We talked about this years ago

Now apparently the technology to use sound sensor arrays to locate a source in urban environments is being deployed.

I do not for a moment believe that its main impetus is the desire to save lives however.

Notice the tricky little dance in the text, whereby they point to the high rate of gun ownership in Texas as a reason why a city needs a sonic surveillance network to locate gun shots. This kind of lie (we call it “fake news” now, but it’s just a form of lie – we could call it “the subtle art of the lie”) will always sway a few people and so it will continue to be used.

In reality of course, the city and state governments which commit the most significant infringements against the right to bear arms will tend to have the higher rates of violent crime in those areas as a result. They know this, and yet call for more of the cause, presenting it to us as the cure.


17 thoughts on “We talked about this years ago

  1. FWIW, ShotSpotter was deployed in East Palo Alto years ago. It also made a fictional appearance in the TV show “Person of Interest”. Don’t know why this paper thinks its something so novel.

  2. Every “Obama-phone” has a sound sensor, GPS and sufficient computational power to link with nearby phones and calculate sources of “gun shots”. They are being carried by the demographic most likely to perpetrate gun violence.

    Just sayin’….its all in place and paid for. The phone does not belong to the person carrying it. It belongs to the guberment.


    • “Every “Obama-phone” has a sound sensor, GPS and sufficient computational power to link with nearby phones and calculate sources of “gun shots”.”

      I very much doubt that.

      • Why do you doubt it? To me it seems perfectly straightforward. The one thing I would doubt is that the government would limit applying this to government issue phones, and/or only to cases where it has a warrant in hand.

        • Simply detecting a loud transient is simple and straight forward. The technology we’re discussing, which pinpoints the source location of said transients, requires an array, with known spacing of detectors to within inches. Those detectors must be time sync’d to a resolution on the order of a millisecond. The system also must be able to deal with the potentially VERY confusing issue of reflected sounds in an environment replete with reflective surfaces, and also distinguish supersonic crack from muzzle blast and impact sounds. We’re talking highly sophisticated processing.

          Relying on hacking into people’s phones, stuffed in pockets and purses, which are constantly on the move…that’s a terrible way to do it. COULD it be done? Maybe, maybe not. I doubt it would be considered worth the effort, even if it were possible.

          Could you simply record the sounds and get a general idea of the location to within a block or two? Sure, but that’s not what we’re talking about. People in the general area can do that just as well or better than relying on a system that monitors phones.

          Anyway, the over-arching issue is that actually saving lives would be far easier and guaranteed. Just respect the constitution, and stop with the Critical Theory and other forms of victimology being taught in all of the public schools and universities.

          • The timing is easy with the GPS receiver available in the phone. They have accuracy well under a microsecond available to the phone processor. The direction detection without knowing exact position, combined with reflection in a urban environment, is what kills it.

          • Also; I worked for years in a downtown building on an a busy intersection. I was surprized at the number of “backfires” (actually, unburnt fuel lighting off in the tailpipe) which sounded freakishly like gunshots. Again then; highly sophisticated descrimination software would be needed to reduce the number of false positives.

            Point is; we’re talking about a very sophisticated, fixed array of detectors, all interfaced with one another at some point, so as to create what might be described as a 3D holographic image of every aspect of the sonic “event”.

            Bats do this with their sonar and only two ears, to “see” their environment to a resolution that allows them to catch flying insects, and so it’s entirely possible. On the other hand, I actually witnessed a bat, in flight, crash hard into one of my vertical antennas at my house one fine evening…

      • What part do you doubt? That every phone has a microphone? That every cell phone sold in the last five years has GPS or that every phone has sufficient CPU and registers to perform Fast Fourier Transforms?

        • It’s the required, precise location that’s the main problem, as Joe pointed out. It has to be well inside the wavelengths being analyzed. I figure an error of inches would blow the whole program. GPS wouldn’t work on that scale. Also, again, the phone being in a purse or other such would be a problem, as would the A/D conversion rates being different for different phones, etc., etc., etc. and if the various phones move relative to one another during the event, there’d be additional errors for which to account. The problem would compound exponentially with each variable.

          And again and again; if saving lives were the objective, then attempting to solve such a monumental problem as pinpointing the location of a sound source by using a gaggle of randomly placed, randomly moving telephones as what would best be described as a “phased array” would be way, WAY down the list, and so saving lives is obviously not the objective.

          So they’re full of shit right there.

          Mathematically speaking then, full-of-shit over pipe dream equals some degree of full-of-shit any way you look at it, and therefore the technical matters, whether or not they’d actually be solvable, are moot.

          Probably the best take-away from the story is in seeing the lengths to which the authoritarians (the criminal class) are willing go, using other people’s money, for more control, and how the age-old selling point (lie) for the purpose of entrapment (that it’ll make us more secure at some undetermined point in the future) is still as viable as ever in spite of millennia of evidence.

          • I don’t see what wavelengths have to do with it. This is basically the same problem as GPS itself (with the directions reversed): you have arrival times for a given signal at several receivers at known positions. The unknown is x,y,z of the source. You need four receivers, because the other unknown is t, the signal transmission time (again, just as with GPS). A position error of a receiver gives you, to first approximation, that same position error in the answer.
            The other component is determining the arrival time of the signal. Given signal distortion, that may be off. If you misjudge the leading edge of the sound pulse by a millisecond, your position is off by a foot.
            This isn’t a phased array system (a beam forming system). If you try to analyze it that way you’ll indeed conclude that you need a great deal of precision. But just like GPS, it’s simply a time of flight system, and that much easier.

          • Reflections mess everything up. With a building between the receiver and the source the dominate path may be off a tall building down the block.

          • Certainly, multi path propagation makes it harder. One option is to use the earliest pulse and assume it’s the direct path. That often helps, not always. A second option is to rely on redundancy. The minimum 4 sensors is only reliable if none is picking up a reflected signal. If you have significantly more sensors, you can filter out the ones that contribute wrong data, so long as there aren’t too many of them.

  3. IIRC, Redwood City (next door to E-PA) also had that system installed. They gave up on it. Lots of money spent, and no useful results have ever been found. One of the major problems was the response time of police. Not a practical system for most areas, as they have to be on site in under a minute. Well under a minute, in most cases. If the BG is walking around with a long gun, it might help. Maybe. Handguns? Not really.

    IIRC, firecrackers cause problems for the system. That’s a near constant background here in CA. Asians fire them off all the time, it seems.

  4. I heard about them putting this (I believe it was even Sound Spotter) into certain neighborhoods in Chicago years ago already. The earliest news article I could find was 2012 but I think I remember having a conversation about something like this in Chicago even earlier than that, in the late Bush administration years. This may be new-ish in some areas, and maybe it’s more integrated now, but in many ways it’s old news.

    • I found an article from 2008, which mentions that such systems have been in place in some cities since as early as 2004.

      Another source suggests that they abandoned it in 2007 due to cost and lack of effectiveness. Apparently it’s back.

      • For government programs, cost and lack of effectiveness are features, not bugs. They are used to justify spending more money.

  5. This system, or an earlier version thereof, has been deployed, failed and uninstalled in cities across the nation over the past decade. Their (the company sourcing the article, specifically) failure to mention that fact reveals their intent to deceive.

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