Everyone knows that listening to the police scanner is legal.* Less well known: every time a radio transmits, encrypted or not, it broadcasts its location to anyone who is listening properly. We know governments use this technique extensively (protip: don't use a satphone in a warzone). In the year 2038, this power devolves to the people. This is a practical introduction, with released code, of a system for publishing realtime multilateration fixes on a map, for a live public safety radio system.Stingray is so 2018. *(in the US, your mileage (kilometerage?) will vary in other countries)