Mission Statement - De-Spinning the Pro-Taser Propaganda

Yeah right, 'Excited Delirium' my ass...

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The primary purpose of this blog is to provide an outlet for my observations and analysis about tasers, taser "associated" deaths, and the behaviour exhibited by the management, employees and minions of Taser International. In general, everything is linked back to external sources, often via previous posts on the same topic, so that readers can fact-check to their heart's content. This blog was started in late-2007 when Canadians were enraged by the taser death of Robert Dziekanski and four others in a short three month period. The cocky attitude exhibited by the Taser International spokespuppet, and his preposterous proposal that Mr. Dziekanski coincidentally died of "excited delirium" at the time of his taser-death, led me to choose the blog name I did and provides my motivation. I have zero financial ties to this issue.

Saturday, May 17, 2008

Guesstimated Spectrograms

In a post at the beginning of 2008 [LINK], I had examined the significant differences between the waveforms from the older (1999) M26 "Advanced" taser, and from the newer (2003) X26 taser.

At the time I used the expression Holy Sh_t! because it seemed obvious to me that the long and low monophasic (DC) pulse from the X26 during the 'stimulation' phase was a smoking gun. Everything that Taser had claimed was safe about the M26 (short pulses, high frequency), was the opposite for the newer X26 (continuous 100% duty cycle, low frequency). [LINK]

A spectrogram is a plot of frequency components over time. [WIKI] The two following spectrograms (below) are guesstimated based on the Taser specification sheet, and my moderate experience in this field.

[If Taser disagrees with the approximate accuracy of these two plots, then they are perfectly free to e-mail me the actual M26 and X26 spectrogram plots. My e-mail address is in the right hand column.]

What is obvious here is that the X26 waveform is primarily low frequency at the pulse repetition frequency of 19 Hz. Thus, the duration of the 19 Hz is the full five second cycle and is continuous 100% duty cycle during that period. This is massively different than the older M26 which used a damped sine wave at 50 kHz, and (due to the symmetry of the pulse) kept the generation of low frequency components at the pulse repetition frequency of 15 to 20 Hz extremely low.

Taser waveform is very short pulses? M26 yes, X26 effectively no.

An everyday example to help you grasp the point is the following: Some audio amplifiers use a digital technique to achieve very high efficiency. Instead of amplifying the audio signal in the analog domain, they use a high frequency stream of narrow digital pulses. The number, width or positioning of those pulses is modulated in proportion with the audio signal. The actual output from the final gain stage is simply a series of those inaudible high frequency digital pulses. But that same waveform actually contains (actually is) the amplified audio. You can connect a speaker and listen to it. The designers might include a low pass filter to remove the high frequency components to meet RF emission standards. But the point remains the same, high frequency pulses (if asymmetric in amplitude about zero volts) can be used generate a low frequency signal. And that low frequency signal is perfectly real.

Given that Taser continues to maintain, even post 2003, that 'the taser' uses short pulses and is therefore 'safe', indicates that they might have overlooked the implications of using a monophasic DC pulse. They did realize that the fundamental frequency is 19 Hz, but even now they don't seem to acknowledge the next logical conclusion - that the 19 Hz component from the X26 is not a short, hundred and something microsecond pulse.

The X26 waveform is five seconds of 19 Hz.

It really is.

Even the expert Reilly didn't seem to acknowledge this point. [LINK]

I bet that if someone at the Braidwood Inquiry asked him about this detail, and gave him time to think it over, he would realize that he missed it first time around. It would be very interesting to see if he was willing to change his tune with respect to the duration of the X26 waveform.



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