@ret @farewell_ladmin well, with #TETRA, the advantage is that it's basically #ETSI trying to make a "secure" #GSM fork and thus TETRA Radios constantly transmit pings like a GSM phone.
- Espechally the vehicle- and on-persin worn radios as they also act as safety devices, sending distress beacon signals when flipped over (which is why it's explicitly being instructed to always put the radios on a desk in an upright/vertical position and never lay them down when switched on!)…
They are intended to allow personnel to discreetly call for backup and/or be found if they go radio silent or seem incapacitated. They don't transmit vitals but I think we all can agree that a patrol presumably laying on the ground whilst on duty is a clear enough sign for dispatch to send an ambulance and reinforcements.
- Don't ask me how I know…
So yeah, one can to an extend detect them and it's propably a matter of building some #NeuralNet and train it with passing-by data as well as integrating that with #GNUradio.
- OFC the results will be best in open countryside at a vantage point than at strert level in a big city.
And whilst it may warn against a regular patrol car, it won't help against #SWAT-esque units like #GSG9 that operate basically exclusively in #DMO mode aka. "direct #PTT" use without registering into a TETRA network, so instead they only get their signal "digipeated" (at most) by local TETRA cells based off the upload frequency and thus only can be located when they transmit.
- Plus they tend to sometimes use civilian / commercially rented transports for a more stealthy approach, putting an entire platoon on a "boxtruck" van...
