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Assisted GPS (aGPS) 
For a while now, a rumor has been going through the Internet about aGPS or Asissted GPS or in full Asissted Global Positioning System.
The rumor is that aGPS is worse then GPS, or even, is no GPS at all.
So when a spec sheet of a new device comes along and it lists aGPS, people freak and curse that it won't have GPS and that they wish it had and might buy a bluetooth GPS to go with it, etc.
Ok, let's try and set the record straight.
aGPS is always full GPS
aGPS is better then GPS
aGPS is a hardware GPS chip combined with "intelligent" software
aGPS does not require 3G, but is helped by it
There you go!
Some explanation. GPS uses satellites to triangulate it's position. To do this it needs to "see" (direct line of sight is not required) multiple satellites to get a fix. The more satellites it can see, the better. I believe that most GPS chips can see a maximum of 12 to 13 satellites at the same time. Depending on where you are on earth, the maximum satellites you can see ranges from 9 to 15. It is influenced by the curvature of the earth. About 3 or 4 are required to get accurate data. More satellites means better accuracy.
The problem with this system is that the initial fix can take 2 minutes or more. This is because the GPS has no idea where in the world it is, so it needs time to figure this out.
THAT is why aGPS was invented. The "a" in aGPS is software in your device which tries to figure out where you are in the world, quicker then your GPS hardware chip can.
In general it uses 2 methods to do this:
1. It will try to do this using your external internet IP (very rough, but it can pick your country quite easily because of your IP subnet or provider or DNS suffix).
2. It can also leverage your 3G connection to ask the tower it's connected to it's cell tower identification number. Using a database of these towers it will look up the coordinates of that tower and it instantly knows where you approximately are.
It then relays this to your hardware GPS chip so that it can narrow it's search region considerably and give you a quicker fix. Often within 10 to 20 seconds.
That is all it does, and ever will do. Spread the word!
The rumor is that aGPS is worse then GPS, or even, is no GPS at all.
So when a spec sheet of a new device comes along and it lists aGPS, people freak and curse that it won't have GPS and that they wish it had and might buy a bluetooth GPS to go with it, etc.
Ok, let's try and set the record straight.
aGPS is always full GPS
aGPS is better then GPS
aGPS is a hardware GPS chip combined with "intelligent" software
aGPS does not require 3G, but is helped by it
There you go!
Some explanation. GPS uses satellites to triangulate it's position. To do this it needs to "see" (direct line of sight is not required) multiple satellites to get a fix. The more satellites it can see, the better. I believe that most GPS chips can see a maximum of 12 to 13 satellites at the same time. Depending on where you are on earth, the maximum satellites you can see ranges from 9 to 15. It is influenced by the curvature of the earth. About 3 or 4 are required to get accurate data. More satellites means better accuracy.
The problem with this system is that the initial fix can take 2 minutes or more. This is because the GPS has no idea where in the world it is, so it needs time to figure this out.
THAT is why aGPS was invented. The "a" in aGPS is software in your device which tries to figure out where you are in the world, quicker then your GPS hardware chip can.
In general it uses 2 methods to do this:
1. It will try to do this using your external internet IP (very rough, but it can pick your country quite easily because of your IP subnet or provider or DNS suffix).
2. It can also leverage your 3G connection to ask the tower it's connected to it's cell tower identification number. Using a database of these towers it will look up the coordinates of that tower and it instantly knows where you approximately are.
It then relays this to your hardware GPS chip so that it can narrow it's search region considerably and give you a quicker fix. Often within 10 to 20 seconds.
That is all it does, and ever will do. Spread the word!
Logitech keyboard warning
While I hate to rant about logitech, I really feel I have to right now.
This is a bad and good story. The good I can be quite quick about. I have a Logitech illuminated keyboard of which a key broke off. I emailed Logitech asking them if I could receive a spare key and they sent me a whole new keyboard free of charge! Excellent excellent service!
But while I was 'without' a good keyboard I decided to invest in a nice small Logitech K340 keyboard. As I am situated in my living room, space is of an issue. I use a laptop table for my keyboard and mouse. So I bought the smaller K340 wireless keyboard and M510 wireless mouse would make a good combo. These together would give me more space on the little table. Also, I haven’t tried wireless tech for a few years because in the past it has always left me disappointed,
Well, the wireless tech does not disappoint. When the receiver is close enough (within a meter or so) it is really good and I’m hard pressed to tell the difference with a wired keyboard and mouse. Very very happy with it. The keyboard types great, it’s nice and compact. The software is finally good, very Spartan, doesn’t act weird or change things you don’t want. Great…
But then I started realizing something weird. While playing some games, I noticed that certain key combinations where not possible! Causing some weird reactions you would not expect.
After some testing, it turns out that the keyboard has some weird limitations you would not expect of such a product. Often used gaming keys include a quadrant called WASD. These keys are often used for movement and are also often combined with either the shift key or the spacebar.
As it turns out, this keyboards design prohibits you from doing this. W+D+Space does not respond at all. Checking this with a keyboard checking tool called “keyscan 0.9” it turns out that this indeed is not working. Even more strange is to find out that W+A+Space does work! Moving your hands one key to the right going to a quadrant of ESDF, it turns out all the combinations are working just fine. You can even hit 7 keys at the same time, and they all register just fine. So, Shift+E+S+D+F+Space works, but W+D+Space does not. Even S+D+Space works.
It turns out that there have been a few topics about this already and that it’s a hardware limitation that Logitech has put in their products. They say unintentionally, but I can’t really believe that. You would have to have the most incompetent keyboard matrix designer in the whole world to make this mistake in a keyboard. Even a budget keyboard of 8$ dollar does this just fine and then this keyboard of 60$ does not? There is just no forgiving this.
And I am really bothered by it, because on every other front this keyboard is a big win…. I mean 3 years battery life on a pair of AA batteries! Just that little ‘mistake’ makes it completely unusable for me.
Why they would choose to ruin such a great product with such a limitation is completely beyond me. I was not warned before buying it, so I’m stuck with it. I’ll use it as a server keyboard or something, because beyond that, it just won’t do. Even playing simplistic flash games now and then, it might block.
So everyone, a fair warning: When buying Logitech products, don’t assume you’re buying something well thought out anymore. Check the internet and the forums to see if they made some horrible design mistakes with it, and look further.
And Logitech. If your reading this, please fix your broken hardware and contact me for a replacement model. When you do so, I will edit this post to reflect just that.
My experience with your support and warranty has been superb up till now, so please, surprise me again with great service and offer this to everyone whom bought your broken product. If you can’t fix it that way. Please, put up a warning which keyboard will and will not function correctly, and don’t respond with that this isn’t a “gamers line” keyboard.
This is a bad and good story. The good I can be quite quick about. I have a Logitech illuminated keyboard of which a key broke off. I emailed Logitech asking them if I could receive a spare key and they sent me a whole new keyboard free of charge! Excellent excellent service!
But while I was 'without' a good keyboard I decided to invest in a nice small Logitech K340 keyboard. As I am situated in my living room, space is of an issue. I use a laptop table for my keyboard and mouse. So I bought the smaller K340 wireless keyboard and M510 wireless mouse would make a good combo. These together would give me more space on the little table. Also, I haven’t tried wireless tech for a few years because in the past it has always left me disappointed,
Well, the wireless tech does not disappoint. When the receiver is close enough (within a meter or so) it is really good and I’m hard pressed to tell the difference with a wired keyboard and mouse. Very very happy with it. The keyboard types great, it’s nice and compact. The software is finally good, very Spartan, doesn’t act weird or change things you don’t want. Great…
But then I started realizing something weird. While playing some games, I noticed that certain key combinations where not possible! Causing some weird reactions you would not expect.
After some testing, it turns out that the keyboard has some weird limitations you would not expect of such a product. Often used gaming keys include a quadrant called WASD. These keys are often used for movement and are also often combined with either the shift key or the spacebar.
As it turns out, this keyboards design prohibits you from doing this. W+D+Space does not respond at all. Checking this with a keyboard checking tool called “keyscan 0.9” it turns out that this indeed is not working. Even more strange is to find out that W+A+Space does work! Moving your hands one key to the right going to a quadrant of ESDF, it turns out all the combinations are working just fine. You can even hit 7 keys at the same time, and they all register just fine. So, Shift+E+S+D+F+Space works, but W+D+Space does not. Even S+D+Space works.
It turns out that there have been a few topics about this already and that it’s a hardware limitation that Logitech has put in their products. They say unintentionally, but I can’t really believe that. You would have to have the most incompetent keyboard matrix designer in the whole world to make this mistake in a keyboard. Even a budget keyboard of 8$ dollar does this just fine and then this keyboard of 60$ does not? There is just no forgiving this.
And I am really bothered by it, because on every other front this keyboard is a big win…. I mean 3 years battery life on a pair of AA batteries! Just that little ‘mistake’ makes it completely unusable for me.
Why they would choose to ruin such a great product with such a limitation is completely beyond me. I was not warned before buying it, so I’m stuck with it. I’ll use it as a server keyboard or something, because beyond that, it just won’t do. Even playing simplistic flash games now and then, it might block.
So everyone, a fair warning: When buying Logitech products, don’t assume you’re buying something well thought out anymore. Check the internet and the forums to see if they made some horrible design mistakes with it, and look further.
And Logitech. If your reading this, please fix your broken hardware and contact me for a replacement model. When you do so, I will edit this post to reflect just that.
My experience with your support and warranty has been superb up till now, so please, surprise me again with great service and offer this to everyone whom bought your broken product. If you can’t fix it that way. Please, put up a warning which keyboard will and will not function correctly, and don’t respond with that this isn’t a “gamers line” keyboard.