Monday, December 22, 2014

Gun shots: Part IV

"Gimmee all your money!"
The victim, Mark Curby, picked a bad part of town to walk through.  In this business, it is very important to pick models with a great set of legs.  Microphone is in left pocket of shooter's hoody
Test shot six.  "Mark Curby" centered in front of garage.  First major echo 10ms from first pressure rise.
First six milliseconds shows several peaks that saturate mike.  Very busy chart.
All of those clipped waves look like square waves.  Square corners produce lots of bogus, high frequency content when mapped into the frequency domain.

From Wikipedia

Also from Wikipedia
Looking at the high frequency content of the signal may  be the most robust way of identifying signals that saturated the mike's response.  "Robust" in this context means being able to identify a gunshot (saturation) without first "blueprinting" the mike's performance characteristics.
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2 comments:

  1. Old NFODecember 22, 2014 at 5:22 PM

    Looks like some kind of AGC circuitry is kicking in and dumping the dB back to -30, unless I'm reading it wrong. Are you running Raven?

    ReplyDelete
  2. Eaton Rapids JoeDecember 22, 2014 at 7:11 PM

    I am recording using Raven.

    I do not plan on doing any more close range sound recording. I cannot be doing my equipment any good.

    I do plan on messing round with sound abatement and recording from approx 50 feet. I heard a rumor that there are people living in densely populated counties near the east coast who like to shoot and their gun ranges are harassed with nuisance-noise litigation. Not everybody is blessed to live in Eaton Rapids Township http://www.michigantownships.org/twp_details.asp?fips=24560

    Best regards,

    -Joe

    ReplyDelete

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