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NP Monday September 26, 2016

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45 minutes ago, CritterKeeper said:
3 hours ago, mlooney said:

Sounds more like an "in head display"

Maybe, but Elliot is seeing the map, not just sensing the GPS info.

1) He still DOES sense the coordinates. He said he know our exact GPS coordinates not that he see them written somewhere.

2) Seeing the MAP. Not map with the buttons and other control elements map applications generally have. He knows where are nearby restaurants, he don't see the icons on the map.

3) How you think sensing GPS info works? Brain have limited options how to make sense of sensory input. People can taste words, seeing sounds and hear colors, of course if you have some new sense it would seems to you as similar to what you had before.

He doesn't interact with the phone as separate unit, just virtual one instead of physical. He really gains some abilities based on what the phone can do. Of course, we were given just a very limited example ; it would be very interesting to see what abilities he get based on other applications, especially games - can he now cheat in games? (Hmmm ... is he too honest to even try?)

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3 hours ago, CritterKeeper said:

Maybe, but Elliot is seeing the map, not just sensing the GPS info.

True, but he also got the latitude and longitude, which may or may not have been visual information.

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IMHO we have insufficient information on this question. Also there isn't necessarily just one answer.

Apparently he does have to at least think about his phone to activate its functions. (Or have something external happen that would activate it and draw it to his attention, such as someone calling him.)

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1 hour ago, Don Edwards said:

IMHO we have insufficient information on this question. Also there isn't necessarily just one answer.

We do have little information, as usually. But I think it is sufficient for disproving him using phone as single separate unit.

1 hour ago, Don Edwards said:

Apparently he does have to at least think about his phone to activate its functions.

It actually seems he need to think about the FUNCTION, not about the phone.

Also ... activate ... I know how long it takes to get position after activating GPS. Given how quickly he got answer, the GPS WAS active, he just wasn't aware of it. He needed to activate the map, yes.

(And BTW, knowing position from GPS ... I don't think Grace would be able to compute the necessary calculations so quickly.)

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3 hours ago, hkmaly said:

1) He still DOES sense the coordinates. He said he know our exact GPS coordinates not that he see them written somewhere.

2) Seeing the MAP. Not map with the buttons and other control elements map applications generally have. He knows where are nearby restaurants, he don't see the icons on the map.

3) How you think sensing GPS info works? Brain have limited options how to make sense of sensory input. People can taste words, seeing sounds and hear colors, of course if you have some new sense it would seems to you as similar to what you had before.

He doesn't interact with the phone as separate unit, just virtual one instead of physical. He really gains some abilities based on what the phone can do. Of course, we were given just a very limited example ; it would be very interesting to see what abilities he get based on other applications, especially games - can he now cheat in games? (Hmmm ... is he too honest to even try?)

You are vastly expanding the scope of the discussion.  Someone said he didn't have a heads-up display, and I pointed out a quote that showed he did.  I didn't say there weren't other aspects to the spell.  In fact, I specifically referred to him sensing the GPS info.  Please take another look at what I actually said, and stop implying I said all that other stuff.

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19 hours ago, CritterKeeper said:

You are vastly expanding the scope of the discussion.  Someone said he didn't have a heads-up display, and I pointed out a quote that showed he did.  I didn't say there weren't other aspects to the spell.  In fact, I specifically referred to him sensing the GPS info.  Please take another look at what I actually said, and stop implying I said all that other stuff.

I wasn't aware expanding the scope of the discussion was something negative :)

Yes, it was Chridd who started the "thread" with the assumption Elliot has to go through the phone. I replied that he didn't mentioned any HUD. I've got the impression you want to back him up with your reply. If that impression was incorrect, sorry, seems I've got carried away.

The issue actually wasn't if he has heads-up display, but if he has heads-up display containing the controls and status of the phone.

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My point was that he (probably) doesn't have direct access to all the signals that his phone can see, but rather that his abilities are more similar to what he could do if he were just using the phone normally (seeing the screen being one possible way that could work, but it could be some subspell that does the same sorts of things).  That is, he can talk on the phone, he can see a map and determine GPS coordinates (since there are apps/features that show GPS coordinates) and get driving direction, and he could probably send text messages and browse the internet and take pictures, but probably can't see where exactly the GPS satellites are or the specific bytes his phone is receiving from the cell carrier.

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10 minutes ago, chridd said:

My point was that he (probably) doesn't have direct access to all the signals that his phone can see, but rather that his abilities are more similar to what he could do if he were just using the phone normally (seeing the screen being one possible way that could work, but it could be some subspell that does the same sorts of things).  That is, he can talk on the phone, he can see a map and determine GPS coordinates (since there are apps/features that show GPS coordinates) and get driving direction, and he could probably send text messages and browse the internet and take pictures, but probably can't see where exactly the GPS satellites are or the specific bytes his phone is receiving from the cell carrier.

Oh. That's different to how I understood it.

He definitely can't see where the GPS satellites are as the phone itself have no idea. The calculations are based on HOW FAR they are, not angle. But yes, I agree he can't sense that either. He can likely sense when he lose GPS signal, though.

And, yes ... we would know more if he tried to play some game :), but when I was talking about sensing WiFi, I meant something like "there is WiFi with SSID thwiggle on seventh channel", not the bytes received. You can get SSID directly from OS and I have app showing the channel for example.

It would be roughly what he can do with the phone, but it won't work exactly same way as with the phone. It would be more like multiple separate abilities than one thing with menu/list of apps.

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40 minutes ago, hkmaly said:

He can likely sense when he lose GPS signal, though.

That depends on if the signal isn't changed in some way, outgoing signals are likely boosted by magic and could bypass conventional jamming techniques, incoming signals on the other hand might not be received as easily unless the Cheerleadra form generates some sort of field that acts as a large antenna. One way to find out would be to have Elliot go into a parking garage or something with a lot of concrete and metal and no wi-fi nodes inside.

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3 minutes ago, Scotty said:
53 minutes ago, hkmaly said:

He can likely sense when he lose GPS signal, though.

That depends on if the signal isn't changed in some way, outgoing signals are likely boosted by magic and could bypass conventional jamming techniques, incoming signals on the other hand might not be received as easily unless the Cheerleadra form generates some sort of field that acts as a large antenna. One way to find out would be to have Elliot go into a parking garage or something with a lot of concrete and metal and no wi-fi nodes inside.

Well, there are no outgoing signals in case of GPS. Even just the ability to use whole body as antenna (as opposed to the little antenna in phone) would be some boost, but I don't think it would be enough to get signal inside parking garage with at least one floor full of metal cars above you.

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On 2016-09-30 at 2:51 AM, hkmaly said:

He definitely can't see where the GPS satellites are as the phone itself have no idea. The calculations are based on HOW FAR they are, not angle. But yes, I agree he can't sense that either. He can likely sense when he lose GPS signal, though.

Actually, part of GPS is calculating the exact positions of all the satellites. It wouldn't work otherwise.

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2 hours ago, lonjil said:

Actually, part of GPS is calculating the exact positions of all the satellites. It wouldn't work otherwise.

But isn't that the satellites' job?

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55 minutes ago, Don Edwards said:

But isn't that the satellites' job?

No, the GPS Satellites send out regular signals and GPS receiver units calculate their current position by triangulating the signals from four or more satellites.  Each satellite only needs to know its own position and the exact time.

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The key is that the satellite transmits its own coordinates instead of the receiver having to assume that its lookup tables are correct. This allows the receiver to extrapolate its own location using the time-of-transit of the radio signals.

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7 hours ago, lonjil said:
On 09/30/2016 at 2:51 AM, hkmaly said:

He definitely can't see where the GPS satellites are as the phone itself have no idea. The calculations are based on HOW FAR they are, not angle. But yes, I agree he can't sense that either. He can likely sense when he lose GPS signal, though.

Actually, part of GPS is calculating the exact positions of all the satellites. It wouldn't work otherwise.

3 hours ago, ijuin said:

The key is that the satellite transmits its own coordinates instead of the receiver having to assume that its lookup tables are correct. This allows the receiver to extrapolate its own location using the time-of-transit of the radio signals.

... right. The GPS satellite sends exact time and it's position. The phone detects when the signal arrived, then computes the time-of-transit from the time of arrival and time in signal and then uses the position the satellites told him they're on and compute it's own position from that.

(In fact, phone usually assumes it's own time is incorrect and uses modified algorithm with more satellites instead.)

I don't think it ever computes the angle to satellites. Technically it could do that AFTER it determines it's position, but it would be additional step useless for determining position. Unless it's used in some optimization for continued operation ...

I see there is at least one app showing position of satellites, so I guess Elliot can see that at least if he had that app installed.

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Angle doesn't really matter anyway, since there is exactly one point in Euclidean 3D space that is exactly the specified distances from four other points (assuming that the four points do not share a single 2D plane). It may however be worthwhile to listen to a second quartet of satellites in order to get a second opinion (and thus greater precision, especially if there is signal distortion or interference).

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The accuracy possible increases with the number of satellites used. When the GPS system was new the high accuracy was considered a problem as it could be used by a foreign military. To prevent this a pseudo random time modifier was used by the satellites. This degraded signal was believed to allow for an accuracy of about 100 yards which was thought to be good enough for civilian uses. The US military GPS receivers were able to use the same pseudo random algorithm to calculate the original time and thus were able to achieve the full accuracy that the system is capable of.

While an accuracy of 100 meters might have been fine for some civilian use it wouldn't be good enough for something like a GPS navigator for a car. But through some software trickery GPS manufacturers were able to increase the accuracy to about 25 yards. This was much better but not enough for really demanding applications, and that's when someone dreamed up Differential GPS. By having a stationary GPS receiver transmit the satellite data to a computer they could calculate how large the time error was. That data was then sent as a radio signal that DGPS capable receivers would use to correct their received satellite signals. In favorable situations it was possible to get an accuracy of about 4 inches this way.

Around 2000 it was determined that as DGPS had made it possible to achieve greater accuracy than what the military grade GPS receivers was capable of there was no reason to keep degrading the service for civilian use and the feature was turned off. Even so DGPS is still used for demanding applications today as it can correct some errors introduced by the atmosphere.

Modern GPS receivers can track a large number of satellites simultaneously. While in theory it should be possible to triangulate your position using 3 satellites 4 is actually considered the minimum that's usable and 6 is adequate for most purposes. But modern GPS receivers can track many more than that. Tests show that there are significant improvements even going from 13 to 15 tracked satellites, it can improve the accuracy from about 2 yards to about one.

 

Note that you may get excellent accuracy with only four satellites if the reception is good, but using more satellites improves the reliability.

And why on earth did I feel compelled to write this? I really don't remember, but perhaps it was to remind people just how amazingly complex the GPS system is, and yet we take it for granted today as almost all new mobiles and pads has GPS capability.
 

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2 hours ago, Cpt. Obvious said:

And why on earth did I feel compelled to write this? I really don't remember, but perhaps it was to remind people just how amazingly complex the GPS system is, and yet we take it for granted today as almost all new mobiles and pads has GPS capability.

Nonetheless I thank you for it. It was interesting, I hardly knew half of all that :)

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3 hours ago, Cpt. Obvious said:

Modern GPS receivers can track a large number of satellites simultaneously. While in theory it should be possible to triangulate your position using 3 satellites 4 is actually considered the minimum that's usable and 6 is adequate for most purposes. But modern GPS receivers can track many more than that. Tests show that there are significant improvements even going from 13 to 15 tracked satellites, it can improve the accuracy from about 2 yards to about one.

You can only triangulate with 3 satellites if your own clock is synced. THAT's why 4 is minimum. And note that inside or between buildings, GPS receiver is lucky to get 4 satellites. I also suspect, based on what GPS of my phone does when I'm home, that GPS signal can reflect from buildings.

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4 hours ago, Cpt. Obvious said:

Around 2000 it was determined that as DGPS had made it possible to achieve greater accuracy than what the military grade GPS receivers was capable of there was no reason to keep degrading the service for civilian use and the feature was turned off. 

And within hours someone online said, "I'll bet I could hide a treasure chest off in the woods, and post the GPS coordinates, and you guys could find it just based on those coordinates!"  And he did, and they did, and thus was born the hobby of Geocaching!

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10 minutes ago, CritterKeeper said:
4 hours ago, Cpt. Obvious said:

Around 2000 it was determined that as DGPS had made it possible to achieve greater accuracy than what the military grade GPS receivers was capable of there was no reason to keep degrading the service for civilian use and the feature was turned off. 

And within hours someone online said, "I'll bet I could hide a treasure chest off in the woods, and post the GPS coordinates, and you guys could find it just based on those coordinates!"  And he did, and they did, and thus was born the hobby of Geocaching!

... you mean geocaching didn't started with DGPS already?

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15 hours ago, hkmaly said:

... you mean geocaching didn't started with DGPS already?

I don't think there were many DGPS capable receivers back then that were portable. I think it was back in 98 that the US army was able to replace their old 35 pound GPS receivers with a new portable one weighing in at about 4 pounds. This was the result of a huge investment in research into developing a miniaturized receiver. And I'm pretty sure these didn't have DGPS capability, and they probably were very expensive.

Having said that I can't help wondering about the history of geocaching.
 

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Geocahing wouldn't be nearly as much fun if you knew where the cache was to within four inches!  The GPSr gets you to the right general area, but the cache is also camoflaged to prevent accidental discovery by Muggles.  Figuring out how it's hidden is a big part of the challenge!

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