"How To Build a $19.00 Police Scanner"

[koØm]

Has anyone here successfully used a SDR to receive Trunked Tracking messages?

I started out here: https://sites.google.com/site/policescannerhowto/ (https://sites.google.com/site/policescannerhowto/). I also browsed the links provided for support information.

I have a working install of SDR# with a Trunk Tracking plugin but, when tuned to control frequency and, I am seeing digital signals but, the receive is not tracking and decoding them. I have two dongles, one for the "Signal" receiver and one for the "Control" receiver.

The article was written in 2013, in the process of trying to figure why my install wasn't decoding, I ran across this: If you’re a glutton for punishment, continue with this doc: (http://public-xrp.s3.amazonaws.com/docs/sdrsharptrunk.htm)


Back in my working days, I was the fellow that the folks called to untie knots that nobody else could not untie; I was not deterred by the warning.

But, Dayum, he was right.

I am soaking up information from http://forums.radioreference.com/software-defined-radio/265660-sdr-trunking-has-been-updated.html as you can see, this thread was started in 2013. I have spent multiple hours standing here with "Virtual Cables", Digital Speech Decoder, Trunk-Tracker; something small is missing, I have re-read the pages and retraced my steps.

It's been on hold for the last week, I guess I'm ready for more Sado-Masochism.

"Help!"

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[kb2vxa]

Oh no, you must be a sadomasochist if you think you can get anything useful from the Radioreference forums. If you really are a glutton for punishment keep at it, I gave up trying to reason with know-it-alls, pin heads, microminds and bricks around the time the thread started. I changed my bookmark URL from forums to the only useful part of Rat Reference, the database.

[koØm]

https://youtu.be/5N1C3WB8c0o

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[n2ize]

Oh no, you must be a sadomasochist if you think you can get anything useful from the Radioreference forums. If you really are a glutton for punishment keep at it, I gave up trying to reason with know-it-alls, pin heads, microminds and bricks around the time the thread started. I changed my bookmark URL from forums to the only useful part of Rat Reference, the database.

Very true. I don;t even remember what my username and password was over there. As far as p0olice scannning goes my old vacuum tube "vhf low" receiver works fine.

[koØm]

"Help!"

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This is not a "Plug-n-Play" project to be undertaken by the average "Appliance Operator".

I followed the 2 year old instructions to the letter but, the SDR would not performed as noted in the instructions; I retraced every step. I doubled checked my work. At this point, I backed up and started reading the information provided in the supplemental help links. After a minimum of 25 hours (over five days) of reading and fiddling around with the SDR# Trunk Tracking project, I walked away from it for a week.

Why didn't it work as it should? "Dumb-ass" me, I had the Laptop sitting on the desk with my large screen monitor, USB Keyboard, cordless phone and, cellphone; the two antenna were attached to the metal braces under the desk. The 800 Mhz signals were being blocked by the high noise floor created by all the crap on the desk. I moved the Laptop from the desk to another operating position and relocated the antenna about 10 feet away from the noise source and the damnable setup took off like a F-18 Jet.

<rant> "Open Source Code" -- Everybody and "his brother" seem to be able to write code and proudly document it on the Internet; there are plugin for this and plugins for that but, they are scattered all over the W.W.W. and, anyone is free to modify the code; this lead me down a number of dead end roads because what worked with one version of the code did not work with a different version of the code. Eventually, even I ended up modifying .xml configuration files and downloading 5 different release versions; substituting one with the other until I found the right combo. The problem: "Lots of dead limbs and rotten fruit hanging off the tree"; nobody around to organize the Incubator.</rant>

Seven days pass before I jump back in, for three days, I read endless links and I watched a YouTube Video on "How To" in "Stop-motion" to analyze every comment and move made by the author. All of the "Instructions" on the web seems to gloss over some very important points needed to make this thing work. By the fifth day of this cycle, I had it decoding individual digital feeds for the local trunked system but, the radio would not follow the trunking commands. I took another week off.

A couple of days ago, I started the final push; I entered the Control Frequency into the radio and noticed that it did not line up with the calibration of the radio. When I properly calibrated the SDR Dongle freq to the radio, the Trunk tracking started trying to control the secondary receiver but could not. The secondary radio was set to be parked on a control channel. I shifted the park frequency and, the Tracking control kicked in and started bouncing the receive frequencies around. The receiver dongle needed to be calibrated to the right frequency and now, the setup is working.

There is a sequence that the programs needed to produce output and function must be linked together with virtual audio cables and started up in a certain order to make it work; once running, you don't want to turn it off because it is not like a Uniden scanner that you just "Turn the knob" and get reception.

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[WØTKX]

Control Without Knobs. Kewl!

[koØm]

Oh no, you must be a sadomasochist if you think you can get anything useful from the Radioreference forums. If you really are a glutton for punishment keep at it, I gave up trying to reason with know-it-alls, pin heads, microminds and bricks around the time the thread started. I changed my bookmark URL from forums to the only useful part of Rat Reference, the database.

They have over 900,000 paid subscribers. If I dig deep enough and shift through the chafe and sludge, I'm pretty sure that I can come out of there with something useful; I'm hanging out in the Trunked Radio and Digital Speech Decoding forums, I haven't made it to the Amateur Radio section yet.

They are a little "High-and-Mighty" over there, one forum "Sticky" exclaimed, "If you don't know how to 'Compile' then, you shouldn't be in that particular forum" or even try to utilize the programs discussed in the threads.

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[koØm]

Control Without Knobs. Kewl!

Would really rather have a scanner with knobs to do the work of the two Linux based Digital Speech Decoders + Trunk-Tracking plugin + 2 SDR instances running at the same time but I'm not spending that kind of money on something that is receive only!

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[WØTKX]

Scanners are OK, but even at work they are using Internet feeds now for the communication center.

I never really "got' the scanner bug, but I sold/supported them with enthusiasm for customers.

[koØm]

Scanners are OK, but even at work they are using Internet feeds now for the communication center.

I never really "got' the scanner bug, but I sold/supported them with enthusiasm for customers.

They were "interesting" for a while, they allowed you to eavesdrop on the local neighborhood but, in 2010 the whole city and county went to a 800 MHz Digital Trunk system and every VHF and UHF scanner in the city became useless, people were giving them away.

I sold all mine on eBay.

I enjoyed the challenge of making the Software Defined Radio follow and decode the "secret" channels that the police use; the fire dispatch is especially informative, but I get pretty much of the same info off my Twitter feeds from the TV channels (you know that they are breathlessly monitoring the frequencies for "News").

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[kb2vxa]

"...in 2010 the whole city and county went to a 800 MHz Digital Trunk system and every VHF and UHF scanner in the city became useless, people were giving them away."
Smart hobbyists who know there's more out there than the local cop shop sure got a windfall bargain when the dummies who think that's all there is did that... LO firkin L!

[koØm]

Just throwing this out there:


Blah-blah-blah


But I was thinking for those of us with our HAM licenses (we're good guys too!), it could/would make sense if we were legally allowed to own a scanner that would decrypt the P25 signal. This is a big IF Uniden/Whistler/etc. even made scanners to decrypt the signal.


Anyway, I wanted to throw that out there in case it was a popular opinion and would maybe pick up steam and be lobbied to the FCC to make it happen (crossing fingers).



I understand what you are saying, but as a guy who runs a system that includes encrypted law enforcement channels, HELL NO.


Amateur radio operators don't have any need to have access to encrypted traffic. Amateur radio operators are no different than anyone else, the passing of a multiple choice test doesn't make them "special".


As someone who works on and around these systems, including inside a dispatch center, I've got to have all kinds of background checks, training, security rules/regulations, etc. The fact that I actually have an amateur radio license (General) doesn't mean anything to the people that I work for.


I fully understand that encryption is a issue for hobbyists, but keep in mind that listening to a scanner -is- a hobby. It should not be confused with being an actual public safety professional. I hold encryption keys for our system, and there is no way I'd give them out to anyone, even an amateur radio operator. I don't even give them to our officers. They get loaded in the radios when we program them, and that's it.


FCC isn't going to approve this. You are welcome to try, but I think you'll be disappointed.


And just because someone is an amateur doesn't automatically make them an upstanding citizen; just look up KB7ILD for starters....

Funny stuff from over there.

[KG4CGC]

So, it is some time later. Has the SDR revolution evolved?

I've been looking at this: https://www.amazon.com/Receiver-Dissipation-Communication-0-1MHz%E2%80%911-7GHz-Reception/dp/B08VF2FFX2/ref=sr_1_9?crid=1B2BTCKG0AAIL&keywords=sdr+radio+receiver&qid=1641241058&sprefix=SDR%2Caps%2C82&sr=8-9

[KG4CGC]

Or this: https://www.amazon.com/NooElec-NESDR-SMArTee-XTR-SDR/dp/B06Y1D7P48/ref=sr_1_12_sspa?crid=1B2BTCKG0AAIL&keywords=sdr+radio+receiver&qid=1641244963&sprefix=SDR%2Caps%2C82&sr=8-12-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyVUZQOEYxMzBOSTRZJ mVuY3J5cHRlZElkPUEwMDE4MTQ3WE5CU1A1SElPN0REJmVuY3J 5cHRlZEFkSWQ9QTA0OTQ0NzExOFY1VFhCWURDR0s3JndpZGdld E5hbWU9c3BfbXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm9 0TG9nQ2xpY2s9dHJ1ZQ==

[N8YX]

DSD Plus and SDRs are being used by a number of folks to track the trunked stuff.

What renders it moot is when an agency decides to encrypt ALL communications, rather than just tactical (i.e., SWAT or narco) comms. Something about "If you have nothing to hide..." come to mind?

Fortunately, there IS a fix for this. It doesn't involve decryption but it does involve a lot of community cooperation in terms of system development and infrastructure support. The proposal makes use of an intrinsic function of trunking systems and a function of a number of receivers that can receive the data streams.

First, ALL TGID/fleet/unit information must be broadcast "in the clear" in order for users from different agencies to subscribe to a common system. Their payloads - the actual voice or data traffic - can be encrypted without affecting the sharing capabilities of mutual-subscriber systems. Second, many scanners now incorporate a so-called "Close Call" function and will output signal-strength information (along with Close Call status) through their serial ports.

We take advantage of this and build a visualization system similar to the old Etherape network protocol display. A GPS-derived map of a user's location is accessible at an URL or through mobile app; receivers which support the required data feeds can be installed throughout an area. An analysis system similar to a repeater voter is employed to do dynamic triangulation of received signals. Obviously, the more receivers in a given area and listening to a given system the more precise the locating abilities will be.

Types of mobiles are identified by their TGID numbers and are color-visualized on the map. Higher confidence triangulations are brighter and don't fade with time; each occurrence of a mobile transmission merely boosts the location confidence factor in the algorithm. Mobile users will have the ability to provide unit verification (e.g., agency and patrol car number, truck or squad number) via the app when within range of a broadcasting unit, and a confidence ranking will be attributed to their data inputs based on co-user and RF ID correlation. This attempts to keep users "honest".

I'd like to see a PC app developed to interface the scanner...ultimately ending up with a Raspberry Pi which could be networked, connected to a scanner and left to gather data to forward along.

Should an area voluntarily broadcast their daily operations comms in-the-clear, I do not and will not support the use of this type of auto-locating setup. But for everyone else: We don't care what you have to say. We just care WHO and WHERE you are.

[KG4CGC]

Whoa!

[KG4CGC]

That all went WAY over my head.

[n6hcm]

yeah. I just bought a fancy scanner over the Xmas holiday. life is too short to fuck around with crap instructions,...

[K4PIH]

2 years more than that Hitler thing.

[WZ7U]

2 years more than that Hitler thing.

Prediction on the length of tRumps reign of terror?

[ad4mg]

tsk-tsk... politics in a technical forum... :icon_sad:

[WZ7U]

It's like whack-a-mole. I mean, :wtf: