The work reported here is certainly interesting, but I simply cannot agree that it opens up a whole new area of previously unused spectrum. Let me explain why.
The bottom line is that there is a fundamental limit to how much data can pass through a given amount of radio spectrum in a given period of time. Let's say you have 100 MHz of bandwidth available and 100 signal sources each generating enough data to fill 1 MHz of bandwidth. Now, we can divy up the spectrum in several different ways.
The obvious one is to place each source on a different frequency and since each one is 1 MHz wide we can just fit them all in. This is called frequency division multiplexing and its how FM radio works.
Next, we could get each signal to buffer 1 second of data and then transmit it at 100 times normal speed for 1/100th of a second. Increasing the data rate increases the bandwidth so each signal is now 100 MHz wide and uses the entire available spectrum, but if we get them to transmit one after the other we get 100 bursts each 1/100th second long and once again the channel is full. This is called time division multi access (TDMA) and it is how your GSM cellphone works.
Lastly, we can take each signal and mix it with a very high speed pseudo random data stream. The signal gets much wider, but the energy per unit bandwidth goes down. At the other end the received signal is mixed with the same random stream and the original signal re-appears. The maths is complex, but it turns out that if I spread each signal out to fill the 100 MHz then I can just about get them all in without them interfering with each other too much. This is called code division multiple access (CDMA) and is how GPS and 3rd generation cellphones work.
Now for the important bit. As you can see, we have 3 different ways to get 100 signals into out 100 MHz of bandwidth. We can choose any one of them, but we can't choose all three. If our 100MHz is already full of TDMA signals and we put 100 CDMA signals in the same spectrum then they will interfere.
Now, if I have a bandwidth which isn't being fully utilised (suppose for example I have only 10 frequency multilexed signals in my 100 MHz) then I can slip in a few CDMA signals and all will be well, but only a few. If I bung 50 in then the FM signals will start to suffer interference.
What Mr Fullerton has done is basically produced a modified version of CDMA which is spread over a very wide band. The radio spectrum is still not used very efficiently, so there is enough room over that huge bandwidth for quite a few of his transmitters to be fitted in. Provided that their average power is low and there not too close to your receiver. But you don't get something for nothing. He's not using new spectrum, just old spectrum in a different way. We could achieve exactly the same effect by taking conventional CDMA and just making the random bit stream much faster.
Finally, there are costs to his approach which is related to the huge bandwidth and that is making an effecient wideband antenna. As someone who designs antennas for a living I can tell you that making a wideband antenna which is efficient means sacrificing gain or size or both.
I congratulate RedHat for their efforts. But as the article says we realy need a trade body if we want to have influence. Consider the following examples:
Linux advocate- Hello, I'm from RedHat Inc.
Law maker- Who?
Linux advocate- Hello, I'm from the Linux Industry Consortium. Our members include IBM, HP, Sun and RedHat.
Law maker- Hello. Pleased to meet you. Would you like a coffee?
Such a group would be able to excert pressure in other areas. For example, whilst Andre Hedrik's effort in the IDE standards committee are greatly appreciated, he has himself said that his influence is limited since he is just a lone consultant and can't officialy represent Linux.
I agree that creating such a body is going to produce numerous problems such as keeping it small enough to be responsive whilst not excluding people who feel they should be represented, and defining its role closely enough to prevent it from influencing things like kernel development. I also accept that we already have groups like FSF and Linux International, but if RedHat are having to go and lobby lawmakers then these groups clearly don't have the required clout. Obviously they could be members of the "Linux Industry Consortium" (I am sure we could find a better name).
...but once ordered to keep logs (and to keep your mouth shut about it), you have to do so or face the music
How do we know that this hasn't happened already? Perhaps all US bases anonymizers have already been served with such orders (perhaps months ago). How would we know?
Are there any good anonymizers in other countries. I don't mind paying for one if it has a reasonable chance of being secure.
Thought: Would it be possible to construct some sort of mutual peer-to-peer anonymizer system. I'm thinking of something a little like FreeNet.
1) The MPAA isn't going after the users, its going after their ISP. A user who is falsely accused has an interest in defending the case, but their ISP doesn't and isn't likely to be interested in claims of innocence from their customer. After all, is that customer going to take their custom else where? How many people have a choice of broadband access providers?
2) It is my understanding (and I have read posts from those claiming to be lawyers which confirm this) that an innocent individual sued by someone like the MPAA has no choice but to comply, since they could never afford to defend the case.
Summary: I have no problem with copyright owners going after those who trade illegal copies provided that those who may be falsely accused have recourse to effective legal protection.
Bob: But IP's can be spoofed. Meet my expert witness...
Do I understand that in this example Bob is a millionair Gnutella user? How else can he afford to defend a case against the MPAA to the point of being able to present expert witnesses?
I design experimental aircraft antennas for a living and have looked at this sort of problem before. My experience of flight certification is limited to the UK military, but regulatory authorities tend to be even tougher on commercial aircraft.
Is this 2.4 GHz kit approved for aircraft use? If so then you have found a bargain. Does the $1200 include the cost of installing it? Where does the antenna go?
However, I have a horrible suspicion that you think that you can just take a commercial 2.4 GHz video transmitter and "put it on an aircraft". Have you any idea how much it would cost to get FAA approval for this (assuming they would allow it at all)? If we were talking a light aircraft with just you and your buddy on board then you might get away with it (or at least avoid a prison sentence if caught). But you are proposing to do it with fare paying passengers!!
Your biggest problem (well one of them) is going to be the antenna. Where are you going to put it, remembering that it needs to basically point down? If you fix it to the outside of the aircraft then that is an external modification which requires the approval of the design authority (usualy the plane's manufacturer). You need to prove to the FAA that it won't effect the aerodynamics. Obviously a small antenna won't but you need a official letter saying so and they cost a lots of money (thousands). You might be able to come up with some scheme involving a small patch which you can push out through the door (maybe!). If we weren't a government agency we could design such an installation for you. It wouldn't cost less than $4000. And as for the loony in another post who suggested fixing it on with sticky tape, well words fail me! What happens when it comes loose and the cable wraps itself round the tail? Well, at least some of those on board will have parachutes!!
Next, if the 2.4 GHz transmitter isn't type approved for flight use then you need it tested for EMC. Its not enough to say "nothing else on the aircraft uses 2.4 GHz". How do you KNOW that it doesn't produce some small spurious signals on a frequency which you do use? Again, this is going to cost thousands.
Remember, you can get away with quite a lot on small private aircraft and those with special experimental licenses (by which you can become your own design authority), but once you start carrying the paying public the rules get much tougher!!
Uh, what about the Edict of Expulsion of all Jews from England in 1290? There has been plenty of totalitarian government in Britain
Sheesh! The man didn't say there had been no totalitarian government. He said that we didn't have any experience of such government. How many people do you know who can remember back to 1290!!!!!!
This topic seems to be rapidly filling up with racist rants from Americans who don't seem to have visited England and English folk who know nothing about America. None of which is "News for Nerds" or "Stuff that matters". So let's get to the NUB!
What can we nerds do to reduce our exposure to this problem?
To take my own case:
Mobile phone - Don't own one.
Groceries - No loyalty card. Pay with cash.
Email - I'd like to encrypt it, but I need to persuade my non-technical friends to also do so. Experiences?
Web - There are lots of anonymisers around. Are they any good? Is it worth paying for one?
So come one guys. Get a grip and address the real technical issues!
Oh, and regarding the USA and UK? All I can say is that if I could learn the language I'd move to Finland and go dogsledding every weekend:-)
Mr Seifried may well be right when he says that checking the GPG signature is not totally secure, but I am sure that it is better then nothing. However, I never check the signature on any of the RPMs I download because I can't figure out how. I have read the "PGP SIGNATURES" section in the RPM man page but it doesn't make any sense to me. I would love to implement the fix in the security portal advisory refered to, but I can't understand it.
What I (and many other idiots) need is a step by step idiot's guide to getting RPM signature verification working. Someone must have written such a thing, does anyone know where to find it? It won't allow me to achieve the supreme security level advocated by Mr Seifried, but I will be much better off than I am now.
Ah well, now I've read the CNET article it doesn't look so bad after all.
As I understand it, the advertisers don't want their adds streamed since they will then have to pay more to the actors in the ads. So, the broadcasters are going to remove the problem ads from the online broadcasts. Therefore, those who listen online could end up with fewer ads:-)
Mind you, I'm in the UK and listen to BBC radio which doesn't have any ads in the first place.
I am not surprised that a modern microwave oven in good condition (like the one in the photo) did not interfere with the LAN. However, an older oven (even a 300W one) with a faulty seal could easily radiate 100 times as much power and cause real problems.
Thought: If your microwave messes up your wireless LAN then get the oven professionally tested. An oven with a faulty seal can be dangerous.
You don't seriously think the ISP will ever recover that money, clause or no clause...
I have no idea. Like I said, IANAL. But, I simply don't like the idea of betting potentialy large sums of money on a company deciding not to enforce a contract clause. If ISPs and others with similar clauses (such as re-hosting companies) don't have any intention of using them, why put them in?
Once upon a time, I was a simple trusting soul who basically thought that if I dealt with large reputable firms all would be well. However, a few months of reading Slashdot (DeCSS, cue-cat etc) has lead me to the conclusion that large companies and corporations couldn't care less about screwing their customers over. My policy is now not to rely on trust.
Of course, if someone who is a UK lawyer were to demonstrate that I have nothing to worry about and that these clauses would not be enforceable then that would make my life significantly easier.
Just strike the offending clause out when you sign the agreement
Well, obviously, this often isn't physically possible because the agreement is an online contract-o-matic, (which I agree may not be legally binding). The solution wiith my current cable provider was to sign the paper agreement, which didn't mention indemnity and then click "I don't agree" at the contract-o-matic. This means that I don't get any email addresses or web space, but I can get those elsewhere and they haven't complained. As an additional protection, I pay by monthly cheque rather than direct debit. That way they need to take me to court to get money rather than just taking it and leaving me to fight to get it back again.
they wouldn't turn away good business.
Maybe not in the USA, but here in the UK following the Demon libel case ISPs are very nervous and will drop people's accounts at the first hint of trouble. If someone strike a clause then they are going to instantly suspect trouble!
The article points out on more than one occasion that ISPs will incure substantial costs investigation possible crimes on behalf of other nation's police forces.
However every ISP that I have ever dealt with has had an indemnity clause in their user agreement. Now, IANAL, but I get the impression that I have agreed that if my ISP spends money in staff and legal costs investigating a complaint about me from police in for example Riga or Washington then they can send me the bill and I will have to pay it.
Note: I am in the UK, but I assume that a similar system exists in other countries?
Now that the signal degradation is no longer being done, your commercial receiver is just as accurate as the military versions
Rubbish! Civilian receivers are much more accurate now that SA is switched off, but they are still not as good as military receivers (at least not without the use of differential GPS). Civilian receivers only receive the C/A code broadcast on the L1 frequency (1575 MHz). Military receivers also receive the P & Y codes broadcast on the L2 frequency (1228 MHz). The Y code is encrypted and yes, the codes are changed regularly.
There are several reasons why access to the L2 transmissions improved accuracy, but the most significant is probably ionopheric distortion. Essentialy, the signals from the satellited refract as they enter the atmosphere, thus they follow a path which is slightly longer than a straight line. The navigation codes attempt to allow for this, but the ionosphere is not static and civilian receivers only compensate for average conditions.
Now, you will remember from your physics classes that different wavelengths (or frequencies) refract by different amounts (thus a prism generates a spectrum). By measuring the difference in arrival time of the L1 and L2 channels from the same satellite one can determine more accurately the state of the ionosphere between the receiver and the satellite. By using this knowledge when deriving the nav solution the received can further increase its accuracy.
DERA (part of the UK MOD) have a large rail gun project. IIRC we have a 90mm calibre gun at a range in Scotland. The existance of the gun is not classified, but I haven't been able to find any URL's describing it.
As I recall (its not my department) the main benefit is maximum muzzle velocity. Apparently, normal powder guns run out of speed due to some physics associated with the speed of sound in the expanding gas. In tank guns muzzle velocity is the name of the game!
Ours works, but is far from being a deployable weapon. The current one uses a capacitor bank the size of a small house. Its obviously too big to go on a tank, but it was cheap and readily available. I understood that the Americans are working on some sort of wacky rotating machine called a "pulsed alternator", which would produce enough current and fit in a tank.
The other big advantage seems to be one of logistics. Rail guns run on diesel, powder guns run on high explosive. Which one would you rather have to lug around a battlefield?
There would be no such issue with GPL'ed programs written in Kylix. The only limitation is that the tool used to compile the program is not, in itself, GPLed. But it's a free download, so users would always have the right and the capability to modify the program they are using.
Only if they are using a platform supported by Borland. I can take any GPL'd program written with gcc and stand a good chance of making it work on my Alpha (or for that matter my ARM based RiscPC). Will that be the same for GPL'd code written with Kylix?
Do owners have good reasons to keep people out?
on
Infiltration
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· Score: 2
If I owned an old abondoned building I would try very hard to keep people out of it. Maybe I am paranoid, but I would be afraid of someone breaking in, injuring themselves and then sueing me for damages.
I seem to recall that here in the UK property owners are required by law to secure dangerous structures to prevent children from breaking in and injuring themselves.
Can you please start by providing an idiot's guide to how this CPRM thing is actually supposed to work.
I gain the impression that compliant (presumably closed source) software encrypts data as it flows on and off the drive using keys which are specific to each drive. So, if the file is moved to a different drive it won't decrypt any longer? Have I got the right idea? If so, its only applicable to those prepared to run closed source software, right?
I don't use my Linux machines to read "entertainment files" (MP3s, DVDs etc) or run any closed source software. I just read Slashdot, send email and hack code. Is there any reason why I wouldn't be able to continue doing this on one of these crippled drives?
If you watch TV or listen to the radio you are already dealing with ads. What makes the web different?
Ah, well here in the UK we have the BBC where there are no adverts:-). Yes, one has to buy a TV license, but that's only for TV. If, like me, one doesn't own a TV then one can listen to high quality advert free interlectual radio (I'm talking about Radio4 here) all day and its completely free.
Obviously, I do realise that eventually someone will either find some way of charging me or add adverts, but after about 20 years of free listening they haven't found a way yet:-).
Well, I read it and I remain unimpressed. It seems to consist mostly of asking game players about their perception of the effects of the games. Obviously, they aren't going to say "Well Guv, it makes me more aggressive and ruins my social life".
I'm sorry, but as a real (as opposed to social) scientist, I can't become excited by this sort of research. Folks claim that game playing improves reaction time, spacial awareness etc. This may well be true, but (a) we need to directly measure these factors and (b) consider whether they are useful for anything other than playing computer games better (not everyone can work as a fighter pilot). If they are only useful for playing games better, than that is not a problem, it just means that they can't be claimed as a net gain to society.
More importantly, are their any serious health effects? Again, something that can actualy be measured. Obviously, children are getting fatter, but that could just as easily be explained by television. But what about RSI? Where I work, huge effort is out into preventing diseases caused by excessive computer use. Might similar conditions effect excessive game players?
Have any of the statements in this article actually been verified by any sort of objective measurement at all?
Maybe they are very difficult to measure (how do you have a control group when practically all children play computer games), but has anyone actually tried?
I have seen gamers complain that there is no evidence that excessive game playing causes no harm. Well, maybe that is true, but one cannot then present unsubstantiated claims that it does any good.
I notice a trend these days to sell electronic products with transparent plastic cases (e.g. telephones). Does anyone make transparent keyboards? Such a thing would make it much harder to hide one of these sniffer gadgets and save me the trouble of taking my keyboard apart every week (as I intend to do from now on!).
Obviously I also need a transparent computer case and that could create EMC problems:-(.
Slashdot Mirror
The bottom line is that there is a fundamental limit to how much data can pass through a given amount of radio spectrum in a given period of time. Let's say you have 100 MHz of bandwidth available and 100 signal sources each generating enough data to fill 1 MHz of bandwidth. Now, we can divy up the spectrum in several different ways.
The obvious one is to place each source on a different frequency and since each one is 1 MHz wide we can just fit them all in. This is called frequency division multiplexing and its how FM radio works.
Next, we could get each signal to buffer 1 second of data and then transmit it at 100 times normal speed for 1/100th of a second. Increasing the data rate increases the bandwidth so each signal is now 100 MHz wide and uses the entire available spectrum, but if we get them to transmit one after the other we get 100 bursts each 1/100th second long and once again the channel is full. This is called time division multi access (TDMA) and it is how your GSM cellphone works.
Lastly, we can take each signal and mix it with a very high speed pseudo random data stream. The signal gets much wider, but the energy per unit bandwidth goes down. At the other end the received signal is mixed with the same random stream and the original signal re-appears. The maths is complex, but it turns out that if I spread each signal out to fill the 100 MHz then I can just about get them all in without them interfering with each other too much. This is called code division multiple access (CDMA) and is how GPS and 3rd generation cellphones work.
Now for the important bit. As you can see, we have 3 different ways to get 100 signals into out 100 MHz of bandwidth. We can choose any one of them, but we can't choose all three. If our 100MHz is already full of TDMA signals and we put 100 CDMA signals in the same spectrum then they will interfere.
Now, if I have a bandwidth which isn't being fully utilised (suppose for example I have only 10 frequency multilexed signals in my 100 MHz) then I can slip in a few CDMA signals and all will be well, but only a few. If I bung 50 in then the FM signals will start to suffer interference.
What Mr Fullerton has done is basically produced a modified version of CDMA which is spread over a very wide band. The radio spectrum is still not used very efficiently, so there is enough room over that huge bandwidth for quite a few of his transmitters to be fitted in. Provided that their average power is low and there not too close to your receiver. But you don't get something for nothing. He's not using new spectrum, just old spectrum in a different way. We could achieve exactly the same effect by taking conventional CDMA and just making the random bit stream much faster.
Finally, there are costs to his approach which is related to the huge bandwidth and that is making an effecient wideband antenna. As someone who designs antennas for a living I can tell you that making a wideband antenna which is efficient means sacrificing gain or size or both.
Linux advocate- Hello, I'm from RedHat Inc.
Law maker- Who?
Linux advocate- Hello, I'm from the Linux Industry Consortium. Our members include IBM, HP, Sun and RedHat.
Law maker- Hello. Pleased to meet you. Would you like a coffee?
Such a group would be able to excert pressure in other areas. For example, whilst Andre Hedrik's effort in the IDE standards committee are greatly appreciated, he has himself said that his influence is limited since he is just a lone consultant and can't officialy represent Linux.
I agree that creating such a body is going to produce numerous problems such as keeping it small enough to be responsive whilst not excluding people who feel they should be represented, and defining its role closely enough to prevent it from influencing things like kernel development. I also accept that we already have groups like FSF and Linux International, but if RedHat are having to go and lobby lawmakers then these groups clearly don't have the required clout. Obviously they could be members of the "Linux Industry Consortium" (I am sure we could find a better name).
How do we know that this hasn't happened already? Perhaps all US bases anonymizers have already been served with such orders (perhaps months ago). How would we know?
Are there any good anonymizers in other countries. I don't mind paying for one if it has a reasonable chance of being secure.
Thought: Would it be possible to construct some sort of mutual peer-to-peer anonymizer system. I'm thinking of something a little like FreeNet.
1) The MPAA isn't going after the users, its going after their ISP. A user who is falsely accused has an interest in defending the case, but their ISP doesn't and isn't likely to be interested in claims of innocence from their customer. After all, is that customer going to take their custom else where? How many people have a choice of broadband access providers?
2) It is my understanding (and I have read posts from those claiming to be lawyers which confirm this) that an innocent individual sued by someone like the MPAA has no choice but to comply, since they could never afford to defend the case.
Summary: I have no problem with copyright owners going after those who trade illegal copies provided that those who may be falsely accused have recourse to effective legal protection.
Do I understand that in this example Bob is a millionair Gnutella user? How else can he afford to defend a case against the MPAA to the point of being able to present expert witnesses?
Is this 2.4 GHz kit approved for aircraft use? If so then you have found a bargain. Does the $1200 include the cost of installing it? Where does the antenna go?
However, I have a horrible suspicion that you think that you can just take a commercial 2.4 GHz video transmitter and "put it on an aircraft". Have you any idea how much it would cost to get FAA approval for this (assuming they would allow it at all)? If we were talking a light aircraft with just you and your buddy on board then you might get away with it (or at least avoid a prison sentence if caught). But you are proposing to do it with fare paying passengers!!
Your biggest problem (well one of them) is going to be the antenna. Where are you going to put it, remembering that it needs to basically point down? If you fix it to the outside of the aircraft then that is an external modification which requires the approval of the design authority (usualy the plane's manufacturer). You need to prove to the FAA that it won't effect the aerodynamics. Obviously a small antenna won't but you need a official letter saying so and they cost a lots of money (thousands). You might be able to come up with some scheme involving a small patch which you can push out through the door (maybe!). If we weren't a government agency we could design such an installation for you. It wouldn't cost less than $4000. And as for the loony in another post who suggested fixing it on with sticky tape, well words fail me! What happens when it comes loose and the cable wraps itself round the tail? Well, at least some of those on board will have parachutes!!
Next, if the 2.4 GHz transmitter isn't type approved for flight use then you need it tested for EMC. Its not enough to say "nothing else on the aircraft uses 2.4 GHz". How do you KNOW that it doesn't produce some small spurious signals on a frequency which you do use? Again, this is going to cost thousands.
Remember, you can get away with quite a lot on small private aircraft and those with special experimental licenses (by which you can become your own design authority), but once you start carrying the paying public the rules get much tougher!!
Sheesh! The man didn't say there had been no totalitarian government. He said that we didn't have any experience of such government. How many people do you know who can remember back to 1290!!!!!!
What can we nerds do to reduce our exposure to this problem?
To take my own case:
So come one guys. Get a grip and address the real technical issues!
Oh, and regarding the USA and UK? All I can say is that if I could learn the language I'd move to Finland and go dogsledding every weekend :-)
What I (and many other idiots) need is a step by step idiot's guide to getting RPM signature verification working. Someone must have written such a thing, does anyone know where to find it? It won't allow me to achieve the supreme security level advocated by Mr Seifried, but I will be much better off than I am now.
As I understand it, the advertisers don't want their adds streamed since they will then have to pay more to the actors in the ads. So, the broadcasters are going to remove the problem ads from the online broadcasts. Therefore, those who listen online could end up with fewer ads :-)
Mind you, I'm in the UK and listen to BBC radio which doesn't have any ads in the first place.
Thought: If your microwave messes up your wireless LAN then get the oven professionally tested. An oven with a faulty seal can be dangerous.
I have no idea. Like I said, IANAL. But, I simply don't like the idea of betting potentialy large sums of money on a company deciding not to enforce a contract clause. If ISPs and others with similar clauses (such as re-hosting companies) don't have any intention of using them, why put them in?
Once upon a time, I was a simple trusting soul who basically thought that if I dealt with large reputable firms all would be well. However, a few months of reading Slashdot (DeCSS, cue-cat etc) has lead me to the conclusion that large companies and corporations couldn't care less about screwing their customers over. My policy is now not to rely on trust.
Of course, if someone who is a UK lawyer were to demonstrate that I have nothing to worry about and that these clauses would not be enforceable then that would make my life significantly easier.
Well, obviously, this often isn't physically possible because the agreement is an online contract-o-matic, (which I agree may not be legally binding). The solution wiith my current cable provider was to sign the paper agreement, which didn't mention indemnity and then click "I don't agree" at the contract-o-matic. This means that I don't get any email addresses or web space, but I can get those elsewhere and they haven't complained. As an additional protection, I pay by monthly cheque rather than direct debit. That way they need to take me to court to get money rather than just taking it and leaving me to fight to get it back again.
they wouldn't turn away good business.
Maybe not in the USA, but here in the UK following the Demon libel case ISPs are very nervous and will drop people's accounts at the first hint of trouble. If someone strike a clause then they are going to instantly suspect trouble!
However every ISP that I have ever dealt with has had an indemnity clause in their user agreement. Now, IANAL, but I get the impression that I have agreed that if my ISP spends money in staff and legal costs investigating a complaint about me from police in for example Riga or Washington then they can send me the bill and I will have to pay it.
Note: I am in the UK, but I assume that a similar system exists in other countries?
Rubbish! Civilian receivers are much more accurate now that SA is switched off, but they are still not as good as military receivers (at least not without the use of differential GPS). Civilian receivers only receive the C/A code broadcast on the L1 frequency (1575 MHz). Military receivers also receive the P & Y codes broadcast on the L2 frequency (1228 MHz). The Y code is encrypted and yes, the codes are changed regularly.
There are several reasons why access to the L2 transmissions improved accuracy, but the most significant is probably ionopheric distortion. Essentialy, the signals from the satellited refract as they enter the atmosphere, thus they follow a path which is slightly longer than a straight line. The navigation codes attempt to allow for this, but the ionosphere is not static and civilian receivers only compensate for average conditions.
Now, you will remember from your physics classes that different wavelengths (or frequencies) refract by different amounts (thus a prism generates a spectrum). By measuring the difference in arrival time of the L1 and L2 channels from the same satellite one can determine more accurately the state of the ionosphere between the receiver and the satellite. By using this knowledge when deriving the nav solution the received can further increase its accuracy.
As I recall (its not my department) the main benefit is maximum muzzle velocity. Apparently, normal powder guns run out of speed due to some physics associated with the speed of sound in the expanding gas. In tank guns muzzle velocity is the name of the game!
Ours works, but is far from being a deployable weapon. The current one uses a capacitor bank the size of a small house. Its obviously too big to go on a tank, but it was cheap and readily available. I understood that the Americans are working on some sort of wacky rotating machine called a "pulsed alternator", which would produce enough current and fit in a tank.
The other big advantage seems to be one of logistics. Rail guns run on diesel, powder guns run on high explosive. Which one would you rather have to lug around a battlefield?
Only if they are using a platform supported by Borland. I can take any GPL'd program written with gcc and stand a good chance of making it work on my Alpha (or for that matter my ARM based RiscPC). Will that be the same for GPL'd code written with Kylix?
I seem to recall that here in the UK property owners are required by law to secure dangerous structures to prevent children from breaking in and injuring themselves.
I gain the impression that compliant (presumably closed source) software encrypts data as it flows on and off the drive using keys which are specific to each drive. So, if the file is moved to a different drive it won't decrypt any longer? Have I got the right idea? If so, its only applicable to those prepared to run closed source software, right?
I don't use my Linux machines to read "entertainment files" (MP3s, DVDs etc) or run any closed source software. I just read Slashdot, send email and hack code. Is there any reason why I wouldn't be able to continue doing this on one of these crippled drives?
Anyone want to produce a suitable map file?
Ah, well here in the UK we have the BBC where there are no adverts :-). Yes, one has to buy a TV license, but that's only for TV. If, like me, one doesn't own a TV then one can listen to high quality advert free interlectual radio (I'm talking about Radio4 here) all day and its completely free.
Obviously, I do realise that eventually someone will either find some way of charging me or add adverts, but after about 20 years of free listening they haven't found a way yet :-).
BTW, most, if not all, of Radio4 is now streamed.
I'm sorry, but as a real (as opposed to social) scientist, I can't become excited by this sort of research. Folks claim that game playing improves reaction time, spacial awareness etc. This may well be true, but (a) we need to directly measure these factors and (b) consider whether they are useful for anything other than playing computer games better (not everyone can work as a fighter pilot). If they are only useful for playing games better, than that is not a problem, it just means that they can't be claimed as a net gain to society.
More importantly, are their any serious health effects? Again, something that can actualy be measured. Obviously, children are getting fatter, but that could just as easily be explained by television. But what about RSI? Where I work, huge effort is out into preventing diseases caused by excessive computer use. Might similar conditions effect excessive game players?
Maybe they are very difficult to measure (how do you have a control group when practically all children play computer games), but has anyone actually tried?
I have seen gamers complain that there is no evidence that excessive game playing causes no harm. Well, maybe that is true, but one cannot then present unsubstantiated claims that it does any good.
Obviously I also need a transparent computer case and that could create EMC problems :-(.