to what came in a few minutes ago.
However, at least for the latter problem, there is a solution. You can subscribe to Broadcastify Premium, which does give you access to archives. Everything that Broadcastify picks up from their volunteers, they save to their servers and you can "go back in time" and listen.
There's one more problem we need to discuss. Broadcastify has strict rules about what kind of audio they allow to be transmitted. Long story short: there's a LOT more audio out there on the radio waves than what you will hear on a Broadcastify stream. E.g. car-to-car, EMS, and tactical channels. None of which are allowed to be broadcast over a standard Broadcastify stream.
Buying your own police scanner is the next logical step for an enthusiast, but it's also the most expensive and somewhat difficult to program. I will caveat this with I do not own one of these, nor have I ever tried to setup a modern one, so take my advice here with a grain of salt.
Now before you go buying that cheap scanner off Amazon, you need to check to make sure it supports "APCO P25 Phase 1 trunking". This is the standard that Minnesota uses for all scanner traffic. Those $100 scanners on Amazon will not work. Your minimum investment here is likely going to be about $300-$400 to get one that will work. If I was going to buy one for myself right now, it would probably be this one.
The major pro of this method is that now you are no longer at the mercy of a Broadcastify volunteeer to get your audio. Your scanner is pulling them off of the radio waves itself and as long as you've got batteries, you can listen. You can also listen to those car-to-car, EMS, and tactical channels that Broadcastify hides (caveat: if the channel is encrypted, you still won't be able to hear it).
However, this method also has the same con in that you have to "already be listening" to catch the calls. As far as I know, they don't offer any kind of "rewind" function to listen to audio that happened a few minutes ago.
The other thing you need to know is that they have to be programmed. Modern police scanners work on a system of "talkgroups" (basically think of them like "channels"). You have to tell your scanner where the control frequencies are, as well as what talkgroups to pull in. This can get a little cumbersome, especially because Minnesota has thousands of talkgroups. However, as we discussed earlier, a Broadcastify Premium subscription is useful here, because it makes programming your scanner easier. I don't know the exact specifics of how it works with a handheld scanner, but essentially you can download a file that will program your scanner for you, saving you countless hours from hand keying them in. It's definitely worth the extra cost!
Now we're getting into the real complex stuff here, but what if you wanted to have all the pros with none of the cons? What if you want your own scanner, with rewind capabilities, and full car-to-car/EMS/tactical channels? What you need to look at is called SDR, or Software Defined Radio. Warning, this is the most complicated of the options and not really feasible unless you're really good with things like servers, Linux, programming, etc.
The way it works is you buy something called an "SDR Dongle" (and sometimes you need more than one, Anoka County requires two dongles). These are USB devices that take the radio waves in from an antenna and send it to a computer. Then you need to have a server running some software to interpret and save/transmit it.
To the left here you can see one of my servers. I actually have three different servers for this, this is my recording server. What it does is constantly listen to the radio traffic, every time there is a call, it saves it as a .wav file to the hard drive. Then I basically have a custom program that I've written to be able to go in and say "give me audio that happened on this date, from this time to this time". It then scans all of the saved .wav files, finds the ones that match that timeframe, and stitches them together into one listenable file. I cannot even properly express how long it has taken me to build that and nothing I could even come close to explaining here. I'm definitely into the hundreds of hours of programming time, giving it new options that help me find incidents faster. But if you want to start down that path, you want to check out a program called trunk-recorder..
My recording server is awesome, but it doesn't do so well with live traffic, you can't really listen to the file until after it's been recorded. So to remedy that, I actually have a second server, very similar setup, but instead of recording, it's only broadcasting it. Kind of my own private scanner. For that, I use a program called sdrtrunk.
Lastly, my third server is running another custom program I've written. To understand what it's doing, you have to know that basically, you have to be close enough to a tower to get the signals. If you live in Anoka County for example, you're close enough to an Anoka County tower and can pick up Anoka County traffic. But you will not be able to pick up Hennepin County. You're just too far from the tower. Even if you program your scanner to do it, it won't be able to find it. That's where my third server comes in, remember the Broadcastify streams I was talking about earlier? The ones you can listen online to for free? I actually have a server pulling in the Broadcastify streams for neighborhing counties that I might care about but I'm too far from to pick up with my antenna. If the Broadcastify feed is live, I'm recording it to this server and I can do similar things like query it for audio from a specific date and time. It also gives me some redundancy in case one of my other servers goes down, I still have this to fall back on. Cost-wise, these servers typically cost between $100 and $200 each.
Like I said, it would be way too difficult to explain the complexities of my servers here, but if you're interested in setting up your own and have questions, send me a message and I'll do what I can to help!