I was watching some mediocre movie where the actors were playing detective on an open hard drive. Weird, negative chars filled the hexdump, with an occasional readable string.
"It's an image!" the guy exclaimed upon reaching a "²¡¤³§«©±°something.jpg⊧⊤⊧⊩⌬".
"Let's see it!" said the chick.
The image is slowly loading.
"It looks digital", the guy wisely concluded.
No shit Sherlock! Wow, they actually did not use a VHS recorder on those platters, those are actual BITS, wow.
Fortunately there's at least one professional photo* guy on the webs who maintains that digital sensors are not intrinsically different than film when it comes to capturing images.
-----
* about 3/4 down the page: "there's nothing at all digital about that look".
Monday, September 29, 2008
Wednesday, September 24, 2008
puţa
It's now Google's turn to show me questionable advertising. True, this is not spam per-se, but it's close:
Translation:
Penis enlargement 6 cm - Total satisfaction or your money back. 100% Guaranteed, test it for free!
I find this situation truly alarming, as I usually receive useful advertisements in the WebClips, and I certainly believe Google to be a reputable company that adheres to higher standards.
Translation:Penis enlargement 6 cm - Total satisfaction or your money back. 100% Guaranteed, test it for free!
I find this situation truly alarming, as I usually receive useful advertisements in the WebClips, and I certainly believe Google to be a reputable company that adheres to higher standards.
Tuesday, August 26, 2008
waste
Look at what people at some Indian atomic research center are producing.
Simply put, the guy comes up with a "clever" way to measure stuff using a lot of "general purpose" chips, instead of the obvious, straightforward solution that everyone uses: a programmable microcontroller. He gives a complicated schematic that underutilizes an expensive component and needlessly employs another expensive component. It's more of a novelty, an academic curiosity (though not a particularly interesting one), than a sane product.
Table 1 below lists approximate prices for the components in the guy's design:
Table 1: Guy's Bill of Materials
*not an actual "general purpose" component, at least not as general purpose as a 74LS chip, and certainly less general purpose than a microcontroller; to save money, it could be replaced with just the FTDI IC, crystal and USB socket, because you don't actually need to include a prototyping module in a production device (unless you can't solder SMD).
**the weakest performance variant
***74LS parts could probably be found for cheaper, for instance $0.37 for the '164 at www.ti.com, but for 1000 units.
****implied, part number not listed on schematic
So that's 42 bucks just for the parts. Given that there are a lot of parts, the PCB is going to be big, so that's also going to cost a bit. Also, using just 8 of the 12 bits the 15-dollar ADC gives out, now that's pure waste. Nobody gives a crap about a data acquisition system that gives 8 bits (256 levels), unless it's very very fast, which this isn't. The author states that the system can be modified to make use of the full 12 bits, which is reasonable, but no schematic is given, and I have a hunch it would require at least one more 74LS chip.
Now here's the proper way to do it. A lot of manufacturers offer microcontrollers with integrated USB circuitry, as well as on-chip ADCs. So there go the two most expensive components. Plus, a microcontroller, being programmable, that is, having code, and memory, can do a lot more interesting functions such as calibration, unit translation, alarms, outputting control signals, whatever. Plus, a lot of microcontrollers have many analog inputs, so they can measure more than one thing, unlike the guy's design. And they're cheap, very cheap.
My idea would be to use an AVR microcontroller, such as the ATmega8. Using the software-only USB implementation kindly provided by obdev, and the internal ADC of the ATmega8, I can measure 8 voltages with 10 bit resolution (4 times finer than the guy). Moreover, I can increase the resolution in software by using oversampling. Well he can do that too actually, but I can do it in firmware which is nicer. And my PCB will be much smaller and cheaper, because I only use ONE integrated circuit instead of 6. Table 2 below lists my costs:
Table 2: Proper Bill of Materials
As you can see, it's much cheaper, and much simpler to manufacture (therefore even cheaper). It will be slower and it probably won't pass USB certification, but it works. Using a proper USB microcontroller would make those two problems vanish and still cost no more than about fifteen bucks.
Table 3 below summarizes the results of my analysis:
Table 3: Comparative Wastage
There. More than 18 times cheaper, and much better specs. Waste.
Simply put, the guy comes up with a "clever" way to measure stuff using a lot of "general purpose" chips, instead of the obvious, straightforward solution that everyone uses: a programmable microcontroller. He gives a complicated schematic that underutilizes an expensive component and needlessly employs another expensive component. It's more of a novelty, an academic curiosity (though not a particularly interesting one), than a sane product.
Table 1 below lists approximate prices for the components in the guy's design:
Component Price Link
-------------------------------------------------------------------
DLP-USB245M* $25 http://www.dlpdesign.com/usb/usb245.shtml
MAX187CCPA** $14.81 https://shop.maxim-ic.com
74LS164*** $0.49 http://www.futurlec.com/IC74LS00Series.shtml
74LS90 $0.49
74LS74 $0.29
74LS132**** $0.30
R,C etc. negligible
--------------------------
Total $41.38
Table 1: Guy's Bill of Materials
*not an actual "general purpose" component, at least not as general purpose as a 74LS chip, and certainly less general purpose than a microcontroller; to save money, it could be replaced with just the FTDI IC, crystal and USB socket, because you don't actually need to include a prototyping module in a production device (unless you can't solder SMD).
**the weakest performance variant
***74LS parts could probably be found for cheaper, for instance $0.37 for the '164 at www.ti.com, but for 1000 units.
****implied, part number not listed on schematic
So that's 42 bucks just for the parts. Given that there are a lot of parts, the PCB is going to be big, so that's also going to cost a bit. Also, using just 8 of the 12 bits the 15-dollar ADC gives out, now that's pure waste. Nobody gives a crap about a data acquisition system that gives 8 bits (256 levels), unless it's very very fast, which this isn't. The author states that the system can be modified to make use of the full 12 bits, which is reasonable, but no schematic is given, and I have a hunch it would require at least one more 74LS chip.
Now here's the proper way to do it. A lot of manufacturers offer microcontrollers with integrated USB circuitry, as well as on-chip ADCs. So there go the two most expensive components. Plus, a microcontroller, being programmable, that is, having code, and memory, can do a lot more interesting functions such as calibration, unit translation, alarms, outputting control signals, whatever. Plus, a lot of microcontrollers have many analog inputs, so they can measure more than one thing, unlike the guy's design. And they're cheap, very cheap.
My idea would be to use an AVR microcontroller, such as the ATmega8. Using the software-only USB implementation kindly provided by obdev, and the internal ADC of the ATmega8, I can measure 8 voltages with 10 bit resolution (4 times finer than the guy). Moreover, I can increase the resolution in software by using oversampling. Well he can do that too actually, but I can do it in firmware which is nicer. And my PCB will be much smaller and cheaper, because I only use ONE integrated circuit instead of 6. Table 2 below lists my costs:
Component Price Link
-------------------------------------------------------------------
ATmega8-16AU $2.23 http://nuhorizons.com
USB socket $0 - low-speed device mandates captive cable
(like in USB mice)
R,C,D etc. negligible
PCB less than the other guy's
--------------------------
Total $2.23
Table 2: Proper Bill of Materials
As you can see, it's much cheaper, and much simpler to manufacture (therefore even cheaper). It will be slower and it probably won't pass USB certification, but it works. Using a proper USB microcontroller would make those two problems vanish and still cost no more than about fifteen bucks.
Table 3 below summarizes the results of my analysis:
Designer Price (excl. PCB, enclosure etc.)
-----------------------------------------------
Atomic Guy $ 41.38
Me $ 2.23
Table 3: Comparative Wastage
There. More than 18 times cheaper, and much better specs. Waste.
Saturday, July 26, 2008
idiocy
1. I stumbled upon some show on some channel where they were showing some stuff and then blurring some other stuff "for security reasons" or something like that. Good thing I don't remember. If the stuff they were blurring out was in fact real and not some "reconstruction", they'd have made a terrible mistake. Blurring doesn't "delete" any information, it just "scrambles" it. Furthermore, it's a poor scramble. Blurring does what's called a convolution, which is basically adding pixels to their neighbors. They can be easily subtracted - the frame can be deconvolved, revealing the original image. It's being used to enhance pictures that come out defocused or otherwise distorted (by analog convolution versus the digital blurring you do in the GIMP). So I hope those sequences were bogus.
2. News are getting dumber by the day. Besides the presenter obsesivelly calling some kids who pretended to sell stuff on some websites, without actually sending the items, hackers, which is insulting to all hackers on many levels, some other dude was reporting on the way cool "thousands of decibels" at some concert the actual TV station was organizing. Yeah, i'd have liked having a few thousand dB SPL there... any increase in news quality is welcome; though anything above a mere 200 dB isn't physically sound anymore, it's a blast shockwave, a concept similar to the one discussed near the end of the previous (relevant) post.
2000 dB SPL (the smallest that could count as "thousands") equals about 2*10^95 pascals (notably, almost one googol, or "ten duotrigintillion":), of them). Normal air pressure is about 10^5 Pa, or 2{90 zeros} times less.
Having failed to find what the pressure is inside a neutron star, the densest object known, let's calculate a very rough estimate. The average density of such an object is thought to be about 10^17 kg/m^3, although it varies from the surface to the center in a way I don't know, so this limits the accuracy of my calculation. Anyway, the pressure dp contributed by a layer of thickness dx at distance x from the center is dp(x) = rho(x)g(x)dx. The gravitational acceleration g(x) = Gm(x)/x^2, where m(x) is the mass contained in the sphere of radius x. Assuming a constant rho(x) for simplicity and lazyness to search for data, dp(x) = G*rho^2*(4/3)pi*x*dx. Integrating over x from 0 to R we get the pressure in the center of a homogenous sphere of density rho and radius R: p = 2/3 pi G rho^2 R^2. In terms of its mass, that would be p = 3/8pi G M^2/R^4 (the smaller, the more crushing). Doing the numbers, I get around 1.4*10^32 Pa, which is of course much, much, much less than 2*10^95; any other more accurate model would still give a result that's much, much, much less than 2*10^95. So on second thought, I wouldn't like having "thousands of decibels" anywhere, if that were possible.
2. News are getting dumber by the day. Besides the presenter obsesivelly calling some kids who pretended to sell stuff on some websites, without actually sending the items, hackers, which is insulting to all hackers on many levels, some other dude was reporting on the way cool "thousands of decibels" at some concert the actual TV station was organizing. Yeah, i'd have liked having a few thousand dB SPL there... any increase in news quality is welcome; though anything above a mere 200 dB isn't physically sound anymore, it's a blast shockwave, a concept similar to the one discussed near the end of the previous (relevant) post.
2000 dB SPL (the smallest that could count as "thousands") equals about 2*10^95 pascals (notably, almost one googol, or "ten duotrigintillion":), of them). Normal air pressure is about 10^5 Pa, or 2{90 zeros} times less.
Having failed to find what the pressure is inside a neutron star, the densest object known, let's calculate a very rough estimate. The average density of such an object is thought to be about 10^17 kg/m^3, although it varies from the surface to the center in a way I don't know, so this limits the accuracy of my calculation. Anyway, the pressure dp contributed by a layer of thickness dx at distance x from the center is dp(x) = rho(x)g(x)dx. The gravitational acceleration g(x) = Gm(x)/x^2, where m(x) is the mass contained in the sphere of radius x. Assuming a constant rho(x) for simplicity and lazyness to search for data, dp(x) = G*rho^2*(4/3)pi*x*dx. Integrating over x from 0 to R we get the pressure in the center of a homogenous sphere of density rho and radius R: p = 2/3 pi G rho^2 R^2. In terms of its mass, that would be p = 3/8pi G M^2/R^4 (the smaller, the more crushing). Doing the numbers, I get around 1.4*10^32 Pa, which is of course much, much, much less than 2*10^95; any other more accurate model would still give a result that's much, much, much less than 2*10^95. So on second thought, I wouldn't like having "thousands of decibels" anywhere, if that were possible.
Monday, June 30, 2008
Saturday, June 21, 2008
noise
Mkay... some ex-convict, who also happens to be famous, is denied entry in the UK. The UK rules, I love the UK. I fully agree with the British Border Agency: "we continue to oppose the entry to the UK of individuals where we believe their presence in the UK is not conducive to the public good". (In one way or another.)
Mkay... stupid mascot causes floods, or maybe it's just that Chinese symbolism is dumb and outdated. Also, those mascots are hideous. While we're at it, why don't we just shift all those eights a little bit? (pausing for a few moments) Aha! so that's how one transmutes prosperity to death and darkness to light etcetera. Interesting, I've learned something today.
Mkay... A lot of time has passed and people are still discussing Pluto. It's still amazing to see how much time and energy people invest in such irrelevant matters. Gravity Probe B canceled on the home stretch? Anyone? Bah! Pluto! You know what? Fuck Pluto and fuck the Hubble telescope for not being able to snap a photo of Pluto that's more than six pixels wide. We have pictures of Neptune, both from deep-space probes and from that orbiting piece of scrap that's been launched in space without being properly tested first, but we have great difficulty in obtaining pictures of Pluto. We also know there are bodies larger than Pluto beyond it and we don't call them planets, but we're still giving a shit about that piece of crap that can't even hold it's own orbit. We've failed as a race.
Mkay... crazy fanatic preacher admits to inscribing "an X, not a cross" on students' arms. A-ha! So not all terrorists are Muslim! We've learned something today, haven't we? The interesting thing is that he used "a science tool known as a high-frequency generator" to do what he did. This warrants further comments:
1. On the one hand, what he did is obviously wrong on many levels, but why the hell did he have to use an RF generator? I said this before in a previous post, concerning laser pointers: a knife can be used to prepare food, to heal people through surgery, or to kill people. Are you ready to ban knifes just because they can be used to kill people? I don't want to live in a world where I'm not allowed to use an RF generator because it can be used to burn people or cause interference. I know the article isn't about this, but I feel the problem needs to be raised. There also remains the question: why the hell use an RF generator, which is intrinsically evil and satanic as per the Bible, when there are matches and cigars and stuff available?
2. On the other hand, the guy might actually earn some bonus points for his technique. I mean, that's being inventive. It has hack value. For instance, if I had an RF generator and wanted to draw stuff on my skin, I'd certainly consider using it for that purpose, but maybe I wouldn't be thinking about this, had it not been for this guy's misdeeds.
Mkay... I was simulating some low-power wireless network and it wasn't working. No packets would get from one node to another. After countless hours of digging through the sources (I was lucky I had the sources), I found out that the simulated noise what at a constant level of plus 127 dBm. Sadly I can't give a fancy link to Google Calculator because it doesn't seem to know dBm, but I can tell you that's huge. I mean just look: Wikipedia has tables that speculate on how a hundred yottameters look like, but its dBm-to-watts table stops at 80. To get 127 dBm of noise power, or 5 gigawatts, you'd have to be inside a fusion reactor, or better yet, a hydrogen bomb. Well, the radio simulator would detect a collision at anything above -70dBm (like the physical chip does), which, as the Wikipedia table states, is quite a reasonable value. Anyway, fuck that, and fuck the fact that the interface for specifying noise in the radio simulation changed from TinyOS 2.0.0 to 2.0.1, breaking compatibility and silently failing (at least in the code I was working on, which I admit is... particular). You know what? Fuck bad programming, and fuck such a lousy sense of physics. This however raises the question: If I wrote a simulator from scratch, would I give debug warnings when parameters go haywire? Of course not, if only because there is no clear threshold after which a value can be safely identified as being totally insane. Maybe I should submit a patch that simulates the RF chip instantly vaporising into a greenish puff of smoke, so hot that even all the magic's gone away. I mean, if they simulate noise and attenuation and collisions and bit errors, why not?
Mkay... stupid mascot causes floods, or maybe it's just that Chinese symbolism is dumb and outdated. Also, those mascots are hideous. While we're at it, why don't we just shift all those eights a little bit? (pausing for a few moments) Aha! so that's how one transmutes prosperity to death and darkness to light etcetera. Interesting, I've learned something today.
Mkay... A lot of time has passed and people are still discussing Pluto. It's still amazing to see how much time and energy people invest in such irrelevant matters. Gravity Probe B canceled on the home stretch? Anyone? Bah! Pluto! You know what? Fuck Pluto and fuck the Hubble telescope for not being able to snap a photo of Pluto that's more than six pixels wide. We have pictures of Neptune, both from deep-space probes and from that orbiting piece of scrap that's been launched in space without being properly tested first, but we have great difficulty in obtaining pictures of Pluto. We also know there are bodies larger than Pluto beyond it and we don't call them planets, but we're still giving a shit about that piece of crap that can't even hold it's own orbit. We've failed as a race.
Mkay... crazy fanatic preacher admits to inscribing "an X, not a cross" on students' arms. A-ha! So not all terrorists are Muslim! We've learned something today, haven't we? The interesting thing is that he used "a science tool known as a high-frequency generator" to do what he did. This warrants further comments:
1. On the one hand, what he did is obviously wrong on many levels, but why the hell did he have to use an RF generator? I said this before in a previous post, concerning laser pointers: a knife can be used to prepare food, to heal people through surgery, or to kill people. Are you ready to ban knifes just because they can be used to kill people? I don't want to live in a world where I'm not allowed to use an RF generator because it can be used to burn people or cause interference. I know the article isn't about this, but I feel the problem needs to be raised. There also remains the question: why the hell use an RF generator, which is intrinsically evil and satanic as per the Bible, when there are matches and cigars and stuff available?
2. On the other hand, the guy might actually earn some bonus points for his technique. I mean, that's being inventive. It has hack value. For instance, if I had an RF generator and wanted to draw stuff on my skin, I'd certainly consider using it for that purpose, but maybe I wouldn't be thinking about this, had it not been for this guy's misdeeds.
Mkay... I was simulating some low-power wireless network and it wasn't working. No packets would get from one node to another. After countless hours of digging through the sources (I was lucky I had the sources), I found out that the simulated noise what at a constant level of plus 127 dBm. Sadly I can't give a fancy link to Google Calculator because it doesn't seem to know dBm, but I can tell you that's huge. I mean just look: Wikipedia has tables that speculate on how a hundred yottameters look like, but its dBm-to-watts table stops at 80. To get 127 dBm of noise power, or 5 gigawatts, you'd have to be inside a fusion reactor, or better yet, a hydrogen bomb. Well, the radio simulator would detect a collision at anything above -70dBm (like the physical chip does), which, as the Wikipedia table states, is quite a reasonable value. Anyway, fuck that, and fuck the fact that the interface for specifying noise in the radio simulation changed from TinyOS 2.0.0 to 2.0.1, breaking compatibility and silently failing (at least in the code I was working on, which I admit is... particular). You know what? Fuck bad programming, and fuck such a lousy sense of physics. This however raises the question: If I wrote a simulator from scratch, would I give debug warnings when parameters go haywire? Of course not, if only because there is no clear threshold after which a value can be safely identified as being totally insane. Maybe I should submit a patch that simulates the RF chip instantly vaporising into a greenish puff of smoke, so hot that even all the magic's gone away. I mean, if they simulate noise and attenuation and collisions and bit errors, why not?
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