Quick Look

Investigating Radar Design Options for Preventing Inadvertent Deployment of an Instantaneous Personal Protection System, 10-9156

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Principal Investigators
Thomas J. Warnagiris
Michael D. Ladika

Inclusive Dates:  08/26/99 - 12/26/99

Background - The Instantaneous Personal Protection System (IPPS) is a system that detects a bullet and deploys a countermeasure (shield) to stop the bullet before it reaches its intended target. The objective of this project was to configure existing hardware on hand into a working prototype Doppler radar suitable for triggering an IPPS. This effort was necessary to confirm to interested organizations that the Institute has a viable radar design and is technically able to produce the required radar. The IPPS Doppler radar has many stringent requirements. Key among them is the ability to specifically identify the Doppler return only from a true ballistic threat (i.e., fired round). Fortunately, the characteristics of the Doppler signal from a small caliber round are distinctive. The most prominent features are:

  • A tone within a fairly narrow frequency range established by the velocity of the round

  • Increasing signal strength as the round approaches the radar

  • A single tone with frequency slowly decreasing as it approaches the radar (due to ballistic speed loss)

  • A lower frequency "fluttering" signal (i.e., much less than the Doppler frequency) imposed on the Doppler signal created by peak and null points in radar energy along the ballistic flight path.

 With the use of high-speed digital signal processing (DSP), it may be possible to produce an initiator-firing signal having an extremely low false triggering rate (inadvertent deployment). An immediate alternative to the DSP circuit is a hard-wired recognition circuit designed using off-the-shelf integrated circuits.

Approach - This quick-look project investigated, assembled, and evaluated a radar to demonstrate circuits for minimizing the inadvertent deployment of an IPPS. The primary objective of this project was to design, build, and demonstrate operation of a circuit that would discriminate between a moving bullet or a spurious radio-frequency signal from another source. A secondary objective of this project was to provide supporting technical information for the proposed design of a preproduction radar configuration.

Accomplishments - On November 11, 1999, the demonstration radar was integrated with the countermeasure material produced by Second Chance Inc. and the deployment system produced by Pacific Scientific Inc. This demonstration marked the first time that improved versions of all three IPPS components were assembled. Three tests were performed prior to the successful public demonstration on November 17, 1999. In all cases, the system intercepted the bullet well within the expected time limit. The radar was in operation for several hours at the open range during which no inadvertent signals were observed, even with two-way radios, cellular telephones, and overhead flights by 10-GHz radar-equipped F-16 aircraft.

The demonstration IPPS radar as configured for range tests (drinking cup included for scale)

Electronic Systems and Instrumentation Program
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