Shotspotter CEO Answers Questions on Gunshot Detectors in Cities

https://www.aclu.org/blog/free-future/shotspotter-ceo-answers-questions-gunshot-detectors-cities

31 56 11 years ago

TruthSHIFT• 11 years ago

Does this technology have a slippery slope? Assuming that the technology isn't useful for recording conversations, what's the worst that could happen by implementing this in residential neighborhoods?

jagermo6• 11 years ago

As far as I see it you waste money that could be better used in staffing police, implementing social programs etc - this thing is a solution to a very tiny problem: gunshots that are not reported via emergency calls. As far as I can see this does not help with robberies, burglaries, attacks with fists/knives/bats etc.

Even if its not a slippery slope - I'd imagine there are several better alternatives where you can spend the money.

detaro• 11 years ago

this thing is a solution to a very tiny problem: gunshots that are not reported via emergency calls

I wondered how big a problem this is, but the only number I quickly could find is annoyingly from their advertising material and claims that in some areas only 10 % of shots were reported, which is not really the relevant number. Does anyone have a number on how many people die of gunshot injuries that either weren't reported or reported to late?

breischl2• 11 years ago

>this thing is a solution to a very tiny problem: gunshots that are not reported via emergency calls.

That's not exactly true. When people call in gunshots they frequently have at best a vague idea where the shots came from. If you're sitting in your house with the window open, the shots will most likely sound as if they came from that direction - even if they were actually in the opposite direction. So you could be sending the police to a place 6 blocks away, which in a dense urban environment is quite a long ways indeed.

Being able to reliably figure out the actual location has value.

source: we have lots of gunshots in our neighborhood. Police response and ability to actually catch people has gone up since the spotter was installed.

aorloff• 11 years ago

I'm not an expert, or even a layman in audio encoding, but it seems to me that a solution could be found that couples an open source capture program with their backend. The open source (audited and only updated from the open source branch) capture program filters the audio stream down to something that only contains a gunshot signature, and nothing else. If the motivation is there a solution is certainly possible.

toomuchtodo• 11 years ago

It could be done, similar to this lightning detection project:

http://www.lightningmaps.org/realtime

http://www.blitzortung.org/Webpages/index.php?lang=en&page=3

TL;DR They do triangulated time of flight for EM emissions from lightning strikes.

CHY8722• 11 years ago

Thing is, with lightning it is dead easy because you're talking about what is essentially a straight line through the atmosphere.

In a city, you get more issues: double datapoints from the gun and the bullet, multipath effects, etc etc etc.

joosters• 11 years ago

But as the article says, they need the original audio in order to improve the gunshot detection - for example, if a gunshot is reported elsewhere but the detector doesn't classify it, they can grab the audio from the record to train the detector and hopefully improve it.

If you never capture the raw audio, you won't be able to train the system to better detect the gunshots and to reduce false positives.

jagermo6• 11 years ago

Wait - what? There are so many guns fired in US cities that a company can build a sustainable business creating a system that spots these gunshots?

dntrkv2• 11 years ago

I've lived in Sacramento, Portland, and now San Francisco and I have yet to hear a gunshot in any of these cities.

jagermo6• 11 years ago

Right? I thought that was just something from TV/Movies - this looks more like they are selling fear than something real.

Why would a city invest in something like this? Especially if you get the information via emergency calls?

sehr• 11 years ago

I've lived in Oakland, LA, and SD and have heard shots in all of them.

Though to be fair it was New Years in San Diego, and Santee is a bit out of the way

batbomb• 11 years ago

I've heard gunshots in SF more than a few times. Several times in the mission, once in the tenderloin, and once was a half block away from my house in the Richmond. I walked over right as EMS got there and saw them trying to stabilize a neighbor in a pool of blood.

I also made the dumb mistake of tapping on a window sitting on my couch once when I saw a bunch of funny dudes with helmets just outside it. When they looked in the window I realized it was actually SWAT, right before they raided the house two doors down.

rmxt2• 11 years ago

I know that the amount of gun violence in the US is sometimes a shock to Europeans/foreigners in general, but I think a more pertinent question for most Americans is "Is the cost/benefit ratio worth it? Is this a proper allocation of public funds, or is it just another toy for local police departments to use?" My surprise in seeing that this is a sustainable business is this latter point: single-vendor sourced items and IDIQ contracts are a recipe for government spending disasters.

EDIT: My impression is that gun crime is heavily concentrated down to individual blocks or neighborhoods in urban areas. I don't like the idea of these devices in general, but I imagine that if they were deployed, they would be concentrated in so-called "high risk areas".

jagermo6• 11 years ago

I was more under the impression that the gun violence is not really so high as to justify a constant monitoring system to watch out for (especially if you need a person to look over the reports and then alert law enforcement - I get the feeling a emergency hotline can cover this as well).

This looks like it targets a very small (but probably high profile) subsection of criminal activities. For example, it wouldn't detect someone robbing/beating/stabbing someone.

dragonwriter2• 11 years ago

I think the business was actually built for the military (quickly locating where enemy fire is coming from is fairly high value there) and has since been marketed to civilian law enforcement.

At least one civilian agency which has adopted it seems to have found that its not worth the cost. [0]

[0] http://www.sfgate.com/crime/article/Oakland-cops-aim-to-scra...

jagermo6• 11 years ago

That makes sense. I've seen something similar on the TV show "Flashpoint", mobile microphones/sensors were used to triangulate the position of a sniper iirc. This obviously makes sense, if you have the manpower to react to something like this.

But yeah, it might look cool at first glance, but I don't think its worth its money.

skymt• 11 years ago

I just looked up the LAPD's crime statistics: http://assets.lapdonline.org/assets/pdf/cityprof.pdf (The NYPD's equivalent report doesn't count shots fired.)

Between April 5 and May 2 of this year, there were 187 recorded cases of shots fired in all of LA.

ceejayoz4• 11 years ago

With 92 shooting victims in that same time period, I'm guessing that's a massive undercount. Probably only counts times they catch and charge a shooter.

darkmighty• 11 years ago

I don't know how much they're charging, but in violent cities it sounds useful. You can have the exact location of a gunshot and dispatch an officer in a matter of seconds, and microphone arrays should be pretty cheap. Together with cell-id positioning it's a powerful tool for investigation: you can have the exact location/time of the shot and exactly who was nearby that that moment.

The alternative for violent areas is relying on witnesses to both dispatch help and confirm date and place of gunshots.

grecy3• 11 years ago

And insanely, they're interested in "detecting gunshots" rather than stopping them in the first place, by, you know, taking guns away.

I'm not from the US, so it was quite shocking to be a friends BBQ outside LA and hear multiple gunshots over the course of the night. They are quiet teachers, and have kids. They don't need gunshots in their lives.

hga6• 11 years ago

Yeah, well, trying to "[take] guns away" would trigger a civil war that would kill orders of magnitudes more people. That, in fact, is what sparked the American Revolution, when the British attempted to seize or destroy gunpowder, cannon, etc. (they did manage to damage 3 cannon).

If those people don't need gunshots in their lives, they should move to some place where they're not so common. Like the majority of the US where concealed carry is legal and, it is my impression, such bad areas are much more compressed.

151553• 11 years ago

taking guns away

Sorry, going to need an amendment to the Constitution of the United States of America for that.

And even after said amendment: good luck preventing people from acquiring and illegally owning firearms.

Inner-city gang wars aren't even remotely reason to infringe upon one of the most important American rights.

danans• 11 years ago

Not all US cities, and even then not all parts of those cities. In places with high poverty rates and gangs protecting their turf: yes. The gun violence rate is orders of magnitude higher there.

admax88q• 11 years ago

The privacy concerns with systems like these is not what they currently do, but what they are capable of.

It doesn't matter what your privacy policy says, and it doesn't matter if the default configuration is to only download the audio near the time of a possible gunshot.

The important part is that these devices can stream audio to remote servers. The NSA or anybody who finds or can coerce accesses to the system could use them to eavesdrop on everything within range.

No amount of "privacy policy" is going to prevent it.

wl• 11 years ago

That's assuming that audio from these sensors is at all useful for eavesdropping on people. Try a speakerphone lately? Even with higher quality codecs than we got in the POTS days and things like beamforming, the result is pretty terrible in decent sized conference rooms. Now try this outdoors, further away from people, with the noise floor of a city instead of a quiet room.

The cases people point to where ShotSpotter has picked up understandable words have been people very close to sensors who were shouting immediately before, during, or after gunfire the system picked up. But at that point, it's unreasonable to claim some sort of violation of privacy when people are screaming for all to hear.

Animats• 11 years ago

Redwood City, CA had the first system. It was much simpler than this. They had analog microphones on phone poles, connected to a logarithmic amplifier which traded dynamic range for bandwidth. Phone audio is 8 bits at 8KHz; think of this as remapping to 16 bits at 4Khz, although it was done with analog hardware. They needed the dynamic range to see the full risetime of a gunshot, and gave up a big chunk of the voice spectrum to get it.

Each microphone had a wired phone line connection to the central system at the police station, which was a PC with a data collection card running LabView. A LabView program turned gunshot information into map plots. It was a simple, local system.

The new systems are much fancier. They're "cloud-based", which means the data goes first to ShotSpotter's HQ. They have synchronized clocks (probably from GPS), so they can send in timed audio snippets to be matched at the analysis center. It's a service now, rather than just hardware. Not clear what kind of data connection they have; probably cellular data.

NoMoreNicksLeft2• 11 years ago

Is it possible to create a (cheap) non-firearm device that mimics gunshots closely enough to fool the system?

Would be fun to put dozens up all around, on slow timers.

hga6• 11 years ago

Depends on the sophistication of the system, and how many microphones it has. The vast majority, if not pretty much all of this class of gunshots, are going to start with the bullet being supersonic, the shock wave of which contributes to the signature (in the case of sniper fire I mentioned elsewhere in this discussion, it will tend to fool people into thinking the source is as much as 90 degrees from where the rifle actually is).

I'm having difficultly coming up with anything that isn't essentially a blank firing gun, and I'll note those are deadly really close up.

NoMoreNicksLeft2• 11 years ago

So, a firecracker won't do the trick? I realize that's still explosive, but unless you're stuffing them up a nostril first they're pretty safe.

151553• 11 years ago

A blanks don't have a projectile that breaks the speed of sound. Not sure that that would work.

jbob2000• 11 years ago

But why? Why do you want to know when a gunshot happens? By the time you've heard it, it's already too late.

“You were so focused on whether you could do it, you never stopped to ask whether you should.” - Jurassic Park

Shotspotter CEO Answers Questions on Gunshot Detectors in Cities

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