Think GPS is cool? IPS will blow your mind

GPS is complex and I may be wrong. But for rebroadcast to work the transceiver would need to be placed exactly between the user and the satellite in space; meaning a different location every time the user moves. If not perfectly placed; the radio signal will have travelled further than expected and give the wrong position. I suppose you could attempt to locally recreate GPS signals with multiple transmitters; but this would play havoc with GPS reception outside the building. Why not just use WIFI?

Differential GPS is not about rebroadcasting the actual GPS position, but the error from a known position. This allows the device to enumerate the error caused by atmospheric effects.

The location of each GPS transmitter must be known exactly for the triangulation to work, and existing GPS receivers know nothing about the location of shopping-mall transmitters. They only know about satellites.

So that's why you couldn't do this with existing receivers, but I don't know of any reason why you couldn't make new receivers that cooperate with a new type of ground-based transmitter built into cell towers or similar. Multipath might be a problem but it seems surmountable. Do any radio experts here know why nobody has done anything like this for cell phones? (The Wi-Fi/Bluetooth positioning talked about in the article is based solely on signal strength which is far inferior to the GPS method).

Differential GPS doesn't work indoors, I thought?

The main problem is that wireless signals simply aren't reliable. You could "boost" GPS indoors, but that doesn't get around the fact that there are corners, concrete walls, mirrors, humans, and so on.

Anyway, we're splitting hairs. The point is that we don't currently have an IPS. It doesn't matter if we extend GPS to work indoors or use other signals to create an IPS -- the point is, we need to create an IPS :)

iirc there are several short-range positioning signals (various flavors of differential GPS, i guess)

> I was in a Target yesterday (where I almost never go) and started getting really irritated by the fact that kitchen utensils etc., were segregated by brand instead of by function.

In some cases, that might be because of shipping and (re)stocking logistics. I would guess that OXO products come to the retailer in one shipment, Le Creuset products in another shipment, etc. Especially when profit margins are thin, the retailer might not be interested in paying employees to re-sort products of different brands into functional groups. That'd be even more true if stocking were done by representatives of the different manufacturers or their distributors.

It ought to be good enough for absolute position. The general arrangement of lights, air vent, smoke alarm, sprinkler, motion detector, and wall proximity are more than likely unique.

If you check out SLAM positioning, you can do some really amazing stuff even if all you know is how far away from the wall you are. Given a decent floor plan, you simply take frequent distance measurements as you wander around, using dead reckoning (the accelerometer will help) to keep track of your relative positions. You rapidly build up a local map of the walls near you, which eventually will map uniquely to one location on the floor plan. Our robot only had to wander for a few seconds to figure out where it was, and that was just using a few ultrasonic rangefinders.

I haven't heard of such a thing, but I imagine you could do something similarly cool with the camera of your phone. Or, even the accelerometer and compass, combined with a knowledge of the locations of doors and the available walking paths, may be able to give a reasonably good approximation of your current location--if you walked north for 30 meters, then turned left and walked another 20 meters, then north for an additional 5, in a typical mall that's going to limit the number of points you could be occupying.

Why not? I guess the features would have to be large/visible enough to be picked up by the camera. For initialization some kind of qr-codes could be placed wihtin the relative positioning patterns...

I use GPS to fly UAVs and I've seen errors in GPS altitude up to 50ft compared to barometric altitude. Generally it's better than that, though. It's accurate enough for us to fly autonomous helicopters with the barometric sensor disabled. I'd say that disproves the inaccurate and low-resolution claims ;-)

No, it's true. The possible geometry of visible GPS satellites at any given moment (namely that they're all above you and none are below) means that the vertical error is pretty bad in comparison to the horizontal error.

I'm sure most of the responses to your comment have technical reasons for their disagreement, but I agree with you for anecdotal reasons.

I have a Garmin GPS I wear when I run, it connects to 3 (at least?) satellites and I've never seen it be off by more than a few feet in altitude. I'm sure there are some random points in the graph with anomalous readings but the overall "smoothed" graph seems very accurate.

Granted, there are times it loses its signal altogether, but that is not a resolution issue.

I got a certificate in GIS back in 2002. Dusting off my brain: All GPS readings are only accurate to within about 10 meters if they are quick and dirty. To get accurate readings, you need multiple satellites in view for up to several hours.

I am assuming that has not really changed. Anyone with brand spanking new credentials or more current industry experience feel free to correct/update. Thanks.

Commerce isn't a bad thing, but exciting new technology to try to separate me from my money faster may be a cool thing for Google, but not for me--the consumer. Maybe I'm weird, but I already know what I want to buy, I don't need technology to try (and usually fail) to generate some new consumption desire.

You're right... it could also be used to oppress people.