Hi all, Jacob here.
I know I'm not here too often (I promise to change that,) but as a licensed amateur radio operator and a siren enthusiast for over ten years, I feel that this needs to be addressed. (Mods: if there is a post of this sort that already exists, or feel that this post doesn't belong on the board, please let me know.)
Many of us are excited when we head out with our gear and radios to go out and film a siren test. Many systems across the country use two-tone activation, DTMF, digital modes such as PSK31, FSK and so on. The flaw in this is that people can receive these tones over a scanner and replicate them to trigger the system.
It's easier than EM directors think when they're setting up the system in their municipality for someone to activate the system with malicious intent; but there are ways that it can also be prevented.
The recent situations in DeSoto and Lancaster, Texas, along with what seems to be a myriad of other false activations, or "hacktivations," are prime examples of this. Here are some thoughts that I've put down on paper over the past couple of years on this topic. Since this has come to be a fairly popular topic for discussion on the Facebook page, this should help clarify what could be done.
I am aware that Lancaster and DeSoto have taken their systems offline indefinitely due to the false activations, which I find rather outrageous, but it is after all their decision. I think that it is a tragedy that these activations have led EM directors to this point.
As a licensed amateur radio operator, I know that there are a few ways to make activation protocol more secure. This may sound like gibberish to most, but someone may find this useful. Both of these would require the EM office to make significant changes to their radio equipment (which I know would be out of the question.)
First and most importantly, some systems have their frequencies listed on sites like Radio Reference - which is where I believe the individuals who caused a majority of these activations retrieved their information. I personally feel that this information should not be available for public access for this exact reason. Frequencies for the system in Dallas County are listed on RadioReference - which is where DeSoto and Lancaster reside.
The sub-audible tone/ CTCSS tone (Continuous Tone-Coded Squelch System) on an FM transmission's carrier acts as a password of sorts. If this tone is not present on a transmitted carrier, the receiver will ignore it. CTCSS is used on repeaters across the nation to avoid harmful interference, and lets the repeater act as if it is in "closed channel" operation. This could be applied to warning siren systems also; think about it this way - If a system's receivers have a carrier squelch tone set to only accept that carrier of the transmitter, this would likely assist in keeping malicious activations to a minimum. I also feel that this would be the most effective method.
Operate on a higher frequency. Most, if not all systems in the US are now radio controlled, and operate in the VHF Business band (155MHz) or UHF Commercial band (470MHz.) Many scanners can receive in this range, and it is easy to find a transmitter and antenna to fit this bill. Business band transceivers are readily available for purchase to anyone - this is something that we simply can't help. However, it is more difficult for someone to find a scanner or transceiver that operates in the 1.2GHz range. I am aware that it would save money to operate on the 155/470 bands, but this would be another way to prevent malicious activations.
The FCC has recently taken action on this as well, however they are looking at man-made harmful interference as a whole. The FCC has issued a ban on the sale of transceivers that are not Part 90 certified. Part 90 of the FCC rules states that any transceiver cannot transmit outside of the allocated US Band Plan from the factory; which many of the Baofeng radios can do out of the box. The Baofeng UV5R and UV5R v2+ are prime examples; they can transmit on any frequency on which they can receive (136-174MHz and 400-520MHz.) It is possible to even transmit in the NOAA VHF Broadcast band, and send out false warning messages. These radios may seem harmless, but coupled with a high-gain antenna at a high altitude, the damage that these radios can do is catastrophic.
My point in this is folks, let's be very careful with what we do. It is fantastic if you want to include activation tones in your videos, in fact I am not against it.
However, do not show your scanner in the video or include the frequency on which the system operates in the video description. It is important that you keep that information to yourself if you happen to find it.
Please, please, please be sure to be careful with what you know.
Thanks for taking the time to read, I hope this helps in clarifying a few things.
Cheers!