Police Encrypted Radio detector

[balcone13]

Hi,

I'm looking to create some type of device that essentially scans a specific frequency (one commonly used by Police Encrypted radio) in my area.
The device would have a low range, approx 200-500m.

IF the device detects activity on that band then it would notify the user. (this could be further developed by giving a rough idea how strong the signal is notifying the user how close Police may be)

My understanding is that Police cars have a lot of radio equipment, the most common of which is the encrypted radio.

My assumption is that these encrypted radios constantly let off a ping/heartbeat (or something similar) which would be detectable by nearby recievers.

Based on the following: NSW Police (New South Wales) Scanner Frequencies and Radio Frequency Reference


I would be looking to check if there is activity on the 467.850mhz frequency.

I'm here for some expert opinions on how feasible this is as I have little to no experience with Radios.

I'm looking at connecting a NRF905 ISM 433-915MHz RF Transceiver Module to a Raspberry Pico Pi with a led display, I then write software that checks for activity on the 467.850mhz frequency. Since the range of this device is low, it should be able to detect any nearby police radio activity (or hopefully radios in general) and then notify the user.

For the record, I am not trying to listen to Encrypted Police radio. Just detect its presence within a specific range. - To my undertanding this is completely legal in Australia

Any help or knowledge would be greatly appreciated.

 

[mikewazowski]

Hi,

My assumption is that these encrypted radios constantly let off a ping/heartbeat (or something similar) which would be detectable by nearby recievers.

Unfortunately that assumption is wrong. Most likely, these radios only transmit when the officer presses the PTT button to make a call.

 

[Hit_Factor]

I remember executing a search warrant based on what was heard over a wireless transmitter on an informant. We found several devices that could have detected the bug, but the batteries were dead.

I wonder why this post made me think of that case?

 

[AB5ID]

Home | Target Blu Eye

TRACK Technologies introduces the new Blu Eye 2, the next generation safety system for motorists.

blu-eye.eu

Not available in the US yet. The company says they are working on a model for the US.

 

[AB5ID]

I'm not sure, but P25 radios may still be transmitting "pings" even when the PTT is not pressed. Can anyone confirm this?

It sounds like you are describing a device similar to a radar detector, but instead of detecting radar signals, it would use nearby police radios to notify users of police presence in the area.

This could be a major benefit to Radio Reference if such a device could load the entire database and actively monitor radios whether encrypted or not on repeater input frequencies based on the device's GPS location.

 

[ladn]

I'm not sure, but P25 radios may still be transmitting "pings" even when the PTT is not pressed. Can anyone confirm this?

Trunked subscriber radios "ping" the host without operator intervention. Non-trunked P25 radios don't.

 

[Project25_MASTR]

Trunked subscriber radios "ping" the host without operator intervention. Non-trunked P25 radios don't.

That's not entirely true. If the subscribers are using something like EFJ Affiliation, then they do perform the occasional data burst to inform the system controller that there is still actively a user on a specific talkgroup out there (much like you would see on a trunked system). That being said, for conventional operation its not exactly common to see a setup like that and even then, the data is unencrypted CAI data.

I think the OP is making the assumption that the entire transmission is encrypted with an encrypted radio when the reality is it is typically just the voice payload that is encrypted with the key info being defined in CAI data.

 

[ecps92]

Home | Target Blu Eye

TRACK Technologies introduces the new Blu Eye 2, the next generation safety system for motorists.

blu-eye.eu

Not available in the US yet. The company says they are working on a model for the US.

Hmm, guess I need to avoid those roads, because the CB Radio, FRS, GMRS keyed up next to my car, or the Ambulance advised Dispatch they were heading to Lunch

 

[AB5ID]

Hmm, guess I need to avoid those roads, because the CB Radio, FRS, GMRS keyed up next to my car, or the Ambulance advised Dispatch they were heading to Lunch

It's only listening for specific talk groups. So I think you will be okay Just because a channel/TG is encrypted doesn't mean you can't figure out it's actively in use nearby.

 

[rk911]

...For the record, I am not trying to listen to Encrypted Police radio. Just detect its presence within a specific

Curious...why?

 

[mmckenna]

It's only listening for specific talk groups. So I think you will be okay Just because a channel/TG is encrypted doesn't mean you can't figure out it's actively in use nearby.

Unless they encrypt the control channel, which is an option on newer systems.

Since it looks like the system the OP is wanting to try this on is conventional, then it just needs to know to look for the repeater input frequencies.
But unless the specific radio is actively transmitting, or beaconing it's position, or some other housekeeping task, it's going to be hard to make this reliable enough to be useful to know when the radio is nearby. Anything other than an active voice transmission is going to be very short, so the receiver would need to not be scanning a ton of channels for this to be reliable.

 

[balcone13]

Curious...why?

It’s essentially a police presence detector, radar detectors are illegal in Australia

 

[AB5ID]

After you get the detection figured out then you could determine direction of the transmission utilizing the same direction finding technique that is used with the kraken SDR. 🤔

 

[BinaryMode]

Yes, this can be done. NSW is using conventional frequencies but with digital voice known as P25... Well, IMBE/AMBE to be specific. At any rate, you can program all these frequencies in a software and using an SDR (Software Defined Radio) and a variable attenuator can be alerted to when this frequency lights up in your area letting you know someone is in the area. Though, I wonder if those frequencies have an input to the tower? They probably do and if so that is the input frequencies you want to be alerted on. Not the outputs you see here in the database. Not sure what the input to output offsets are in Oz.

I thought of doing a project like this myself, but in my neck of the woods it's a trunked system and it appears the RIDs (Radio ID) are not in the data on the input frequencies. If they were I could build a detector like you mention listening to the input channels and only alerting to RIDs belonging to the PD. That might be easier said then done though because I would have to log all PD RIDs over at least 2 weeks to create a database. I would even have the code activity monitor the dispatch talkgroup and logging any new RID that may come alone and careful to omit the console/s RIDs. I kinda do this now but with newly found talkgroups using an Autoit script and the Proscan history log while listening to all voice channels on three towers. Any new talkgroup not in my list taken from the database here at this site and it's considered new.

 

[GlobalNorth]

If you are worried about speed detection technologies, LIDAR, VASCAR, aircraft tracking, and even stopwatches are used in speed determining.

 

[paulears]

I cannot talk about Australia, but in the UK, the Officer worn radios do get remotely activated by the control room for updates and if an officer is sent a text or photo, the radio transmits as part of the process. Seeing this stuff is easy with a simple SDR receiver. The police radio system uses multiple transmit and multiple receive pairs, so once you find them, you can detect the presence of a police radio. Add DF capability, and you get presence and bearing. Signal strength you can, knowing the area, estimate. All off the shelf. We did have a police detector gadget when our system went encrypted, years ago. Oddly it soon vanished. SDR and DF gear easily available, but it needs operator skill to interpret the results. Probably a good thing criminals tend to be thick.

 

[buddrousa]

Sounds 100% useless to me unless you are a criminal trying to avoid the Police. I do not see a device like this getting FCC approval for the United States.

 

[KevinC]

Around 300 years ago I worked at CMC Stereo (they had 50+ stores mainly in the midwest/Texas). We had a guy buy a radar detector on a Saturday and he came back that Monday complaining it didn't it didn't work. He said he passed dozens of police cars and it never went off. We tried to explain it isn't a police car detector but he just couldn't comprehend that.

And reporting it didn't work for detecting radar wouldn't have surprised us as it was Maxon RD-1.

Vintage Maxon RD-1 Radar Detector Anti-Falsing Dual Superheterodyne | eBay

Vintage Maxon RD-1 Radar Detector Anti-Falsing Dual Superheterodyne. Condition is Used. Shipped with USPS First Class Package. Really cool looking vintage radar detector. Powers on!

www.ebay.com

 

[buddrousa]

I had one of those back in the day but my scanner was more useful.

 

[Dziub757]

Hi,

I'm looking to create some type of device that essentially scans a specific frequency (one commonly used by Police Encrypted radio) in my area.
The device would have a low range, approx 200-500m.

IF the device detects activity on that band then it would notify the user. (this could be further developed by giving a rough idea how strong the signal is notifying the user how close Police may be)

My understanding is that Police cars have a lot of radio equipment, the most common of which is the encrypted radio.

My assumption is that these encrypted radios constantly let off a ping/heartbeat (or something similar) which would be detectable by nearby recievers.

Based on the following: NSW Police (New South Wales) Scanner Frequencies and Radio Frequency Reference
View attachment 180737

I would be looking to check if there is activity on the 467.850mhz frequency.

I'm here for some expert opinions on how feasible this is as I have little to no experience with Radios.

I'm looking at connecting a NRF905 ISM 433-915MHz RF Transceiver Module to a Raspberry Pico Pi with a led display, I then write software that checks for activity on the 467.850mhz frequency. Since the range of this device is low, it should be able to detect any nearby police radio activity (or hopefully radios in general) and then notify the user.

For the record, I am not trying to listen to Encrypted Police radio. Just detect its presence within a specific range. - To my undertanding this is completely legal in Australia

Any help or knowledge would be greatly appreciated.

In the US I used to use a portable scanner that was set to scan the low power "mobile repeater" or extenders that were designed to retransmit from the police car to a hand held radio as a general situational awareness tool. As this was pre P25, I would get hits whenever dispatch was transmitting. Since it was a low powered signal and I was using a small antenna, a hit would tell me that there was a police car within a few miles of my location. Not fool proof but enough to improve my general awareness. Since my driving habits have changed, I no longer feel the need for this level of info.

I don't know anything about police radio in Australia, so don't know if this is useful info.