Police and fire scanner
Lafayette and Tippecanoe County dispatch moved to digital trunked radio, which put it out of reach of a hobby scanner. This is the same thing rebuilt in software.
- Radio
- One HackRF, parked at 855.4 MHz. It never retunes.
- Capture
- 12 MS/s. Both trunks come out of the one stream.
- Systems
- Tippecanoe County and Indiana SAFE-T, four control channels between 851 and 860 MHz
- Transcription
- Whisper large-v3-turbo, int8, on a GTX 1050 Ti
- Priority
- P1 purple, P2 red, P3 yellow, P4 blue
Right now
Sorted the way the phone app sorts: worst first, then by how live it is.
listening…
How it works
A trunked system assigns a different voice channel to every call, so following one normally means tracking the control channel and retuning constantly. Both local systems fall inside a single 12 MS/s capture, so the radio sits still and OP25 demodulates them as two independent channels out of the same stream.
Transcript lines are numbered, and the summarizer has to name the lines it used for each incident. Every incident on the map links back to the transmissions and audio clips behind it. An incident's timestamp is its newest transmission, not the moment the summary ran.
Settings that matter
Voice-activity detection is off. Dispatch traffic is clipped and often under a second, and the detector classifies a two-word reply as not speech.
Whisper runs as the turbo model quantized to int8, because the full model loads 1.6 GB of weights onto a 4 GB card and then runs out of memory mid-decode. Local street and place names are passed in as a prompt; without them the model invents Indiana-sounding roads that do not exist.