Catch up on stories from the past week (and beyond) at the Slashdot story archive

 



Forgot your password?
typodupeerror
×

Comment Re:Creepy (Score 1) 188

I don't think the materials science is there to deal with forming/deforming a projectile on the order of 300,000 rpm (presuming a 1:7 twist & 3,000 fps).

Piezo actuators should have no problems working at up high tens of KHz, and even up in the hundreds. Peizo elements are used in tweeters, where they have to react up to at least 20 KHz, in the right range for this project. Piezos do not have much distance that they can travel, but at that speed, you might not need much distance. All you really need is a little paddle that can stick out an slow the bullet down on one side.

Comment Re:Alternate use for this technology (Score 1) 188

And here's a clue for you. NO one over there wants peace at all, ever.

Sorry, but many Muslims are taught to hate Jews from a very young age:
https://en.wikipedia.org/wiki/...

There are other examples, but this is the most famous one that I could think of.

From what I understand (and I know many American Jews who have visited Israel), the Jews pretty much just want to be left alone.

Comment Re:Creepy (Score 2) 188

You got it. Lasers are cheap... electronics are cheap... batteries are cheap... spoofing is cheap.

Really, as an engineer, I can imagine two ways for this thing to work, and it depends on if the projectile spins. Typically, bullets spin so that they act as gyroscopes -- always pointing the same direction (YouTube has videos of guys firing pistols into ice -- ice stops bullet which just sits there and spins like a top).

If the projectile spins, you can, in theory, guide it with a single fin that can extend or retract. You could not use a standard camera as such, because you are spinning wildly. Assume 2000 FPS bullets -- if you want to shoot a mile, you need at least this much. Also assume a 1-in-12 twist (real twists are in the range of 1-in-7 to 1-in-14, depending on shape and weights of bullet). That means that the bullet is spinning with a approximate rotation of 2 KHz. I doubt that you could have an effective regular camera spinning like that and still work. A better way would be to have a linear sensor (a line camera) that looks forward and to the side. This could operate. When you see a bright stop, see how far it is from the center. More off-center = kick your fin a bit more. This is simple and straightforward. However, since the bullet is spinning and you do not know when the camera will cross the laser, you probably need to keep the laser on full time. This is probably the easiest and cheapest way to accomplish this, but should be easily spoofed. You could maybe put a crypto on the laser signal by changing the intensity of the signal without turning it off, but it would have to be a much lower frequency than 2 KHz because that is your effective sample rate. If you assume 500 Hz signal (four-times oversampling), you would only get about 500 bits of data before you hit your target (assuming a target 2000 feet away). Is that enough to actually apply crypto? I am not sure...

On the other hand, if the bullet is NOT spinning, you can use a regular camera and regular fins to control it. In that case, it is entirely reasonable to embed some sort of cryptographic modulation on the signal. In any case, the existence of a 2-D sensor makes the bullet more expensive, and increases the amount of processing that needs to be done. It should, however, be more feasible to put crypto, but at greater cost.

Comment Re:Alternate use for this technology (Score 3, Insightful) 188

I don't get the US. I mean, by now you should have noticed that the bigger and more complicated the technology, the more you play into your opponent's hands. First of all, you're using high tech weapons in a low tech war. You can't really fire any round anymore that doesn't cost you more than what your target cost your enemy.

Off topic, I admit, but this reminds me of the current Isreal/Hamaas conflict. Just launch simple, dumb, and cheap unguided rockets from the Gaza Strip. Isreal has an "Iron Dome" defense system that is supposedly pretty effective at stopping them -- at $1,000,000 per shot. Great way to bankrupt an enemy...

Comment Re:Creepy (Score 1, Interesting) 188

Actually, this should not be scary at all! You just need to figure out the frequency and modulation of the laser used. Then, just make sure that you have such a laser pointed at the guy beside you. You are suddenly safe from snipers! Just make sure that you do not like the guy beside you.

Seriously, the only way this could be spoof-proof is to modulate the laser with some type of crypto.

Comment Re:Why 80% (Score 1) 278

Hey, Obama promised "Hope and Change." Isn't that what we have here? Admittedly, Bush started this -- probably. Or maybe he inherited the seeds from Clinton or earlier -- who knows how far back this trail goes? But Obama has had almost 6 years to fix things. Instead, under his watch, things have gotten worse.

In Obama's defense, I do not know if Romney would have done things any differently, but I suspect we would probably still be here even if he had won.

Privacy

William Binney: NSA Records and Stores 80% of All US Audio Calls 278

stephendavion sends a report at The Guardian about remarks from whistleblower William Binney, who left the NSA after its move toward overreaching surveillance following the September 11th attacks. Binney says, "At least 80% of all audio calls, not just metadata, are recorded and stored in the U.S. The NSA lies about what it stores." He added, "The ultimate goal of the NSA is total population control, but I’m a little optimistic with some recent Supreme Court decisions, such as law enforcement mostly now needing a warrant before searching a smartphone." One of Binney's biggest concerns about government-led surveillance is its lack of oversight: "The FISA court has only the government’s point of view. There are no other views for the judges to consider. There have been at least 15-20 trillion constitutional violations for U.S. domestic audiences and you can double that globally."

Comment Re:Wait a minute... (Score 4, Insightful) 162

I don't know about Acetaminophen, but I've heard compelling cases made that if Aspirin were discovered today it would be a prescription drug. Think of the side effects, the modern day "think of the children!" attitude, and pathetic need of the body politic to feel "safe" from any and everything.

Comment Re:USB DACs (Score 5, Interesting) 502

A USB audio interface also lies outside the electrically noisy interior of a PC chassis.

Strong caution with USB audio. There is a metric buttload of cheap USB adapters, While they technically work, they typically lack analog filtering that gets rid of higher harmonics. If you look at the output on an oscilloscope, instead of a smooth wave, you see the actual steps. Better audio hardware should have filters to smooth this stuff out.

Another MAJOR thing is inducing noise into the output. This is not just for USB cards, but all audio solutions. You need some pretty good filtering between the digital and analog power domains -- yet another area where cheap sound can skimp. Hey, let's shave $0.05 off by dropping this capacitor and inductor!

The original article really touches on two separate areas:
1) Audio processing
2) Higher quality audio circuitry

SoundBlaster (and other gaming-oriented cards) typically do both. However, do you really NEED both? The audio processing stuff is supposed to provide an API that games can use to make thing sound more realistic, or offload audio processing from software to hardware, or both. It can typically decode various dolby flavors, and do some other fancy DSP-ish type stuff. Do you really NEED all of that? If so, then maybe a gaming card is for you.

However, what if you want the best sound possible, the lowest noise possible, and don't really game or use the various audio enhancements? You just want a plain-vanilla sound card, but with the highest quality audio. Where to do? Skip the computer store, but go to your local MUSIC store (not the ones that sell CD's, the ones that sell GUITARS). Those cards skip all of the DSP bells and whistles, but have the best-quality DACs and filtering that you can find. You can find some really good USB solutions that will blow on-board audio out of the water for about $100 or so. Of course, you can go crazy and spend $500 or more if you want. If it is good enough for a music producer to use in a studio (who makes his or her living off of the sound), it is probably good enough for YOUR music and movies.

Slashdot Top Deals

We are each entitled to our own opinion, but no one is entitled to his own facts. -- Patrick Moynihan

Working...