That still seems problematic to me. If I am being arrested for, say, burglary, why should the cops need access to whatever personal data is on my phone?
If you had an accomplice, it is likely that his name and phone number will be in your phone. Maybe the name and number of your fence. I'd say that there was sufficient probable cause for a warrant to search your phone. After all, they're also going to get a warrant to search your house for stolen property.
Last I checked, even when you get arrested you have some rights (albeit fewer than a free man). So why would the default assumption be that you surrender the right to a private phone when arrested for a crime not involving the phone?
Dunno. Why are you making this assumption? The article talks about preserving potential evidence after an arrest but before the warrant is issued. You'll also lose your wallet and other contents of your pockets when you get booked, why would you think a phone would be exempt?
Yep. I also know how to create them when necessary containing any time you'd like in either LTC or VITC format (or burned into the image, if that's how you want it), and know that those time stamps are rarely shown on the news when the video is shown. I also doubt that too many camera phones create them in video they record, but even those that do can be "fixed" in post after editing.
I have no idea who you are talking to here. Certainly not me. But I do understand the qualifier "with all due respect", which is what people who have no respect for the other person say.
I have never seen any citizen-made cop recordings released that had any cut-edits in them, ever.
You don't watch the news much, then. Or you can't recognize cuts when you see them.
All the cop-on-tape stuff I've seen has been uploaded to YouTube as a public service, for free and at personal risk.
Yes, very risky, posting videos on YouTube. And I guess this answers the question of "don't watch the news much".
It's sad that you think that there is no possible way that any YouTube video could have been edited, even as simple an edit as to forget to post the first ten minutes of the cop/citizen interaction. You know, the part where the citizen is actively resisting arrest or doing something else violent, while the cop tries less physical means of dealing with it. You think that the interaction started with the citizen in a choke hold being handcuffed, because obviously the citizen could never have done anything to merit such treatment, and obviously the interaction began at that point in time and could not possibly have started before that.
What you have here is simply evil propaganda
Yes, I'd classify your comments that way. You are honest about your lack of respect for people whose opinion differs from you in this discussion, and honest about your participation. Refreshing.
Secondly, it's pretty bad that they posted the home addresses of a bunch of cops.
Why? Cops should have no expectation of privacy because they are public servants serving the public, and they actually are on-call 24/7, so of course they should expect no privacy in their homes, either.
Maybe this points out the dangers of vigilante hacking? We do it because we can and screw the consequences!
And of course, shouldn't the cops want to be recorded if they're not doing anything wrong? On TV, people being arrested often claim bogus police brutality or some such nonsense. In real life, having a bystander recording the situation could help them.
No, in real life, a recording of the situation will be edited to paint the cops in a bad light. Nobody gains much from releasing a tape of them doing things the right way. There are considerable advantages to selective editing. Like, edit out the abusive drunk throwing a punch or two at the cop, but leave in the cop shoving him up against the car and cuffing him. Sell that to the media, or to the drunk's lawyers who have conveniently filed a police abuse case...
Seems to me any cop that doesn't want themselves to be recorded while performing PUBLIC duties in PUBLIC places isn't confident that they're not going to get in trouble for doing something wrong.
More like they are pretty confident that the people who don't like cops (criminals, for one) will have no problem editing any tape to put the cop in the worst possible light and try to make it look like he did something wrong.
Well, Obama is literally a puppet, a mechatronic puppet; controlled by brainwaves from the fleet of orbiting spacecraft piloted by angels who protect us from the lizards. And....
Much simpler and more nefarious than that. He's receives his control messages from one or more visual cuing devices placed in front of him whenever he appears in public, which contain encoded messages for him to speak at the appropriate times.
You could use USB sticks, external drives and external printers on it.
Yes, I can see merit to USB sticks, but an external drive is going to pull way too much power to have much use. An external printer is going to give you about five minutes of battery life for your tablet.
But for a cellphone? No. Most cellphones ARE the USB stick.
Option 5: Attempt to negotiate with the potential host and if there is no response to negotiations assume you are connected to a dumb charger and consume the power you need, with the caveat that you limit yourself to what the supply can provide.
Standardising on 12V for laptops has the issue that sooner or later someone will get the "bright" idea to connect them directly to car electrics. That means you either have to design the devices to stand being connected to car electrics or you have to deal with the returns that result from idiots conecting an unsuitable power supply (and not admitted they did so of course).
What makes a power source "unsuitable"? Why, the design of the object connected to it, of course.
What makes a car 12V outlet unsuitable for a laptop? Variation of voltage in normal operation might be one thing, but a laptop can be designed to handle it. The sudden loss of power or brownout when starting? Yes, that can be designed around. In fact, a laptop is much better at dealing with this than many other things since a laptop has an internal battery which makes the laptop into a UPS.
So, if 12V becomes the standard, it would be a foolish laptop manufacturer that didn't take automotive electrical systems into account when designing the new power sections. There are so many reasonable apps for 12V powered computers that I'm actually surprised there aren't more of them already.
I've seen DC/DC converters specifically intended for such purposes -- 10-15V input, 12V output. It's not hard, and those converters are not magic.
Option 3: assume that you can take at least 100ma without negotiation and don't discharge completely while trying to negotiate via USB protocols with a dumb charger.
Option 4: start by taking 100ma, then try 150ma, then 200ma, until the port is shut down, then disconnect and allow the port to restore, and then draw the last known current.
See, two more options. Neither one requires smart chargers or special cables with munged data lines so they can't be used as normal USB cables.
The power supply may be perfectly happy putting out 20A but the wires leading to the outlet will have a maximum amperage before the melt. You can't tell that from a voltage drop.
That "melt" comes from heat, which comes from power dissipation, which comes from internal resistance, which causes a voltage drop. It's not rocket science, it is simple physics. While the battery you have connected the wires to may not show any voltage drop, the end of the wires connected to the charger will see it and can act upon it.
Of course, the ten amp fuse in the cigarette lighter plug any properly designed car charger will have will blow a long time before the 15 amp car fuse does, and the charger itself will be able to figure out that it is pulling 9 amps from a circuit that is rated at 10 amps (which is why cigarette lighter plugs have those 10A fuses in the first place) and shut itself down long before either fuse blows.
Then you could just plug your laptop into it's own USB port and you're all set!
That would be cool, I could power my laptop from its own USB port while I am busy copying my mp3s onto itself via USB! It has to work with USB2, though, because the volume of stuff I have to copy is too large and would take longer that one charging cycle otherwise.
Of course, I could always just turn the volume down and get done copying faster. I should have thought of that before.
Most power supplies already have a digital controller inside,
Citation required.
I have opened up a large number of wall-wart style power supplies and have yet to find any "digital controller" inside. The closest to anything digital I've found is in the switch mode supplies that use PWM to regulate.
In the example given above, what if the power supply is overspecced, but is on a 12V 10A fuse (as most/all car cigarette lighters are).
Put in a proper fuse. Or put a simple low value resistor in series.
If you are manufacturing a power supply for car use (i.e., cigarette lighter plug) then put that resistor (or any other current sensing system) INTO THE SUPPLY. Design your supply to limit itself to what you have. In fact, most of the cigarette lighter plugs on inverters or other supplies I have already have a 10A fuse built it, so those devices already know they can't draw more than that. If they do, then it is poor design on their part.
A properly specified power supply will never drop voltage to a point of current insufficiency in its usable range,
And that's why detecting a sag is a means of detecting a supply limitation without having to have the supply and the device both singing three part harmony trying to negotiate whether the supply will sink current or the charged device will source it.
but other pieces of the puzzle may not be up to task.
If you are going to design a standard that will solve the whole world's problems, don't forget there are hungry children in China and AIDS is rampant in Africa.
If you are going to limit your standard, you might as well limit it to something that will solve the problems of the vast majority of users and let the borderline cases be dealt with in other ways. E.g. if you use a car supply designed for a ten amp cigarette lighter socket on a 2A 12V supply, you deserve to get your fuses blown if the charger designer cannot detect a serious overcurrent issue and resolve it. There is no reason to expect a simple 2A 12V supply to have the smarts to negotiate with anything plugged into it for how much current it can draw or if you can put 12V back into the supply.
One thing I need more information, however. The standard industrial DC application uses 24VDC, where is the consumer electronic's 19VDC came from?
I assumed that the now common laptop 19V supply was based on the batteries being used. A voltage high enough that it doesn't need to be boosted to charge the batteries. From that, you can tack on all the other DC/DC converters pretty easily for lower voltages.
Although, someone else has posted that this voltage is based on the voltage for the backlight of the LCD display. I don't know. I don't believe it, since the backlight voltage has to be generated from the battery voltage when portable. If you have to have a circuit to produce that voltage anyway, then you save nothing. You only save if you make the incoming voltage optimized for the battery you have. Charging the battery is about the only thing you do while on shore power that doesn't happen when portable.
With negotiation the laptop can plug in and make a decision about whether or not there's enough power to do anything useful.
Nonsense. You don't need negotiation to determine this. Just watch the input VOLTAGE. If the voltage starts to drop as you pull more current, then the supply is limited and you need to do something about it. That takes NO intelligence in the supply other than the natural current limiting.
All that this negotiation adds is the requirement that you buy someone's smart charger instead of using the power you already have available. You can't hook your 20A 12V power supply up to your laptop to charge it because your laptop will be trying to negotiate with the supply. My 30A supply would power your laptop all day, except the laptop will shut itself off when it can't negotiate with my power supply. Nor would my bank of backup batteries be able to run that laptop, for the same reason. No, I would be forced to buy someone's smart charger and probably do a wasteful conversion of my 12V into 120AC just so I can plug the smart charger in somewhere.
Having your laptop decide what not to do based on the power supply it is plugged into is a different problem than finding out that the cellphone you just bought won't use any of the chargers you already own because it wants 6V and your chargers only do 5V, and it has a microUSB connector and your chargers are all mini-USB. And then finding out that the ebook you just bought, even though it claims to charge through the USB connector, won't charge unless it is connected directly to a host (a hub isn't good enough).
The latter problem doesn't need smarts, it only needs a standard voltage and connector. If I want to home-brew a charger for my phone based on the bank of solar-charged batteries I have, all I should have to do is get one of the right connectors and produce the right voltage. I shouldn't have to program some computer chip with the right protocols to negotiate what can be mandated by fiat.
Solving this problem with the same solution that you want for your laptop is vast overkill and will cost everyone else a lot of money they shouldn't have to spend.
The device needs communication to negotiate between the power adapter and the device to be powered. The device and power supply will communicate things like if it sourcing or sinking current (or capable of doing both), whether it is a battery, an intermittent supply like wind or solar, etc. It sounds pretty cool if manufacturers go along with it.
There's cool and then there is practical.
A cell phone isn't going to source power to anything. My PDA isn't going to source power to anything. My camera isn't going to source power to anything. My cell phone charger isn't going to sink power from anything. My computer isn't going to source power to anything (via the charging jack). It isn't going to sink power from anything (on the USB ports). My computer charger isn't going to sink power from anything except the mains, and if you build that charger with the same plug for the mains that you use for the device, you are stupid.
The problem is not that the devices we have are not smart enough, it is that the number of different voltages they were designed to source or sink is too large, and the number of different kinds of connectors is too high.
Laptops, in particular, already have the DC/DC conversion hardware built in to provide the internal voltages, and there is no reason that they cannot be built to accept a range of input voltages from 12 to 19 instead of frying themselves if you put 18.2V into an 18V connection. The same concepts that allow the now ubiquitous 100-250VAC wall warts would allow laptops to have a wide range of input voltages.
The only thing this complexity is good for is making an industry around supplying smart charging devices that they can charge extra for because they are smart, and shutting out small companies who want to fill niche markets but cannot afford the cost of a fullblown smart charging device, or private individuals who want to build their own.
Yes, a full-blown USB connection needs to have a smart communication system so the devices can tell the host what they are and etc. No, a device built to charge through a USB connection doesn't need to communicate shit, all it needs to do is see 5V on the input and assume that it is connected to something that will limit the current it will provide if necessary. That means you can use any 5V supply to charge it, whether that is a laptop, a battery, or a wind turbine.
Please stop this headlong rush into "cool" and settle for practical. These supposed requirements for communications really aren't necessary, at least not for the vast majority of charger/device issues. At the base level, a charger supplies a specific voltage and up to a certain current; any current draw over the limit can be detected by the device and it can either back off or the charger will shut off. Make that voltage a standard, and use a common connector, and the vast majority of issues go POOF! If there truly are border cases that demand this level of intelligence in devices and chargers, then apply those higher standards to THOSE DEVICES, but make the manufacturer justify it so they can't just claim "special case, you need to buy my special overpriced charger" like Sony does for their eReaders. If a laptop manufacturer says "we can't design a laptop that will take 19V input, so we need to have a special case 15.8V charger for it", they should be laughed out of the marketplace, not allowed to profit from stupidity.
Ever plug a GPS into a smartphone with USB? Usually the GPS says to itself "Oh look, a connection. I'll just charge up my battery...".
Why would your smartphone even try to put 5V onto the USB connection? Not very smart, I'd say. It shouldn't be acting as a host in that respect no matter what, given the battery capacity.
And this "standard" connector will suffer from the same problem it already does today: does the device look for a "charging device" or just power on the power pins?
Example: some Sony phones use the micro-USB connector to charge. (I don't know which models, I just know that there are "Sony chargers" that have this connector.) The Sony eReader uses the same connector.
The Sony phones apparently don't care if they are connected to a computer, they'll take power from the connector. The eReader DEMANDS that the USB host negotiate power requirements or it will happily discharge itself waiting to talk to the USB host. OR you put the appropriate shorts/loads on the data lines that tell it to charge anyway.
I got a pair of Sony "chargers" for Christmas so I could charge my eReader while travelling without a computer. No joy. "I'll just open up the charger and short the data lines to confuse the reader into charging" I thought. Also no joy. The Sony charger manufacturer saved money on the cable and used a two-wire cable. No data lines at all.
A better solution to the problem is to define a standard voltage that devices will accept for charging/operation. That's all. "Put 19V on the DC input, you get charging." For low power devices, "put 5.2V (USB) on the USB power lines".
Whatever provides the voltage is responsible for limiting the current to what it can provide. End of problem. But this "send a voltage request and ack and nak and then toggle this data line to 43 ohms and then draw 3 mA on the other data line and then look for a..." is just crap. Devices with a micro/mini/regular USB connector charge when 5V is applied. Devices with a standard XYZ connector take 19V. (Better would be 12V, but one standard at 19V is better than no standard at all).
You might want to look up "light field"; apparently it's a well-defined term within the field (which has some connections to what I'm familiar with and hence was talking about but is formulated differently for different application). In particular, "full light field" is different from "all the light rays".
I'm using the definition that Lytro has on their website, which I quoted in my first comment. Again:
The light field fully defines how a scene appears. It is the amount of light traveling in every direction through every point in space - it's all the light rays in a scene. Conventional cameras cannot record the light field.
Emphasis mine. Wikipedia's definition is essentially the same. The "all the light rays" bit is a natural result of saying "every direction through every point in space". The word "full" does not appear on that Wikipedia page, so I have to assume that it has the standard english meaning of "complete" or "all". If the "light field" is "all the rays", then the "full light field" cannot be a subset, it must, too, be "all the rays".
Measuring the full light field means measuring all the available information (in a different context you may be familiar with, if you work with light in any way, an analog would be a full Stokes polarimeter that measures all available polarization parameters of the light, not just one or two, as most cameras and filters do) in the light that the sensor receives,
So again, the claim that they are processing "the full light field" is misleading. They certainly are not processing all the available information, since clearly they aren't including polarization information (which they don't capture at all), even if you assume that "full light field" truly is not "the amount of light travelling in every direction..." as they define it.
I'll admit first that I myself wasn't familiar with the term "light field" and the term itself did sound a little sci-fi-y, but it is a valid, technical jargon, not just marketing speak or jibberish you see in sci-fi.
I had no problem with the term "light field", only with combination of the way they defined it and then the claim they were processing the "full light field", along with the implication that they were capturing more rays than a "conventional camera". That, and a lot of the other stuff on their pages like "You are a beautiful, unique snowflake." and "No more flat, boring, static photographs." (The "living pictures" certainly look flat and boring and static to me, so yes, there still are "flat, boring, static" photos available from their system, and unless places like Facebook and other photo sharing sites adopt the code to allow fancy adjustable focus pix most of the photos shared on the web will be flat and static, too. Boring is not well defined, so I'll not deal with that claim.)
You can't simultaneously not believe that they are claiming to construct a full 3D model and also believe that they are claiming to capture "all the light rays":
Yes, I can, because "constructing a 3D model" is what may or may not be done after processing the "full light field", which THEY define as all the rays passing through an object.
And "discarded" and "never measured" is the same thing, too.
Nonsense. "Discarding" information means you have something and gotten rid of it. "Never measured" means you didn't have that information to start with. Whatever information you did not measure from the photon is NOT MEASURED, it is not information that you are discarding. Otherwise you could simply NOT DISCARD it and you would still have it.
But that is an issue of syntax not really relevant to this discussion. The important part is that the website is filled with marketing-speak which is misleading, whether you think you can discard that which you didn't have to begin with or not. The "full light field" is not processed simply because they don't capture the "full light field"; whatever processing that could be done following that caputure is irrelevant.
I don't think they are claiming to build a full 3D model of the subject (that would indeed be sci-fi).
I don't think they are claiming that, either.
I do think they are claiming to use additional information usually discarded by conventional light sensors (i.e. CCD),
Not "discarded", it is never measured.
i.e. something that corresponds to the radius of curvature
No. It deals with the position of the focus, either in front of, on, or behind the image plane, which is the microlens array. Focus in front of the array and the resulting image on the sensor is either normal or reversed, I forget which. Behind does the opposite.
but the paper abstract talks about light rays, like the rays in geometric optics).
My comment was about the company website, which talks about "all the light rays", implying that it catches light rays that normal cameras do not. They don't catch any more than any other camera, they just don't use one pixel to detect one pixel's worth of them, they us a lot more. That gives them "direction" information.
What I am continually amazed by is just how large a range he and his band have. They do tons of different styles when parodying songs and do them extremely well.
I have lost count of the times I've been listening to a radio station and heard what I thought was a Weird Al song playing, then thinking "those aren't the right words", only to realize I was hearing the original artist doing their less-than-impressive original version.
And hearing an original song and thinking "that sounds so much better when sung to a polka beat..." "Black hole sun...", for example.
I don't believe that it is. From the cursory second reading of the paper- it's a new type of sensor.
The paper says that the sensor was a Kodak KAF-16802CE. http://www.datasheetarchive.com/KAF-16802CE-datasheet.html#datasheets is the datasheet for this chip, and it appears to be a stock Kodak CCD sensor. Nothing particularly new about it at all. The CE part implies it is a color filtered version.
The new part is the microlens array bolted on the front.
I read the paper linked to elsewhere, which was posted after I commented originally. Fascinating. I still say that the company website is marketing hype and patently false when it implies that it captures all the light rays. They imply this not only when they compare their product to a normal camera (the section I quoted), but later when they use the phrase "full light field" in describing what they process into the final image.
The paper clearly shows that it does not capture any more of the rays than any other camera.
What it does is exchange resolution for information about where each proto-pixel is focusing, either in front of, at, or behind the image plane (microlens array.) And from that it can "refocus" the image.
So, maybe the camera itself is real, but the hype on the website is still hype. I found the "picture gallery" especially unimpressive since the only "change of focus" I saw was when the small images moved to the center. Maybe this has something to do with not having flash on this system, but if you need flash to look at pictures something is horribly wrong. If these pictures are going to be printed, maybe I need to develop "flash paper" to print them on. Excuse me while I go file a patent...
Slashdot Mirror
That still seems problematic to me. If I am being arrested for, say, burglary, why should the cops need access to whatever personal data is on my phone?
If you had an accomplice, it is likely that his name and phone number will be in your phone. Maybe the name and number of your fence. I'd say that there was sufficient probable cause for a warrant to search your phone. After all, they're also going to get a warrant to search your house for stolen property.
Last I checked, even when you get arrested you have some rights (albeit fewer than a free man). So why would the default assumption be that you surrender the right to a private phone when arrested for a crime not involving the phone?
Dunno. Why are you making this assumption? The article talks about preserving potential evidence after an arrest but before the warrant is issued. You'll also lose your wallet and other contents of your pockets when you get booked, why would you think a phone would be exempt?
Ever heard of a time-stamp?
Yep. I also know how to create them when necessary containing any time you'd like in either LTC or VITC format (or burned into the image, if that's how you want it), and know that those time stamps are rarely shown on the news when the video is shown. I also doubt that too many camera phones create them in video they record, but even those that do can be "fixed" in post after editing.
Do you have a point?
With all due respect, officer,
I have no idea who you are talking to here. Certainly not me. But I do understand the qualifier "with all due respect", which is what people who have no respect for the other person say.
I have never seen any citizen-made cop recordings released that had any cut-edits in them, ever.
You don't watch the news much, then. Or you can't recognize cuts when you see them.
All the cop-on-tape stuff I've seen has been uploaded to YouTube as a public service, for free and at personal risk.
Yes, very risky, posting videos on YouTube. And I guess this answers the question of "don't watch the news much".
It's sad that you think that there is no possible way that any YouTube video could have been edited, even as simple an edit as to forget to post the first ten minutes of the cop/citizen interaction. You know, the part where the citizen is actively resisting arrest or doing something else violent, while the cop tries less physical means of dealing with it. You think that the interaction started with the citizen in a choke hold being handcuffed, because obviously the citizen could never have done anything to merit such treatment, and obviously the interaction began at that point in time and could not possibly have started before that.
What you have here is simply evil propaganda
Yes, I'd classify your comments that way. You are honest about your lack of respect for people whose opinion differs from you in this discussion, and honest about your participation. Refreshing.
Secondly, it's pretty bad that they posted the home addresses of a bunch of cops.
Why? Cops should have no expectation of privacy because they are public servants serving the public, and they actually are on-call 24/7, so of course they should expect no privacy in their homes, either.
Maybe this points out the dangers of vigilante hacking? We do it because we can and screw the consequences!
And of course, shouldn't the cops want to be recorded if they're not doing anything wrong? On TV, people being arrested often claim bogus police brutality or some such nonsense. In real life, having a bystander recording the situation could help them.
No, in real life, a recording of the situation will be edited to paint the cops in a bad light. Nobody gains much from releasing a tape of them doing things the right way. There are considerable advantages to selective editing. Like, edit out the abusive drunk throwing a punch or two at the cop, but leave in the cop shoving him up against the car and cuffing him. Sell that to the media, or to the drunk's lawyers who have conveniently filed a police abuse case...
Seems to me any cop that doesn't want themselves to be recorded while performing PUBLIC duties in PUBLIC places isn't confident that they're not going to get in trouble for doing something wrong.
More like they are pretty confident that the people who don't like cops (criminals, for one) will have no problem editing any tape to put the cop in the worst possible light and try to make it look like he did something wrong.
Well, Obama is literally a puppet, a mechatronic puppet; controlled by brainwaves from the fleet of orbiting spacecraft piloted by angels who protect us from the lizards. And....
Much simpler and more nefarious than that. He's receives his control messages from one or more visual cuing devices placed in front of him whenever he appears in public, which contain encoded messages for him to speak at the appropriate times.
Humans, I mean we, call them 'teleprompters'.
You could use USB sticks, external drives and external printers on it.
Yes, I can see merit to USB sticks, but an external drive is going to pull way too much power to have much use. An external printer is going to give you about five minutes of battery life for your tablet.
But for a cellphone? No. Most cellphones ARE the USB stick.
Option 5: Attempt to negotiate with the potential host and if there is no response to negotiations assume you are connected to a dumb charger and consume the power you need, with the caveat that you limit yourself to what the supply can provide.
Standardising on 12V for laptops has the issue that sooner or later someone will get the "bright" idea to connect them directly to car electrics. That means you either have to design the devices to stand being connected to car electrics or you have to deal with the returns that result from idiots conecting an unsuitable power supply (and not admitted they did so of course).
What makes a power source "unsuitable"? Why, the design of the object connected to it, of course.
What makes a car 12V outlet unsuitable for a laptop? Variation of voltage in normal operation might be one thing, but a laptop can be designed to handle it. The sudden loss of power or brownout when starting? Yes, that can be designed around. In fact, a laptop is much better at dealing with this than many other things since a laptop has an internal battery which makes the laptop into a UPS.
So, if 12V becomes the standard, it would be a foolish laptop manufacturer that didn't take automotive electrical systems into account when designing the new power sections. There are so many reasonable apps for 12V powered computers that I'm actually surprised there aren't more of them already.
I've seen DC/DC converters specifically intended for such purposes -- 10-15V input, 12V output. It's not hard, and those converters are not magic.
You have two options:
Option 3: assume that you can take at least 100ma without negotiation and don't discharge completely while trying to negotiate via USB protocols with a dumb charger.
Option 4: start by taking 100ma, then try 150ma, then 200ma, until the port is shut down, then disconnect and allow the port to restore, and then draw the last known current.
See, two more options. Neither one requires smart chargers or special cables with munged data lines so they can't be used as normal USB cables.
The power supply may be perfectly happy putting out 20A but the wires leading to the outlet will have a maximum amperage before the melt. You can't tell that from a voltage drop.
That "melt" comes from heat, which comes from power dissipation, which comes from internal resistance, which causes a voltage drop. It's not rocket science, it is simple physics. While the battery you have connected the wires to may not show any voltage drop, the end of the wires connected to the charger will see it and can act upon it.
Of course, the ten amp fuse in the cigarette lighter plug any properly designed car charger will have will blow a long time before the 15 amp car fuse does, and the charger itself will be able to figure out that it is pulling 9 amps from a circuit that is rated at 10 amps (which is why cigarette lighter plugs have those 10A fuses in the first place) and shut itself down long before either fuse blows.
Then you could just plug your laptop into it's own USB port and you're all set!
That would be cool, I could power my laptop from its own USB port while I am busy copying my mp3s onto itself via USB! It has to work with USB2, though, because the volume of stuff I have to copy is too large and would take longer that one charging cycle otherwise.
Of course, I could always just turn the volume down and get done copying faster. I should have thought of that before.
Most power supplies already have a digital controller inside,
Citation required.
I have opened up a large number of wall-wart style power supplies and have yet to find any "digital controller" inside. The closest to anything digital I've found is in the switch mode supplies that use PWM to regulate.
In the example given above, what if the power supply is overspecced, but is on a 12V 10A fuse (as most/all car cigarette lighters are).
Put in a proper fuse. Or put a simple low value resistor in series.
If you are manufacturing a power supply for car use (i.e., cigarette lighter plug) then put that resistor (or any other current sensing system) INTO THE SUPPLY. Design your supply to limit itself to what you have. In fact, most of the cigarette lighter plugs on inverters or other supplies I have already have a 10A fuse built it, so those devices already know they can't draw more than that. If they do, then it is poor design on their part.
A properly specified power supply will never drop voltage to a point of current insufficiency in its usable range,
And that's why detecting a sag is a means of detecting a supply limitation without having to have the supply and the device both singing three part harmony trying to negotiate whether the supply will sink current or the charged device will source it.
but other pieces of the puzzle may not be up to task.
If you are going to design a standard that will solve the whole world's problems, don't forget there are hungry children in China and AIDS is rampant in Africa.
If you are going to limit your standard, you might as well limit it to something that will solve the problems of the vast majority of users and let the borderline cases be dealt with in other ways. E.g. if you use a car supply designed for a ten amp cigarette lighter socket on a 2A 12V supply, you deserve to get your fuses blown if the charger designer cannot detect a serious overcurrent issue and resolve it. There is no reason to expect a simple 2A 12V supply to have the smarts to negotiate with anything plugged into it for how much current it can draw or if you can put 12V back into the supply.
One thing I need more information, however. The standard industrial DC application uses 24VDC, where is the consumer electronic's 19VDC came from?
I assumed that the now common laptop 19V supply was based on the batteries being used. A voltage high enough that it doesn't need to be boosted to charge the batteries. From that, you can tack on all the other DC/DC converters pretty easily for lower voltages.
Although, someone else has posted that this voltage is based on the voltage for the backlight of the LCD display. I don't know. I don't believe it, since the backlight voltage has to be generated from the battery voltage when portable. If you have to have a circuit to produce that voltage anyway, then you save nothing. You only save if you make the incoming voltage optimized for the battery you have. Charging the battery is about the only thing you do while on shore power that doesn't happen when portable.
With negotiation the laptop can plug in and make a decision about whether or not there's enough power to do anything useful.
Nonsense. You don't need negotiation to determine this. Just watch the input VOLTAGE. If the voltage starts to drop as you pull more current, then the supply is limited and you need to do something about it. That takes NO intelligence in the supply other than the natural current limiting.
All that this negotiation adds is the requirement that you buy someone's smart charger instead of using the power you already have available. You can't hook your 20A 12V power supply up to your laptop to charge it because your laptop will be trying to negotiate with the supply. My 30A supply would power your laptop all day, except the laptop will shut itself off when it can't negotiate with my power supply. Nor would my bank of backup batteries be able to run that laptop, for the same reason. No, I would be forced to buy someone's smart charger and probably do a wasteful conversion of my 12V into 120AC just so I can plug the smart charger in somewhere.
Having your laptop decide what not to do based on the power supply it is plugged into is a different problem than finding out that the cellphone you just bought won't use any of the chargers you already own because it wants 6V and your chargers only do 5V, and it has a microUSB connector and your chargers are all mini-USB. And then finding out that the ebook you just bought, even though it claims to charge through the USB connector, won't charge unless it is connected directly to a host (a hub isn't good enough).
The latter problem doesn't need smarts, it only needs a standard voltage and connector. If I want to home-brew a charger for my phone based on the bank of solar-charged batteries I have, all I should have to do is get one of the right connectors and produce the right voltage. I shouldn't have to program some computer chip with the right protocols to negotiate what can be mandated by fiat.
Solving this problem with the same solution that you want for your laptop is vast overkill and will cost everyone else a lot of money they shouldn't have to spend.
The device needs communication to negotiate between the power adapter and the device to be powered. The device and power supply will communicate things like if it sourcing or sinking current (or capable of doing both), whether it is a battery, an intermittent supply like wind or solar, etc. It sounds pretty cool if manufacturers go along with it.
There's cool and then there is practical.
A cell phone isn't going to source power to anything. My PDA isn't going to source power to anything. My camera isn't going to source power to anything. My cell phone charger isn't going to sink power from anything. My computer isn't going to source power to anything (via the charging jack). It isn't going to sink power from anything (on the USB ports). My computer charger isn't going to sink power from anything except the mains, and if you build that charger with the same plug for the mains that you use for the device, you are stupid.
The problem is not that the devices we have are not smart enough, it is that the number of different voltages they were designed to source or sink is too large, and the number of different kinds of connectors is too high.
Laptops, in particular, already have the DC/DC conversion hardware built in to provide the internal voltages, and there is no reason that they cannot be built to accept a range of input voltages from 12 to 19 instead of frying themselves if you put 18.2V into an 18V connection. The same concepts that allow the now ubiquitous 100-250VAC wall warts would allow laptops to have a wide range of input voltages.
The only thing this complexity is good for is making an industry around supplying smart charging devices that they can charge extra for because they are smart, and shutting out small companies who want to fill niche markets but cannot afford the cost of a fullblown smart charging device, or private individuals who want to build their own.
Yes, a full-blown USB connection needs to have a smart communication system so the devices can tell the host what they are and etc. No, a device built to charge through a USB connection doesn't need to communicate shit, all it needs to do is see 5V on the input and assume that it is connected to something that will limit the current it will provide if necessary. That means you can use any 5V supply to charge it, whether that is a laptop, a battery, or a wind turbine.
Please stop this headlong rush into "cool" and settle for practical. These supposed requirements for communications really aren't necessary, at least not for the vast majority of charger/device issues. At the base level, a charger supplies a specific voltage and up to a certain current; any current draw over the limit can be detected by the device and it can either back off or the charger will shut off. Make that voltage a standard, and use a common connector, and the vast majority of issues go POOF! If there truly are border cases that demand this level of intelligence in devices and chargers, then apply those higher standards to THOSE DEVICES, but make the manufacturer justify it so they can't just claim "special case, you need to buy my special overpriced charger" like Sony does for their eReaders. If a laptop manufacturer says "we can't design a laptop that will take 19V input, so we need to have a special case 15.8V charger for it", they should be laughed out of the marketplace, not allowed to profit from stupidity.
Ever plug a GPS into a smartphone with USB? Usually the GPS says to itself "Oh look, a connection. I'll just charge up my battery...".
Why would your smartphone even try to put 5V onto the USB connection? Not very smart, I'd say. It shouldn't be acting as a host in that respect no matter what, given the battery capacity.
Example: some Sony phones use the micro-USB connector to charge. (I don't know which models, I just know that there are "Sony chargers" that have this connector.) The Sony eReader uses the same connector.
The Sony phones apparently don't care if they are connected to a computer, they'll take power from the connector. The eReader DEMANDS that the USB host negotiate power requirements or it will happily discharge itself waiting to talk to the USB host. OR you put the appropriate shorts/loads on the data lines that tell it to charge anyway.
I got a pair of Sony "chargers" for Christmas so I could charge my eReader while travelling without a computer. No joy. "I'll just open up the charger and short the data lines to confuse the reader into charging" I thought. Also no joy. The Sony charger manufacturer saved money on the cable and used a two-wire cable. No data lines at all.
A better solution to the problem is to define a standard voltage that devices will accept for charging/operation. That's all. "Put 19V on the DC input, you get charging." For low power devices, "put 5.2V (USB) on the USB power lines".
Whatever provides the voltage is responsible for limiting the current to what it can provide. End of problem. But this "send a voltage request and ack and nak and then toggle this data line to 43 ohms and then draw 3 mA on the other data line and then look for a ..." is just crap. Devices with a micro/mini/regular USB connector charge when 5V is applied. Devices with a standard XYZ connector take 19V. (Better would be 12V, but one standard at 19V is better than no standard at all).
You might want to look up "light field"; apparently it's a well-defined term within the field (which has some connections to what I'm familiar with and hence was talking about but is formulated differently for different application). In particular, "full light field" is different from "all the light rays".
I'm using the definition that Lytro has on their website, which I quoted in my first comment. Again:
Emphasis mine. Wikipedia's definition is essentially the same. The "all the light rays" bit is a natural result of saying "every direction through every point in space". The word "full" does not appear on that Wikipedia page, so I have to assume that it has the standard english meaning of "complete" or "all". If the "light field" is "all the rays", then the "full light field" cannot be a subset, it must, too, be "all the rays".
Measuring the full light field means measuring all the available information (in a different context you may be familiar with, if you work with light in any way, an analog would be a full Stokes polarimeter that measures all available polarization parameters of the light, not just one or two, as most cameras and filters do) in the light that the sensor receives,
So again, the claim that they are processing "the full light field" is misleading. They certainly are not processing all the available information, since clearly they aren't including polarization information (which they don't capture at all), even if you assume that "full light field" truly is not "the amount of light travelling in every direction..." as they define it.
I'll admit first that I myself wasn't familiar with the term "light field" and the term itself did sound a little sci-fi-y, but it is a valid, technical jargon, not just marketing speak or jibberish you see in sci-fi.
I had no problem with the term "light field", only with combination of the way they defined it and then the claim they were processing the "full light field", along with the implication that they were capturing more rays than a "conventional camera". That, and a lot of the other stuff on their pages like "You are a beautiful, unique snowflake." and "No more flat, boring, static photographs." (The "living pictures" certainly look flat and boring and static to me, so yes, there still are "flat, boring, static" photos available from their system, and unless places like Facebook and other photo sharing sites adopt the code to allow fancy adjustable focus pix most of the photos shared on the web will be flat and static, too. Boring is not well defined, so I'll not deal with that claim.)
You can't simultaneously not believe that they are claiming to construct a full 3D model and also believe that they are claiming to capture "all the light rays":
Yes, I can, because "constructing a 3D model" is what may or may not be done after processing the "full light field", which THEY define as all the rays passing through an object.
And "discarded" and "never measured" is the same thing, too.
Nonsense. "Discarding" information means you have something and gotten rid of it. "Never measured" means you didn't have that information to start with. Whatever information you did not measure from the photon is NOT MEASURED, it is not information that you are discarding. Otherwise you could simply NOT DISCARD it and you would still have it.
But that is an issue of syntax not really relevant to this discussion. The important part is that the website is filled with marketing-speak which is misleading, whether you think you can discard that which you didn't have to begin with or not. The "full light field" is not processed simply because they don't capture the "full light field"; whatever processing that could be done following that caputure is irrelevant.
I don't think they are claiming to build a full 3D model of the subject (that would indeed be sci-fi).
I don't think they are claiming that, either.
I do think they are claiming to use additional information usually discarded by conventional light sensors (i.e. CCD),
Not "discarded", it is never measured.
i.e. something that corresponds to the radius of curvature
No. It deals with the position of the focus, either in front of, on, or behind the image plane, which is the microlens array. Focus in front of the array and the resulting image on the sensor is either normal or reversed, I forget which. Behind does the opposite.
but the paper abstract talks about light rays, like the rays in geometric optics).
My comment was about the company website, which talks about "all the light rays", implying that it catches light rays that normal cameras do not. They don't catch any more than any other camera, they just don't use one pixel to detect one pixel's worth of them, they us a lot more. That gives them "direction" information.
What I am continually amazed by is just how large a range he and his band have. They do tons of different styles when parodying songs and do them extremely well.
I have lost count of the times I've been listening to a radio station and heard what I thought was a Weird Al song playing, then thinking "those aren't the right words", only to realize I was hearing the original artist doing their less-than-impressive original version.
And hearing an original song and thinking "that sounds so much better when sung to a polka beat..." "Black hole sun ...", for example.
Transparent sensors. Every picture is a 3d array instead of a 2d array.
Foveon
I don't believe that it is. From the cursory second reading of the paper- it's a new type of sensor.
The paper says that the sensor was a Kodak KAF-16802CE. http://www.datasheetarchive.com/KAF-16802CE-datasheet.html#datasheets is the datasheet for this chip, and it appears to be a stock Kodak CCD sensor. Nothing particularly new about it at all. The CE part implies it is a color filtered version.
The new part is the microlens array bolted on the front.
The paper clearly shows that it does not capture any more of the rays than any other camera. What it does is exchange resolution for information about where each proto-pixel is focusing, either in front of, at, or behind the image plane (microlens array.) And from that it can "refocus" the image.
So, maybe the camera itself is real, but the hype on the website is still hype. I found the "picture gallery" especially unimpressive since the only "change of focus" I saw was when the small images moved to the center. Maybe this has something to do with not having flash on this system, but if you need flash to look at pictures something is horribly wrong. If these pictures are going to be printed, maybe I need to develop "flash paper" to print them on. Excuse me while I go file a patent...