$19 Police/Fire/Medical Digital Radio Scanner Howto Guide

[harrysand]

I just put together a somewhat comprehensive howto on creating a Police/Fire/Medical radio scanner on instructables.com. It uses a single receiver and works pretty well for the price. Hope it can help anybody interested in putting one of these together!

How to Make a $19 Police Radio Scanner

 

[madmax14304]

Nice guide. Too bad none of the sdr software has pl tone squelch. Kind of kills the idea of using a dongle as a scanner.

 

[simplec6]

I really wish one of the SDR software could do pl tone squelch.

 

[sphipps]

I have a couple of USB TV tuners lying around and will give this a try. Looks promising...

Sent from my SGH-T989 using Tapatalk 2

 

[DaveNF2G]

You might not succeed. The dongles that are being used as SDRs are designed for European television standards and the software and firmware are aimed at those chips.

 

[KB7MIB]

Wirelessly posted (Mozilla/5.0 (X11; Linux i686; U; en-US) Gecko/20081217 Vision-Browser/8.1 301x200 LG VN530)

I've seen several threads here about people using dongles for ADS-B, MotoTRBO, and other scanner monitoring. Look in the aircraft monitoring forum, there's a thread about "Interesting aircraft...".

 

[sphipps]

You might not succeed. The dongles that are being used as SDRs are designed for European television standards and the software and firmware are aimed at those chips.

Yep... did some more studying and found that out. Got the right dongle coming via Ebay for $17 shipped and should be here by the end of the week. Can't wait to give this a try!

 

[sphipps]

Yep... did some more studying and found that out. Got the right dongle coming via Ebay for $17 shipped and should be here by the end of the week. Can't wait to give this a try!

Got the dongle and have SDR# / Unitrunker up and running. I think the hardest part of the install was trying to figure out how SDR# and Unitrunker communicates with each other in following P25. I couldn't find the log file that Unitrunker generates in controlling SDR#. Finally realized that my "appdata" folder was hidden and that's where I needed to go. That one took me a few hours to diagnose... but otherwise the instructions are "spot on" and it works 100% as described.

Saying this thing is "slick" is an absolute understatement. Those in the monitoring hobby who have not actually tried RTL-SDR are really missing out. If I can get this going... anyone can.

 

[AZScanner]

A caveat on your howto - some soundcards will not accept the min value of 48000 and SDR# will crash when trying to set this. In that case, you may need to set it to 44100 instead, but decoding will suffer. Despite this (my laptop's soundcard is one of these magic cards that chokes on 48000 for whatever reason) I can still get good decode out of DSD on it.

Good guide overall, though! Nice job!

-AZ

 

[kevinbarnes]

What Dongle for the US???

Steve,

Please save me a bunch of digging and let us know what dongle did you ended up using for the US?

Thanks,
Kevin

 

[harrysand]

I'm glad to hear you were able to follow the guide and get everything up and running! In the next day or so I will probably go back and revise it, maybe write a little more about the appdata folder, and address the potential sample rate bug.

Thanks for the input!

 

[harrysand]

Steve,

Please save me a bunch of digging and let us know what dongle did you ended up using for the US?

Thanks,
Kevin

I know I'm not Steve... But I live in the US and used this dongle with pretty good results:

Amazon.com: NooElec TV28T v2 USB DVB-T & RTL-SDR Receiver, RTL2832U & R820T Tuner, MCX Input. Low-Cost Software Defined Radio Compatible with Many SDR Software Packages. R820T Tuner & ESD-Safe Antenna Input, Guaranteed: Everything Else

and here:

NooElec - TV28T v2 DVB-T USB Stick (R820T) w/ Antenna and Remote Control - SDR Receivers - Software Defined Radio

 

[kevinbarnes]

Clarification on DVB-T dongle for US SDR

I contacted the vendor of the "Newsky TV28T v2 USB DVB-T & RTL-SDR " tunder and here is his reply.

Seems it should work for a US SDR but not TV...

"
I'm surprised no one has brought this up on the forum (the guys there tend to be pretty bright), but the unit will work just fine in the US as a SDR (scanner, etc.) They were originally meant for DVB-T reception, which is a video standard used in the EU and elsewhere. Of course, the unit cannot be used for DVB-T reception here in the US since the signals don't exist (we use ATSC for digital OTA signalling, which for technical reasons cannot be received by this unit). Does that clarify things a little bit? If you have the chance please post the same in the forum so that those reviewing the forum won't be confused or misled.

"

Kb

 

[DaveNF2G]

Steve,

Please save me a bunch of digging and let us know what dongle did you ended up using for the US?

Thanks,
Kevin

As an SDR, a dongle using the RTL2832 chip will work. It doesn't matter what country you are in.

As a TV receiver, you need something marketed as a "PCTV" that is compatible with the North American ATSC/NTSC standards.

 

[KC4RAF]

Thanks for that info 'harrysand' about what to buy.

I just did an order from the NooElec site. Will try it out. Not interested in any TV action on the computer, just the SDR side of that dongle. Thanks again.

 

[sphipps]

Please save me a bunch of digging and let us know what dongle did you ended up using for the US?

Here's the Ebay link to the one I bought for $17 shipped. Ordered it on a Monday from San Diego and got it here in Missouri on Wednesday... so they're really fast.

New USB DVB T Rtl SDR Realtek RTL2832U R820T DVB T Tuner Receiver MCX Input | eBay

I'm definitely no expert on this... but I'm quickly finding out that the "bottleneck" of this setup is decoding of digital systems. You need to have a fairly fast computer with good specs to get solid decoding. Anything older than a high end dual core probably isn't going to "cut" it. If you experience decoding errors... only run SDRSharp, Unitrunker, and DSD closing everything else including explorer.exe in Task Manager. That seemed to help me the most. You also need excellent reception. DSD is extremely "picky" as to what it will decode.

I'm getting about a 75% to 80% success rate on P25 decodes using this system. Not perfect... but absolutely outstanding for a $17 investment. I can certainly follow what's going on. If we can come up with better ways to troubleshoot decoding... then this thing will really "shine".

If you just want to use the dongle and SDRSharp as a general coverage receiver, then it will work just fine for that on any modern PC. My 6 year old Gateway laptop with a 1.6 GHz dual core works great for this... but it can't handle decoding. My fairly new Dell desktop does a much better job decoding.

SDRSharp is being tweaked and improved almost on a daily basis. Who knows where all of this will lead over the next few months.

I'd like to learn more about this... so everyone PLEASE post your findings and results once you get your dongles going!

 

[shortwaver]

Thanks for putting this guide together. You obviously dedicated some time to doing it and it is well documented. I can't wait to try it.