What's an infrasound pulse generator?

March 21, 2009 10:29 AM

This Audi R8 "Blackbird" is fitted with an "infrasonic pulse generator" mounted in the front. So what is an "infrasonic pulse generator" ... is this a real device that actually does something?

I'm guessing from the large power consumption and need for liquid cooling, it must be some sort of barrage jamming equipment? But what does infrasonic mean in this context? I would think for any sort of jamming of the K/Ka band frequencies he'd need to hit those frequencies?

I guess it could be a weapon, would an infrasonic pulse travel through a car to disorient the driver? Would it be that small? Is that what infrasonic weapons look like?

posted by geoff. to Science & Nature (37 answers total)

7000 watts? What's he powering it with, a Mister Fusion unit in the trunk?

I also love the nice stealth look of a giant box screwed onto the nose of an expensive supercar.

I suspect the only thing it's actually generating is internet buzz.
posted by mr_crash_davis mark II: Jazz Odyssey at 10:47 AM on March 21, 2009

This is a sonic, not an electromagnetic device, so there's no possibility of interfering with the K, Ka, or any other section of the spectrum on any significant level.

As to what it does, beats me.
posted by valkyryn at 10:51 AM on March 21, 2009

My guess (addressed in the linked article) is some kind of deer whistle/wildlife warning.
posted by deadmessenger at 10:54 AM on March 21, 2009

Either it's a glorified deer whistle, or they have a range sensor to tell you if you're going to bump into something when parking or driving.
posted by zippy at 10:54 AM on March 21, 2009

Or maybe it's some technique to minimize air turbulence.
posted by zippy at 10:55 AM on March 21, 2009

My guess is it's meant to defeat automatic traffic control cameras, which are triggered by the pressure pulse of vehicles passing over them.

This thing would generate a welter of confusing pressure pulses which would cause premature firing of cameras or none at all because of noise filtering.
posted by jamjam at 10:57 AM on March 21, 2009 [2 favorites]

Valkyrin, just wild speculation, but if they could create enough turbulence in front of the car, perhaps it could reflect radar (see also weather radar).
posted by zippy at 11:01 AM on March 21, 2009

Response by poster: I found another link with a better picture. There appears to be writing on the right side, next to the lens contraption, which would be an indication that this is at least partially an off-the-shelf device? If you scroll to post #34, someone claiming to have something to do with making the device:

1) Environmentally sealed mil-spec data port. Only used for adjustments and uploading settings. Power is fed by 7000 watt peak modified sinewave inverter. Power connections are not visible in this picture.

2) Coolant lines are low pressure UL 94 VO Rated ultra high purity perflouroalkoxy tubing with stainless steel quick disconnect bayonet fittings. Pressure tested up to 60 PSI at 300 degrees F. Maximum operating temp on unit is 190 degrees. PVC tubing is rated to 140 degrees max. PFA tubing is tested to -350°F to 500°F.

3) The unit is not powered up in this picture. For safety reasons, it is never operated while the vehicle is stationary or when people are in front of it. The bubbles are due to the fact that the unit is removed regularly for cleaning and adjustments. The air bubbles are bled off and cleared when the coolant pump begins to operate.

4) The liquid is tinted green and is low conductivity (0.36 micro Siemens). It is not anti-freeze. It is non-toxic and UV reactive.

5) On this point you are partly correct. This unit is not available to the public. It is not United States military technology and therefore does not fall under any military classification...yet.

Mil-spec data port? What the hell does that mean?
posted by geoff. at 11:13 AM on March 21, 2009

Mil-spec data port? What the hell does that mean?

Military spec? As in, able to withstand environmental extremes? Just a (totally uneducated) guess.
posted by saladin at 11:21 AM on March 21, 2009

The guy is fucking around. Betcha anything it's just an empty chassis of some old military gear that doesn't do anything. All the "I will neither confirm nor deny" goofiness on that forum makes me lean further towards "fucking around".
posted by DecemberBoy at 11:25 AM on March 21, 2009

It'll be a deer deflector, I expect. Not just to warn them, but to physically clear them out of the way. I imagine a 7kW ultrasonic pulse will blow anything deer-sized (and smaller) clean off the road. Which is why it's never operated with people standing in front of it - it'd knock them over. Note that, while the deer thing is dismissed in the article because there's no way it could be operated continuously, it's not meant to be operated continuously. It's a PULSE generator, not a frequency generator. It'll get fired on demand when something appears in the car's radar/night vision/viewport.
posted by Beautiful Screaming Lady at 11:27 AM on March 21, 2009 [1 favorite]

7000 watts? What's he powering it with, a Mister Fusion unit in the trunk?

For some reason it's conventional for car audio amplifiers to claim impossibly large power outputs. Perhaps that number just means "it's a car audio amplifier".
posted by Mike1024 at 11:29 AM on March 21, 2009

Found later in that same thread, this seems like the coolest theory of the bunch:

"it's a liquid cooled IR imager. it's useful because its operation is independent of visible lightwhich means, when they hit their light/kill switches they can hit the strobes and keep going. everyone chasing them with light enhancing night vision (most readily available setups) will be unable to follow due to the strobe effect. meanwhile they (R8) can keep going."
posted by nitsuj at 11:30 AM on March 21, 2009

You know, if this device was developed with military applications in mind, I'd say it was meant to trigger land mines ahead of being right on top of them.

But I still think that-- on this car-- its purpose is defeating automatic cameras and other automatic speed monitoring devices.
posted by jamjam at 11:35 AM on March 21, 2009

"mil-spec data port" probably just indicates that it's a mil-spec style connector, like these. These are fairly common in industrial and research electronics, because they're standardized, fungible, and mechanically robust (more so than the molex connectors most of your car is wired together with). They're also much more expensive.
posted by 7segment at 11:53 AM on March 21, 2009

The term "infrasonic" is a curious one. The infra- prefix means "low" and is the opposite of ultra- hence infrared and ultraviolet.

If we read it literally it would mean it was producing low frequency sound, presumably below 20 Hz.

I think this guy is just playing buzzword bingo.
posted by Chocolate Pickle at 12:20 PM on March 21, 2009

Rarely am I so powerfully overcome by a desire to possess something the function of which I cannot begin to fathom.

nthing the deer deterrent theory. Deer grunt to threaten or warn of danger. It's a very low, surprisingly loud and powerful sound. It can be heard for quite some distance. Perhaps, like whales, deer can hear frequencies that are too low for humans to hear. Also, unless I mis-remembering something from high school science class, low frequency sounds travel further than high frequency sounds.
posted by Baby_Balrog at 12:21 PM on March 21, 2009

...claim impossibly large power outputs...

Is it really that impossibly large? 7,000 watts is 70 100 watt light bulbs. Wikipedia says that an automobile creates about 25,000 watts while "cruising" (whatever that means).
posted by niles at 12:30 PM on March 21, 2009

You're all wrong.

It's a front mounted microwave emitter designed to fry vehicle electronics.

In the event the car is being blocked by a car in the front (presumably a police car) the driver hits a switch, the car in front stalls and coasts to the side of the road while the Audi has a clear path to make a getaway.

If you watched the video you'll note that the off-screen owner jokes that you shouldn't stand in front of it if you ever want to have children...
posted by wfrgms at 12:36 PM on March 21, 2009

Ever try to make a right turn during lunch hour in midtown, Manhattan?
posted by Zambrano at 12:46 PM on March 21, 2009

It seems pretty apparent that the device in question is designed to decrease the aerodynamic efficiency of an otherwise beautiful car with the possible side benefit of baffling the front air intake. I am not surprised Alex Roy, who basically uses these illegal street racing events as an opportunity to explore his cosplay fetishism, is involved.
posted by danny the boy at 12:50 PM on March 21, 2009

I too cast a vote for "he's fucking around". It doesn't do anything, some of the ideas here are reasonable, others are way off the wall. That's the response he wants.
posted by Science! at 12:56 PM on March 21, 2009

It may be an infrared generator, some kind of strobe light. There are two ways to generate IR: either with a bunch of LEDs, or with a light bulb that also generates visible light (which you have to filter out). Only the latter would require any kind of cooling.

It may be an infrared imager. There are two major breeds of IR imaging devices, near IR and far IR. Near IR imagers are what we usually call night-vision cameras. They do not require any kind of cooling, but they do look a bit like the device in the image, with a yellow lens to block out some visible light.

The other type of infrared imager is called a far IR imager, also called a thermal imager or a FLIR. These do require cooling, usually liquid cooling. It looks like there has been some effort to install these in cars to help spot deer (example). The lenses on far IR imagers are made of metal that looks like a mirror to us but is transparent to IR rays.

So it's not a near IR imager, since that would not require cooling. It's not a far IR imager, since that wouldn't have a yellow lens. It must be an IR generator.

But why would you mount an IR generator on the front of a car? Maybe to blind night-vision cameras. Maybe to blind poorly designed regular cameras, which sometimes don't filter out IR light effectively. Or maybe to trigger the signal priority switches installed in many cities, which respond to IR light in a particular frequency range (originally designed to let firetrucks get a green light faster) -- but an LED IR generator would work fine for that purpose.

Or maybe it's just a random piece of military equipment strapped to the front to confuse everyone.
posted by miyabo at 1:00 PM on March 21, 2009

you have a lot of faith in the green if you ask something here everyone there is speculating about. too bad you're only getting speculations.

but hey, let me chime in with my own speculation: it's a trick to get attention by some rather shallow child.
posted by krautland at 1:04 PM on March 21, 2009 [1 favorite]

Maybe he just wants to drive up to one of those nuisance-noise-generating-stereo kids and blow out their windows. Because before I moved last month, I would have paid good money to use that on my asshole neighbor.

"Before 10 pm I can make as much noise as I want."
posted by ctmf at 1:08 PM on March 21, 2009

Is it really that impossibly large? 7,000 watts is 70 100 watt light bulbs.

Sorry, I meant to say I find the claims of car audio manufacturers impossible to believe.

You're right that it would be possible to continuously draw 7,000 watts from a car engine; I just don't believe that the audio amplifiers that claim they do, actually do.
posted by Mike1024 at 1:11 PM on March 21, 2009

Since we are all speculating here, I am going to go with it being a device to thwart night vision goggle wearing deer who may rat these guys out to the cops.

Can it have multi-purposes?
posted by JohnnyGunn at 1:18 PM on March 21, 2009

Maybe the ultralow sonic frequencies thwart cops with radars by making them want to go poopoo.
posted by Blazecock Pileon at 1:39 PM on March 21, 2009

It doesn't do a damned thing (or, at least, it doesn't make any damned infrasonic sounds). Even if he were delivering 7,000 watts to that "speaker", he's got it mounted to the front of the car with four small bolts. A JBL cinema subwoofer "only" handles a max of 4800 watts, and movie theaters typically have their sound systems mounted in solid concrete walls. And they still make the room shake.

If that were a real "infrasound pulse generator" and it was really throwing out 7000 watts of sub-subwoofer sound for any duration it would tear itself from the frame of the car.
posted by Benjy at 1:39 PM on March 21, 2009

You're right that it would be possible to continuously draw 7,000 watts from a car engine

Wouldn't that be not so much possible as easy? I mean 7000 watts isn't even 10 hp.
posted by ROU_Xenophobe at 2:00 PM on March 21, 2009

but hey, let me chime in with my own speculation: it's a trick to get attention by some rather shallow child.

Bolted onto an R8 it brings the phrase "coals to Newcastle" to mind.
posted by Lentrohamsanin at 3:55 PM on March 21, 2009

Some newer German cars have systems for measuring the distance between you and the car in front of you, to use either for driver-warning purposes or as part of the cruise control. Mercedes (I think) has a cruise control system that will apply the brakes if the car in front of you starts to get too close, in fact.

Although I don't know how well infrasonics would work for distance measurements at high speed, that might be connected. I'd have imagined that it used radar or laser, but I guess you could do it with sonar as well, and it might not get into the regulatory problems that an RF or laser-based solution would. (Frequency bands you'd be able to use would probably be different in Europe versus the U.S., etc.)

Also, just because something is "7000 watts" doesn't mean it's necessarily that huge. Remember: watts are a rate. If you use 7000 watts for 0.01 seconds, you've only dissipated 70 joules of energy. When I was an undergrad, I played around with a multi-megawatt laser system that ran off of a power supply that plugged into a regular 120V socket. It was several megawatts, but put out that power only for a tiny fraction of a second. It sounded way cooler on paper than it actually was. Wattage is meaningless without also knowing a device's duty cycle.
posted by Kadin2048 at 6:01 PM on March 21, 2009 [1 favorite]

From geoff's second link:

5) On this point you are partly correct. This unit is not available to the public. It is not United States military technology and therefore does not fall under any military classification...yet.

I will neither deny nor confirm your conclusion in any public forum.

This sounds like douchebag-ese for (a) I don't understand what it does, or (b) Duh, it looks cool, that's all.

Note that there's a significant possibility that use of the term infrasonic was accidental (or intentionally wrong), where it is actually infrared or ultrasonic. I think those would make more sense, such as an IR jammer against laser guns.
posted by Simon Barclay at 8:22 PM on March 21, 2009 [1 favorite]

Response by poster: I do agree that there's a large level of douchebag-ese all across the board, and the whole "classified military' talk is very tongue in cheek. At least my knowledge of physics was reassured. I'm guessing that if it really needs liquid cooling it has to be a FLIR camera. There's not many electronic devices I can think of that would be used for street racing, need to be mounted to the front of the car and require liquid cooling.

I believe the priority devices at intersections require a specific code be sent to them via strobe, and every jurisdiction has a different code.
posted by geoff. at 9:35 AM on March 22, 2009

Speedtraps and the motorist.

The speedtraps can include various devices but the majority can be divided into 2 main categories, static and mobile.
The static speedtraps mainly consist of Gatso cameras operated by radar, SPECS cameras, operated by measuring your average speed between 2 cameras and Truvelo, operated by pressure sensors in the road.

Truvelo - Static - Pressure Sensors
These Truvelo cameras use pressure sensors in the road to be activated. A speeding car passing over the pressure sensors too quickly will activate the camera to take an image, this is forward facing so is capable of taking a picture including the driver.

Don't you think you could have taken a moment to Google this before posting, odinsdream?
posted by jamjam at 12:05 PM on March 22, 2009

Wouldn't that be not so much possible as easy? I mean 7000 watts isn't even 10 hp.

True, but few cars come with alternators which would put out 7000 watts of electrical power, which on a car with a 12 volt electrical system, would be some 580 amps.

Admittedly, one could fit the engine with a large alternator (such as one might find on a large truck or ambulance); switch to a car with a hybrid power system and draw power from that; or simply put a generator in the trunk; however none of these would fit my criteria for 'easy'.
posted by Mike1024 at 3:33 PM on March 22, 2009

Apology accepted-- thank you very much.

Both my first and second links describe the Truvelo system as static as opposed to mobile; take a look at the photograph accompanying the second, it looks permanent to me, but i could easily be mistaken. Other sites say the Truvelo sensors can be "on or under the road surface" and describe the sensors as piezoelectric pressure sensors.

However, as I go through these sites I see a lot of incoherence and self-contradiction. It's conceivable to me that your original assertion is more reliable than they are.
posted by jamjam at 8:24 PM on March 22, 2009