The problem is that the unfiltered output of this device contains a wide range of spurs and harmonics which will radiate right across the VHF and UHF bands.
Plus the antenna (a few feet of wire) will have multiple resonances across the same range.
It will radiate hundreds of signals, and the odds of them interfering with a nearby essential service will be very high. And note that the essential service receiver is capable of hearing signals in the micro-watt range and is routinely trying to receive them.
Many years ago the record was "1000 miles per milliwatt" using CW.
No need for "certain atmospheric conditions".
The point was that very low power signals can go a long, long way.
> And even a few micro-watts is sufficient to communicate across town.
> Many years ago the record was "1000 miles per milliwatt" using CW.
Even a tiny signal can be enough to block the operation of a nearby police repeater (which is also trying to hear weak signals).
Modern protocols like 5G New Radio that have better propogation at the fringes of connectivity would serve life critical applications with improved coverage and significantly more intelligible voice quality than what the current public safety networks are capable of doing.
If you look at the telephone/power poles in your neighborhood you will see a device with two antennas hooked into power every few blocks. This is a recieve only amplifier that has to be used to amplify these weak signals from handheld public safety radios that use protocols like TDMA with poor interference resistance and no error correction.
If the wanted signal is very weak (eg from a distant aircraft using VHF AM), and there is an interfering signal on the same channel, the emergency communications will be distrupted.
Pivoting topics is a bad faith conversational tactic FYI, and doesn't follow HN's guidelines. I encourage you to fully read the guidelines linked at the bottom of the page.
TDMA amplifiers could well be a problem in your country, but the whole point of the discussion is that transmitting a wide band of RF hash will certainly be detrimental to thousands of other radio users, whether or not they are using a TDMA public network.
Aviation needs to modernize, I have zero sympathy for the aviation community getting constant hallpasses on ancient altimeters that lack filters to reject RF from nearby frequencies, leaded avgas, and abysmal working conditions for those stuck in the industry.
The FAA dragging their feet in the USA trying to act like they should never have to test how interference affects hardware on planes is insane, they waited till well past when 3.5Ghz went into cellular use to make any effort to performance test altimeters for band conformance. The FCC's timelines are long, the FAA had at least half a decade heads up of when the 3.5Ghz auction would occur, and additional time after the auction before Verizon and AT&T put the spectrum into service.
We have waited 25 years past when everyone else stopped using leaded gas to get rid of leaded Avgas[1].
As a Seattleite who grew up with families made up of Boeing Engineers, the problem of vulnerable radio transmissions from aircraft could be resolved with a network of reception sites just like Gogo uses at a much higher frequency allocation. This problem is just not a priority for the Aviation community, they would rather not invest in better equipment and infrastructure.
1 - https://qz.com/leaded-aviation-fuel-is-prompting-bipartisan-...
Edit: Trunked, not Truned
Unlike FM it doesn't suffer from the "Capture Effect" so you can tell if a weaker signal is trying to get through on a busy channel. And unlike FM it doesn't suffer from the Threshold Effect where weak signals suddenly disappear into the noise.
And of course Digital modulation is ruled out by both of the above considerations.
The only mode which is more efficient (for weak signal communications) is Single Sideband, and that can't be used in aircraft due to Doppler shift.
It is true that local reception sites can help, but they are not possible over water. Perhaps one day satellite systems might finally replace aircraft AM. The problem at present is the cost for fitting to light aircraft.
It would require higher complexity, with no improvement for marginal signals.
One possible improvement would be "Synchronous AM" (eg 1/2 of a QAM signal) but that will also lose phase lock in weak signal conditions, eg when it is most needed.
This, in conjunction with whoever owns the plot of land the offending device happens to live on, determines who is to blame when someone is broadcasting illegally.
Here's a link describing the activity, in case you're interested: https://hamradioplanet.com/what-is-a-fox-hunt-in-ham-radio/
Steal The Air!! -Pump Up The Volume