Smart smoke detectors keep an ear out in vacant homes

Fires that start in vacant properties like this house are a problem for the city of Louisville. They often start in the middle of the night when neighbors are asleep. By the time someone notices the fire, it's grown so large that there's a risk it will spread to neighboring homes.

In 2015, the city of Louisville's Office of Performance Improvement & Innovation turned to civic hackers to solve the problem of vacant property fires. This led to the creation of the Completely Autonomous Solar-Powered Event Responder, aka CASPER -- a wireless device you put in vacant homes that listens for the sound of smoke detectors going off and sends text messages to let the city know there could be a fire.

The device contains a microphone, a 3G cell modem and a solar panel and battery.

One of the biggest challenges with CASPER is finding the best spot to mount it so it has consistent sunlight to charge the solar panel that keeps it operating.

The microphone in the CASPER listens for the sound of a smoke detector, which emits a unique frequency that CASPER is designed to identify. If the mic hears a smoke detector, it sends that information to the cloud which, in turn, sends out a text notification to designated people to let them know that there could be a fire in a home.

CASPER sends text message alerts if it hears a smoke detector.

Each CASPER costs about $150 to make, and plus a $10-a-month charge for the data plan for the cell modem.

This is one of eight abandoned, city-owned houses in Louisville that has a CASPER as part of a pilot program to test the system.

The CASPER hasn't made any false alarms during testing. There was one close call -- a smoke detector that was in one of the test houses had a dying battery, which made the detector emit a sound that the CASPER picked up.

The pilot program runs through March. Then the city will decide how well CASPER works and if it's worthwhile to extend the program to more houses.

Nathan Armentrout, one of the creators of the CASPER, said he'd like to keep developing CASPER to listen for other sounds such as broken glass or animal noises so the system will send notifications to the appropriate city department.