Testing, Forensic Examination, Prototype Evaluation of Conducted Energy Weapons

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A Simple Field Test Procedure for

Stun Guns

Rassettica Testing Limited May 2016

Authors: Andy Adler, PhD, PEng

Dave Dawson, PEng

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Contents General purpose of field testing ................................................................................................................... 3

Specific purpose ............................................................................................................................................ 3

Qualification and training of Personnel ........................................................................................................ 4

Equipment needed ........................................................................................................................................ 5

Two stages of testing: acquisition and analysis ............................................................................................ 6

Data handling ................................................................................................................................................ 7

Presentation of Results ................................................................................................................................. 8

Appendix A: stun guns ............................................................................................................................... 10

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General purpose of field testing

Field tests are experiments, research or trials conducted under actual use conditions rather than in

controlled conditions in a laboratory. (business dictionary.com) Field testing offers advantages of cost,

timeliness and speed compared to laboratory testing. Quality control (QC) of raw data files and test

results is an important an objective in field testing as in laboratory testing. Specific attention must be

given to those factors which are germane to data integrity, such as operator education, detailed test

procedures and data handling.

Specific purpose

This test procedure is written to describe the methods, equipment and personnel used to develop a

relative characterization of the electrical charge characteristics of stun guns with particular emphasis on

charge (Q) delivered by the stun gun.

Stun guns are Conducted Energy Weapons which discharge pulsed electricity between two probes. The

pulsed electricity is generated by battery supplies in the guns. The battery supplies may be carbon-zinc

cells or rechargeable lithium ion cells. Battery voltages usually do not exceed 9 V DC.

The pulsed electrical emissions from stun guns do not cause neuromuscular incapacitation but they do

produce pain when the stun gun is in contact with the subject.

Stun guns are, for the most part, manufactured off-shore from the continental US. There are no publicly

available design specifications, patent documents or performance standards. From examination of

several dozen makes and models over a period of several years, it is apparent that the electrical

characteristics such as voltage, current, pulse length, pulse width, pulse repetition rate and charge are

highly variable from one manufacturer to another and from one model to another. There does not

appear to be any standard design criteria for these parameters. In addition, there is no scientific

investigation or reporting of the nature and effects of the emissions from stun guns. Performance

specifications and results from performance testing are not available. Mechanical characteristics are

very generalized as to size, case material, probe spacing.

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Electrical and mechanical characteristics may be generalized by:

Narrow pulse width, usually between 5 -10 µs

Pulse repetition rates between 1 kHz and 25 kHz

Separate arming and triggering controls

Frequently variable amplitudes, resulting in different charge per pulse characteristics

Much smaller Vmax or Vpeak values (under load) than package advertising would suggest.

Some typical stun guns are illustrated in Appendix A.

Qualification and training of Personnel

One tester is trained in the specific instrumentation and manual procedures used for signal acquisition.

The tester has coincident company responsibilities in Quality Control, Management and Chemical

Analysis. The responsibility of the tester is to maintain control of the stun guns, ensure their readiness

and during testing, to fire them into the resistive load. All file handling, naming and uploading tasks are

performed by the tester in accordance with instructions from the analysis engineers.

The analysis engineers have extensive backgrounds in testing, measurement and instrumentation. Dr.

Adler is a Canada Research Chair in Biomedical Engineering in the Department of Systems and Computer

Engineering at Carleton University in Ottawa, ON, Canada. Dave Dawson is the Senior Test Engineer for

Rassettica Testing Limited and a Research Associate for Dr. Adler. Further information on these people

may be found at http://www.sce.carleton.ca/faculty/adler/ and http://rassetti.ca/about/.

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Equipment needed This procedure does not depend on the specific make and model of test equipment. Rather what is

listed is indicative of the qualities and capabilities for this particular field test procedure

1. 600 Ω resistive test pad with conductive contacts. We used Ultra High Moleclular Weight

(UHMW) plastic on which to mount banana plugs connecting to the resistive load and contact

points for the stun gun.

2. 100x compensating voltage probe,

3. oscilloscope such as USB connected picoscope 4224 with 12 bit quantization, 20 MS/s sampling

speed and 32 MS buffer size

4. controlling laptop computer such as Dell I7 Vostro with proprietary software to control the

measuring instrument1

5. associated cables and connections

Figure 1: Picoscope 4424 Oscilloscope

1 Available free from https://www.picotech.com/

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Two stages of testing: acquisition and analysis Field testing of stun guns is done in two stages. First, the signal is acquired from the stun gun and

secondly, it is analysed for the key component of charge (Q).

1. During the signal acquisition, the stun gun is fired for up to 7 seconds into a resistive load (600

Ω) which approximates the resistance of a major body muscle.

2. The stun gun is usually energized by two switches.

3. The first switch, usually a slider switch, arms the circuitry and the second switch, usually a push

button switch just above the arming switch, triggers the electrical discharge.

4. The stun gun is held on the non-conductive pad so that the contacts touch the metal contacts

which transmit the electricity to the resistive load.

5. The measuring instrument (oscilloscope) is triggered to open a 7 second window of signal

acquisition.

6. The push button trigger is depressed so that approximately 5 seconds of discharge are captured

by the measuring instrument.

7. It will be noted that good contact with the contacts on the contact pad will not produce any or

very little arcing sound. An absence of audible sound and no visible arc means that all the

discharged energy is flowing to the resistive load for measurement and recording. This is the

desired result. Poor contact with the contact pad or discharge in open air will produce a loud

snapping sound and a visible arc. This is not a desirable result.

8. The measuring instrument ceases capturing signal (either automatically or manually).

9. After the measuring instrument has recorded an interval of signal capture, the raw data file is

saved with date/time stamp, make and model and serial number of the stun gun.

10. A second and third discharge from the stun gun is taken following the above steps.

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Figure 2: Block Diagram of signal acquisition A binary data file is created by the measurement equipment: this file is labelled with the name (model)

of the stun gun, date and time of test and serial number, if available. For example: 20160126-0001 s1005

unit2 test2.psdata. The raw data file is uploaded to DropBox and retrieved by engineers for analysis of

the key electrical characteristics. Raw data is preserved on a secure data server for future reference.

During signal analysis, the binary file is converted to a format compatible with Matlab. The custom

Matlab code generates tabular and graphic analyses of pulse time, pulse charge, pulse rate, current

(avg), and rate variability (COV). Much more information is available from the data file but for the

specific purposes of this field test, only the above noted parameters are presented and compared.

Data handling Raw data files are maintained on a secure server at Carleton University, Ottawa, Canada for a period of 5 years. Copies of the raw data are used in local working directories to prepare the analysis and presentation of results. Access to the raw data files is restricted to 2 people.

UHMW plastic pad with conductive contacts

600 ohm resistive load

Measuring instrument Stun gun

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Analysis of electrical data

The analysis of data from the firing of the stun gun into a fixed load is done by means of executing

custom Matlab code on the raw data files which are converted to Matlab format. Voltage peaks, pulse

widths, pulse shapes, pulse trains, and single waveshapes are identified and compared against each

other to identify and quantify variability.

Presentation of Results

Test results are prepared in report and tabular format according to specific instructions of fee-paying

clients who wish to understand the performance of individual stun guns. Results are not published, nor

peer-reviewed.

Table 1: Sample tabular presentation of some test results

Monster 18M 20160215-0001 Unit 1 Test1_2

Pulse Time (μs): 13.875

Pulse Charge (μC): 0.323

Pulse Rate (kHz): 5.851

Current avg (mA): 1.890

Rate variability (CoV): 0.001

Guard Dog Security 20160408-0001 unit 1 test 2_3

Pulse Time (μs): 35.700

Pulse Charge (μC): 1.105

Pulse Rate (kHz): 14.705

Current avg (mA): 16.249

Rate variability (CoV): 0.002

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Figure 3: Typical pulse train and individual waveshape of Ruger

20160321-0001 unit 2 test 1_1

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Appendix A: stun guns

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