For most of a century, the fastest and most dependable way to report a fire in an American city was to break a small pane of glass, pull a hook, and walk away without saying a word. The street fire alarm box sent a number, the number was the location, [...]

Emergency plans usually treat the communications system as the instrument you use to manage the disaster, which holds up until the disaster lands on top of the instrument. Hurricane Katrina is the American reference case for that condition, with flooded central offices, generators that were... [...]

Public warning is one of the few things a local agency does where a single keystroke reaches everyone at once and cannot be taken back. The incidents worth studying are the ones where somebody investigated afterward and published what they found, because those records point at the same small set... [...]

Part one of this pair explained that a PL tone, a DPL code and a digital system protect nothing about who can hear you, and this part takes up the other half of the problem, which is who else is on the channel and what you are entitled to do [...]

A great many radio users, and a fair number of the supervisors who set policy for them, believe that a PL tone, a DPL code or a move to a digital system keeps outsiders from hearing their traffic. None of those three things does that, and none of them was [...]

On January 1, 2013, every Part 90 land mobile licensee operating between 150 and 174 MHz and between 421 and 512 MHz had to be running 12.5 kHz channels or equivalent efficiency. The rule was written as a spectrum housekeeping measure and it read like one, three lines about bandwidth [...]

Project 25 is usually explained to new radio people as a digital voice format, which undersells it badly. It began around 1989 as a procurement defense, written by public safety users who had watched the first generation of trunked radio lock them into single vendors and who could see digital... [...]

On February 16, 1968, a call placed inside the Haleyville, Alabama city hall was answered on a red telephone at the police station a few blocks away, and that is the event generally recognized as the first 911 call in the United States. Almost six decades later a large share [...]

The 470 to 512 MHz band carries police, fire and EMS radio systems in a small number of the country's largest metropolitan areas, and for nearly nine years federal law required those agencies to leave it. Congress repealed that requirement in December 2020, by which time the FCC had frozen [...]

Encryption on a P25 or DMR system is applied one transmission at a time by the radio that is talking, which means a talkgroup is only as secure as its worst-programmed portable. When a single radio goes out in the clear, the audio sounds exactly the same to everyone else [...]