Raven Gunshot Detection Technology

The Champaign Police Department has contracted with Flock Group, Inc. to install Raven gunshot detection technology for use in select areas of the community on a trial basis. In total, 33 units were installed in Champaign in the Winter of 2022. The initial authorization for gunshot detection units is for a period of one year, through February 2024.

The below resources, including FAQ and policy documents, are provided to give residents a greater awareness of gunshot detection functions and limitations and CPD’s guidelines around use, privacy, and data storage.

Gunshot Detection: How the Technology Works

Graphic depicting gunshot detection process

Click here to learn more about how gunshot detection works

Gunshot detection units capture short audio clips of their surroundings, interpret that audio to detect specific sound patterns, and, ultimately, alert an officer when the system has captured the sound of a potential gunshot. The automated process of capture, analysis, and comparison typically takes seconds, and officers are alerted to the vicinity of the gunshots.

The process of gunshot detection works like this:

1. Each Gunshot Detection unit is equipped with a microphone that gathers audio for five seconds at a time.

2. The unit processes the audio to determine if a gun has been fired.

3. Audio suspected to be gunfire is uploaded to Flock Group, Inc. processing systems. These systems reprocess the audio to ensure that the sound was a gunshot and not a similar sound like fireworks or a car backfiring.

4. If the sound is determined to be gunfire, the unit sends an initial detection alert to Champaign Police Officers.

5. Simultaneously, the system cross-references detections from other nearby gunshot detection units. Using calculations based upon the time delays between units hearing the sound, the system is able to determine the approximate location of the incident. The vendor asserts that this automated process determines the location with a 90% accuracy to within 90 feet.

6. As the cross reference is completed, an updated alert is relayed to Champaign Police with a narrowed geographical location, and available officers are immediately dispatched to the specified location to investigate.

Frequently Asked Questions 

The Champaign Police Department has been authorized to install 33 gunshot detection units.

Installation is being completed in an area bounded by Bloomington Road to the north, Mattis Avenue on the west, Bradley Avenue on the south, and Prospect Avenue on the east.

The recommendation of where to deploy gunshot detection units was developed by the Police Department in consultation with a Flock Group, Inc. representative and based upon the analysis of five years of data on shooting incidents and associated locations.  The recommendation was based on providing adequate coverage of the neighborhoods most frequently affected by gun violence.

Gunshot detection units are similar to a Google Home or Alexa device, but instead of listening for “Alexa!” they listen for the sound of gunfire.  After a shot is heard, the devices use the sound as a cue to actively listen for additional shots and send an alert to police. Only the distinct sound of a gunshot can trigger an alert, and the systems are even designed to eliminate similar sounds, such as a car backfire or fireworks.

CPD Policy and Procedure 41.20. The Champaign Police Department created Policy 41.20, which dictates the use and documentation of gunshot detections by this technology.

Policy and Reports

  • December 2021 Council Bill: A Resolution Authorizing the Purchase and Installation of Automated License Plate Readers, Gunshot Detection, and Related Equipment from Flock Group, Inc.