this post was submitted on 24 Jul 2023
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We use the same licensed VHF network at work for the last 30 years. Ever since our local cops switched to 'digital', 'encrypted' radio comms, we regularly pick them up on our VHFs across the entire district, regardless of what frequency we are on.
It's like their whole thing is leaking across the bands, which should not be possible given that it's encrypted but here we are. If it were anyone else, we'd be pursuing them for abusing the frequency band that we pay for but it doesn't feel like a battle that we want to start.
Maybe don't start the battle, but instead get a private citizen to notify the FCC:
https://www.fcc.gov/sites/default/files/interference_with_radio_tv_and_telephone_signals.pdf
We have a similar organisation to the FCC that deals with these matters. I will take this up with our radio specialist first though.
The bit that has me scratching my head is that it is our analogue VHF system that is picking up these communications.
All emergency services are supposed to have moved to digital, encrypted channels and yet I am sitting here listening to the police despatch co-ordinate units to chase an agitated man with a bat as we speak. It's happening daily, especially early in the morning but it just doesn't make any sense to me.
Unless some part of their network is still analogue, we shouldn't be hearing anything.
I do not know enough about the technical side of these technologies to understand this, I just use them regularly.
We have an extensive network of private repeaters set up all over the state on our own land. I just hope it is not us that are somehow causing this problem. We have the requisite licenses for all of our bands and nothing has really changed for us. Trouble only started when they went digital.
Yeah it's local. They name local streets and towns.
Digital is noisy af. When we switched from analog to digital at work (same radios, just a software upgrade) they started to interfere with loads of equipment.
It also seems kind of a bad choice for emergency services.
I know when we trialled going digital for fire response at my old company it was an absolute failure.
At least with analogue when there was interference from smoke or terrain, we could mostly get the gist of what had been said.
With digital it seemed to either work or not work, there was no in-between.
It was more akin to transmitting a short audio file or recording than a live communications medium. Not a single one of us thought it was an improvement on our existing system but of course they rolled it out anyway. Can't fight progress.
For sure, digital does on do well outside of ideal conditions. There are a few women in the plant who's voices are above 1/2 of the sample frequency so their calls come across as 100% aliasing after it gets compressed and encoded.
I think digital was chosen for us because they can have dozens of virtual channels on one frequency where as on analog they were paying for a licence transmit on several.
If I had to guess, they're using frequency hopping across your frequencies. Afaik, many emergency and LE services use a combination of encrypted and unencrypted radio comms, so you're probably only hearing the unencrypted comms as they hop into your frequency.
I doubt it's related to the backdoor references in the article. But it's been a while since I played around with RF and even when I did, I wasn't really an expert despite it being in the job description.
Just out of curiosity, when you say you "regularly pick them up", is it intelligible audio (clear voice conversations) or is it the digital modulation that's leaking over to your freqs? I don't have a good answer for the first problem since that shouldn't be possible unless there's an open patch somewhere that shouldn't be enabled, but I can 100% believe the second problem. In either case, it's poor practice from the radio maintainer of the offending system... and it's illegal regardless since their license is not valid for out-of-band transmissions and the modulation format is probably not licensed for use on those freqs. You'd be surprised, but FCC enforcement will take that very seriously.