U.S. flag

An official website of the United States government, Department of Justice.

Unobtrusive Suicide Warning System, Final Technical Report

NCJ Number
Date Published
October 2011
151 pages
This final report presents the findings of a study that examined an unobtrusive suicide warning system for use in correctional institutions.
This report presents the findings of phase II of a three phase project to develop an unobtrusive suicide warning system for use in correctional institutions. The suicide warning system is designed to measure an inmate's heart rate, breathing, and general body motions without being attached to the inmate's body. The system uses a modified commercialized range controlled radar that is used as a motion detector for home security systems. Phase I of the research was completed in March 2009. The results of phase II, completed in December 2010, are presented in this report and include the following: 1) improvement of the state estimation algorithms by inclusion of the continuous wavelet transform and stationary wavelet transform, leading to an overall diagnostic accuracy of 83 percent for motion, still, and concern states; 2) improvements to rate algorithms for use in rate estimation leading to 15 percent accuracy while retaining about 50 percent of all estimates; 3) improvements to alarming algorithms that alert when the subject is in a concern state - use with test subjects led to a false alarm rate of less than 6 percent; and 4) development of a near-real time implementation of the system. The report also presents information on the final phase of the project which is to design a hardened system for long-term use in an operational setting. Tables, figures, references, and appendixes

Date Published: October 1, 2011