Red has a wavelength thats more like 550-650nm or something like that...
I don't agree. Colours are psychological phenomena, not physical. What we perceive to be red does not only depend on the wavelengths emitted by an object, but also on things like lighting conditions, colours of surrounding objects, and patterns. It's nonsense to say that "the colour red" has a wavelength.
But we can objectively test for that and it has been done. If I show people a chart with various shades of red, there is one or a very small group of very similar shades which people all over the world will identify as "the most red". The same thing can be done with blue and green although for green, people will identify two different shades because there are two phenotypes for the green receptor.
Now do the same test using monochromatic light sources and you can identify which wavelengths are the "most" red, blue and green.
When was the last time we heard about a new tech breakthrough that wasn't followed up with "5 to 10 years"...Though it might be 5 years by the time the price drops enough for the avg consumer.
The first hard drive using a read head based on giant magneto-resistance was commercially released about 10 years after the effect was discovered.
Also, power steering is totally worthless while the car is moving at anything more than a crawl. Power steering is for parking lots, and not much else. It takes very little effort to turn the wheels when they are already rolling.
This depends on the specific design of the vehicle. I have tested the brakes and steering of my GMC Sonoma with the engine off and it becomes almost undrivable no matter what the speed is. The steering becomes stiffer than my old Pinto without power steering when stopped and after the brake vacuum reserve is exhausted (two pumps at most), you literally have to stand on the brake petal pushing yourself out of the seat.
One that can be operated with winter gloves on or such.... He's also going to want something that is probably water proof, drop proof and has a battery life much longer than that of an old phone.
The gloves issue came up for me this past winter when I did not have to remove them in negative F weather. I would add AA battery support to your list. The new low discharge NiMH cells work great.
My old Garmin GPSMAP 76s and 76csx both work with or without gloves, are water resistant, operate for about 24 hours on 2 x AAs, float on water if dropped, are not performance compromised by small aperture antennas, and rely on no outside service availability except for the GPS broadcast itself.
With a pair of alkaline or lithium AAs, you could put one away for years and expect it to work without hassles when needed.
A single optical stream is much easier to use, sort of like the communications equivalent of Amdahl's Law.
She only made one law? I thought she was a queen. Kind of cool though that real-life tech is starting to take advantage of laws that before belonged only to the realm of science fiction.;)
She made lots of laws but only had enough time to write one of them down.
The biggest problem with what happened is something that wasn't even mentioned in the summary: they kept three of his cell phones for no apparent reason. The article only presents one side of the story, but assuming it is accurate, this is unjust. They shouldn't keep objects without a reason.
I wondered about this also. It would be an easy way to intercept calls made to him on phones that they did not previously know about.
In contrast it sounds like in your case it cost you an hour in the afternoon sun. So while you say there's nothing ever to be gained by playing the game (in this case just saying you're a citizen), I personally value not spending an hour in the sun. (Though I wouldn't have let them search my trunk if they asked either).
The difference being then he would have spent an hour in the sun, provided incriminating statements, and maybe fallen into a perjury trap. Cooperation does not preclude being screwed over when they have already made up their mind.
An offer by law enforcement to not inconvenience you is not consideration and they can break it at will without penalty. They might as well offer to not break your arm.
1. What do you think the US government's encryption-breaking capability REALLY is these days? e.g. for example, are common encryption protocols and key-lengths used in, say, online banking and e-commerce readily crackable by the Feds?
Banking is not a good example since financial records are already subject to government disclosure.
The government (and NSA) have no monopoly of cryptographic talent. Many currently used 64 bit and larger cyphers are almost certainly secure.
2. Do security agencies of the federal government automatically flag for further investigation all people who use "an excess amount of encrypted traffic"?
I have no idea. The government certainly does not go out of its way to encourage opportunistic encryption. IPv6 has the potential to quash routine surveillance making the issue moot.
If as a result of ubiquitous surveillance opportunistic encryption takes off, they will really have screwed over their ability to execute legitimate search warrants for electronic communications.
3. Does the FBI, a "domestic" intelligence agency, have the right to spy on foreign residents whose net transactions traverse the US border? If they don't have the right, are they doing it anyway, or is that some other agency?
There is a border exception to 4th amendment search protections. I figure all telecommunications crossing the border is monitored whether they admit it or not.
If you can prove that carbon creates externalities, and you can find a very good estimate for the value of those externalities, then you can impliment a Pigovian tax which would be economically efficient (which is what free marketers usually get excited about).
Viewers are grass in the pasture, and each web site operator is a herder, and the cows are the types of ads they have on their web site. Many will try to get more and bigger cows (more ads and more annoying ads), until it is no longer sustainable and the pasture dies (people no longer view ads because everyone has an ad blocker).
Since I use an ad blocker and a tar pit, I am more like a triffid than a clump of grass.
I have been waiting to use this quote in a Slashdot reply:
Professor Bernard Quatermass: The will to survive is an odd phenomenon. Roney, if we found out our own world was doomed, say by climatic changes, what would we do about it? Dr. Mathew Roney: Nothing, just go on squabbling like usual. Professor Bernard Quatermass: Yes, but what if we weren't men?
You can tack against the photons allowing one to lower, raise, or change your orbit. Out takes you back, in takes you forward (can't do this one), forward takes you out, and back takes you in.
1) brakes are always stronger than the engine. There is no car in the world that will not stop when braked, even if the accelerator is held full down. It's a basic safety requirement.
There are several reasons braking power can be insufficient to overcome engine power. Assuming everything is operating properly, overheating the brakes can cause loss of braking power. Even worse, if the engine throttle is wide open, the vacuum reservoir can be exhausted by pumping the brakes leading to loss of power assist. I wonder if ABS makes this worse because on my relatively new light truck, the brakes are so stiff without power assist that it is difficult to even stop on a gentle incline. I have to literally stand on the brake in that case to stop.
This does make it triangulation, as based upon the frequency which you are using to talk to to the cell tower, that gives you your direction (Roughly).
Aren't they using beam forming in dense areas now and for more range? That would narrow the sector size down considerably.
Your signal stregnth then gives you (vague) distance,
Really vague. It is one thing for the base station to adjust the mobile transmitter power in a relative way but another to rely on some type of absolute calibration even without path loss variations. 6 db change is a factor of 2 difference in distance so even a minor calibration error would make for poor accuracy except where the cells are small and in that case, lots of towers will be available for TDoA or triangulation anyway.
doing this between more cells gives you your location.
Which is easy in areas where extra cells are available because of subscriber density but that can not be counted outside of that.
But who knows, maybe there are those out there would really want the pants and suspenders approach to location, I wonder if there is a provider who offers both?
The GPS (or AGPS in this case) part is pretty cheap or even free to implement since it has other applications paying for it as well. The base station technologies require infrastructure upgrades and have more limited uses.
I have to admit though that I have never considered GPS on PDA or phone to be particularly useful except for E911. The only time I would really need it is when the phone system is down in which case I would not expect it to work anyway. I just carry an old dedicated mapping GPS receiver. Without a touch screen, it even works in cold weather when gloves are worn.:)
Also, some cell companies (such as AT&T) use the technology you mention, others do not have the capacity and instead use GPS. They were given the option, and they went various ways. Both have drawbacks: what if GPS doesn't have a signal? OR: What if you can only see one or two towers?
I always saw the early E911 location requirements as a bunch of bureaucratic wishful thinking and I guess a lot of phone companies had the same response since they have been suing the FCC over it. GPS reliability when indoors or under cover is poor enough with even dedicated receivers that I always figured a hybrid system would be necessary if only because phone ergonomics compromise GPS antenna design.
As far as the E911 GPS location requirements, the FCC would have been better off with a real world empirical benchmark. Then they would have discovered what they were asking for did not exist when they could not duplicate it.
The GPS is a completely separate unit and is usually offline to save power.
Assisted GPS solves the GPS power problem in cell phones and mobile devices. When a fix is required, the cell tower sends the current GPS state information (almanac, ephemeris, and time) so the that GPS receiver can start hot and begin generating position reports immediately.
I remember seeing a GPS receiver for time keeping applications that had the RS-232 start bit synchronized with the PPS signal so only two wires were needed. Implementation wise either the UART clock would need to be phase locked to the PPS or TXD could be delayed for a fraction of a bit length between the UART and level shifter.
I am not sanguine that electric vehicles produced by multiple competing manufacturers (or even just a single manufacturer like GMC) will not result in multiple incompatible charging standards or even worse, DRM limited charging.
I only recently read an article about a MMIC (microwave monolithic integrated circuit) tuner which used large area silicon dioxide capacitors and GaAs switches to implement antenna tuning in the current cell phone bands. I actually built a manually operated antenna tuner for 2 meters but I cheated. It was more of a heavy duty adjustable gamma match made from silver soldered brass rod and tubing which you could wire tie to whatever antenna structure you wanted to use. It looked like a very small trombone and worked fabulously well for using things like power transmission towers or chain link fencing as an antenna but of course you did not gain any control over the radiation pattern and power loss into the earth was significant.
I suspect an antenna tuner with impedance matching at microwave frequencies could be built using a series of open and shorted stubs switched using 1/4 wave transmission lines and PIN diodes but it would take up too much space to use in a small handset unless it was done as a multilayer circuit board with the stubs on the inside between two ground planes.
As for sampling front ends: they don't really cut it due to parasitics -- they can be fast, but they aren't really accurate -- 12 bits of performance would be pushing it I think. Surely if you would be very clever and do, say, FEM of an integrated sampling bridge, and would characterize well all the parasitics and how they can be balanced out, it could probably be done. But using off-the-shelf parts with nothing exotic: I will believe it when I see it done.
I am not sure they even got 8 bits worth of performance. Once you get into that realm, sample and holds are more like sample and slow downs.:)
The only practical way I know of is with a fast variable gain amp to blank overdrive -- this can readily be done, and this way you can test settling of 18 bit DAC's, and it's really no big deal once you try it and get it working. It doesn't cost much, either.
I'm playing with a blanking front-end that uses JW's variable transconductance amp approach, gated with fast comparators, and so far I've got it to recover within 100ns to 12 bits -- that's on the first try, on a real crappy breadboard. It's still far away from 10ns one expects the recovery to be in a 100MHz scope, but I should be able to cut it down to 25ns or so without doing anything extraordinary. And I don't really have all that much analog tinkering experience. Surely someone who knows what they are doing could get it to work way better and cheaper.
Hehe. You read that application note also?
Non-saturated switching is always going to have an advantage over saturated switching but unless you can control the parasitics you are doomed. The big improvement now has been monolithic variable gain amplifiers with good DC and settling performance. I suspect they got that by using the same techniques which were applied to operation amplifiers to prevent thermal gradients generated by the other stages from unbalancing the input stage differential pair. You could probably do something similar using dual and quad matched transistor arrays to build a Gilbert cell multiplier but it would be complicated and likely not as fast and I suspect parasitics would be a problem. Does anybody make or sell cross coupled quad transistor arrays or something equivalent? Linear Integrated Systems sells matched duals and they might be enough. If you use discrete duals then you do not have to worry about thermal feedback from other stages anyway.
As far as construction goes, dead bug construction over a ground plane is probably going to be mandatory for good performance. If you can go the printed circuit board route, you would still need a good ground plane. I tend to use double sided copper board for a ground plane and shielding and will build an entire small enclosure if necessary. I have even built a couple of rugged helical resonators that way. Kynar insulated wire wrap wire (the whole color table is available) or just enameled copper works well for hook up wire if you include strain reliefs. If you have a precision shear (or a good tabletop sander and time), you can even make little microstrip transmission lines to be soldered or glued down onto the ground plane.
For an oscilloscope to be a truely universal instrument, it should have a minimum number of caveats. Poor signal fidelity (measured in single % - gimme a break), poor overload recovery, no antialiasing protection on many DSOs, ridiculous trigger holdoff times (orders of magnitude worse than on a $100 tek 7K mainframe from the 70s) -- those are the gripes I have with current technology.
Luckily the stuff that used to be out of reach financially is now either affordable or free: you can easily get a dev board with fast FPGA with multipliers on it, 64MB of DDR2 and a USB 2.0 connection for $200 IIRC. The software to do logic de
Slashdot Mirror
But we can objectively test for that and it has been done. If I show people a chart with various shades of red, there is one or a very small group of very similar shades which people all over the world will identify as "the most red". The same thing can be done with blue and green although for green, people will identify two different shades because there are two phenotypes for the green receptor.
Now do the same test using monochromatic light sources and you can identify which wavelengths are the "most" red, blue and green.
The first hard drive using a read head based on giant magneto-resistance was commercially released about 10 years after the effect was discovered.
This depends on the specific design of the vehicle. I have tested the brakes and steering of my GMC Sonoma with the engine off and it becomes almost undrivable no matter what the speed is. The steering becomes stiffer than my old Pinto without power steering when stopped and after the brake vacuum reserve is exhausted (two pumps at most), you literally have to stand on the brake petal pushing yourself out of the seat.
The gloves issue came up for me this past winter when I did not have to remove them in negative F weather. I would add AA battery support to your list. The new low discharge NiMH cells work great.
My old Garmin GPSMAP 76s and 76csx both work with or without gloves, are water resistant, operate for about 24 hours on 2 x AAs, float on water if dropped, are not performance compromised by small aperture antennas, and rely on no outside service availability except for the GPS broadcast itself.
With a pair of alkaline or lithium AAs, you could put one away for years and expect it to work without hassles when needed.
Then to hell with him!
She made lots of laws but only had enough time to write one of them down.
I wondered about this also. It would be an easy way to intercept calls made to him on phones that they did not previously know about.
The difference being then he would have spent an hour in the sun, provided incriminating statements, and maybe fallen into a perjury trap. Cooperation does not preclude being screwed over when they have already made up their mind.
An offer by law enforcement to not inconvenience you is not consideration and they can break it at will without penalty. They might as well offer to not break your arm.
Banking is not a good example since financial records are already subject to government disclosure.
The government (and NSA) have no monopoly of cryptographic talent. Many currently used 64 bit and larger cyphers are almost certainly secure.
I have no idea. The government certainly does not go out of its way to encourage opportunistic encryption. IPv6 has the potential to quash routine surveillance making the issue moot.
If as a result of ubiquitous surveillance opportunistic encryption takes off, they will really have screwed over their ability to execute legitimate search warrants for electronic communications.
There is a border exception to 4th amendment search protections. I figure all telecommunications crossing the border is monitored whether they admit it or not.
What is in it for the politicians?
Since I use an ad blocker and a tar pit, I am more like a triffid than a clump of grass.
I have been waiting to use this quote in a Slashdot reply:
Professor Bernard Quatermass: The will to survive is an odd phenomenon. Roney, if we found out our own world was doomed, say by climatic changes, what would we do about it?
Dr. Mathew Roney: Nothing, just go on squabbling like usual.
Professor Bernard Quatermass: Yes, but what if we weren't men?
http://www.imdb.com/title/tt0062168/
You can tack against the photons allowing one to lower, raise, or change your orbit. Out takes you back, in takes you forward (can't do this one), forward takes you out, and back takes you in.
There are several reasons braking power can be insufficient to overcome engine power. Assuming everything is operating properly, overheating the brakes can cause loss of braking power. Even worse, if the engine throttle is wide open, the vacuum reservoir can be exhausted by pumping the brakes leading to loss of power assist. I wonder if ABS makes this worse because on my relatively new light truck, the brakes are so stiff without power assist that it is difficult to even stop on a gentle incline. I have to literally stand on the brake in that case to stop.
Aren't they using beam forming in dense areas now and for more range? That would narrow the sector size down considerably.
Really vague. It is one thing for the base station to adjust the mobile transmitter power in a relative way but another to rely on some type of absolute calibration even without path loss variations. 6 db change is a factor of 2 difference in distance so even a minor calibration error would make for poor accuracy except where the cells are small and in that case, lots of towers will be available for TDoA or triangulation anyway.
Which is easy in areas where extra cells are available because of subscriber density but that can not be counted outside of that.
The GPS (or AGPS in this case) part is pretty cheap or even free to implement since it has other applications paying for it as well. The base station technologies require infrastructure upgrades and have more limited uses.
I have to admit though that I have never considered GPS on PDA or phone to be particularly useful except for E911. The only time I would really need it is when the phone system is down in which case I would not expect it to work anyway. I just carry an old dedicated mapping GPS receiver. Without a touch screen, it even works in cold weather when gloves are worn. :)
I always saw the early E911 location requirements as a bunch of bureaucratic wishful thinking and I guess a lot of phone companies had the same response since they have been suing the FCC over it. GPS reliability when indoors or under cover is poor enough with even dedicated receivers that I always figured a hybrid system would be necessary if only because phone ergonomics compromise GPS antenna design.
As far as the E911 GPS location requirements, the FCC would have been better off with a real world empirical benchmark. Then they would have discovered what they were asking for did not exist when they could not duplicate it.
Assisted GPS solves the GPS power problem in cell phones and mobile devices. When a fix is required, the cell tower sends the current GPS state information (almanac, ephemeris, and time) so the that GPS receiver can start hot and begin generating position reports immediately.
I remember seeing a GPS receiver for time keeping applications that had the RS-232 start bit synchronized with the PPS signal so only two wires were needed. Implementation wise either the UART clock would need to be phase locked to the PPS or TXD could be delayed for a fraction of a bit length between the UART and level shifter.
I am not sanguine that electric vehicles produced by multiple competing manufacturers (or even just a single manufacturer like GMC) will not result in multiple incompatible charging standards or even worse, DRM limited charging.
Third party charging is theft!
Only if we're talking about the big Corellian ships now and mot the local bulk cruisers.
I thought Johnny Sako and his Flying Robot held up better than Space 1999.
I only recently read an article about a MMIC (microwave monolithic integrated circuit) tuner which used large area silicon dioxide capacitors and GaAs switches to implement antenna tuning in the current cell phone bands. I actually built a manually operated antenna tuner for 2 meters but I cheated. It was more of a heavy duty adjustable gamma match made from silver soldered brass rod and tubing which you could wire tie to whatever antenna structure you wanted to use. It looked like a very small trombone and worked fabulously well for using things like power transmission towers or chain link fencing as an antenna but of course you did not gain any control over the radiation pattern and power loss into the earth was significant.
I suspect an antenna tuner with impedance matching at microwave frequencies could be built using a series of open and shorted stubs switched using 1/4 wave transmission lines and PIN diodes but it would take up too much space to use in a small handset unless it was done as a multilayer circuit board with the stubs on the inside between two ground planes.
5 volts at about 1/2 amp is typical.
I am not sure they even got 8 bits worth of performance. Once you get into that realm, sample and holds are more like sample and slow downs. :)
Hehe. You read that application note also?
Non-saturated switching is always going to have an advantage over saturated switching but unless you can control the parasitics you are doomed. The big improvement now has been monolithic variable gain amplifiers with good DC and settling performance. I suspect they got that by using the same techniques which were applied to operation amplifiers to prevent thermal gradients generated by the other stages from unbalancing the input stage differential pair. You could probably do something similar using dual and quad matched transistor arrays to build a Gilbert cell multiplier but it would be complicated and likely not as fast and I suspect parasitics would be a problem. Does anybody make or sell cross coupled quad transistor arrays or something equivalent? Linear Integrated Systems sells matched duals and they might be enough. If you use discrete duals then you do not have to worry about thermal feedback from other stages anyway.
As far as construction goes, dead bug construction over a ground plane is probably going to be mandatory for good performance. If you can go the printed circuit board route, you would still need a good ground plane. I tend to use double sided copper board for a ground plane and shielding and will build an entire small enclosure if necessary. I have even built a couple of rugged helical resonators that way. Kynar insulated wire wrap wire (the whole color table is available) or just enameled copper works well for hook up wire if you include strain reliefs. If you have a precision shear (or a good tabletop sander and time), you can even make little microstrip transmission lines to be soldered or glued down onto the ground plane.
http://qwiki.stanford.edu/wiki/High_Frequency_Op_Amp_Circuits