More specifically, does CL require the user to have a data connection? Or is it possible to just use the phones service connection?
Thanks!
It actually uses several mechanisms.
GPS
Cell Tower Triangulation
Wifi Hotspot cataloging
Randomly assuming you are in Cupertino
There are tradeoffs based on speed, precision, and available hardware. A first Gen iPad will only have the 3 option available while the iPhone simulator makes use of the last mechanism.
You can observe the difference in these systems in the map application where it initially guesses based on the cell tower, then refines the guess via GPS.
Only options #3 requires a data connection.
And for the humor impaired including #4 was not totally serious although it is functionally correct. (I think they simulate the GPS reporting that location rather than just hard coding it, but I haven't checked.)
You can set the phone into airplane mode and still get a location :)
It will be forced to use GPS to get it so it might take longer to get though.
Related
I'm developing navigation system for my university as some kind of research activity. I'm using SVGKit to display floor plans. And now I need to provide user locationing service for navigation and tracking. So here's my questions:
1) Do I need some special hardware installed in university (Cisco MSE for example, or some cheaper analogues), or I can apply some software/technologies to our current hardware for server-side user location determining? If I do, what equipment do I need for it? I mean, it would be one unit for the whole university, or one per each floor, or what?
2)
Q: Why doesn't the Redpin iPhone client conform to the iPhone SDK
Agreement? A: Apple does not provide a public API to retrieve WiFi
data. In order to get the iPhone client working we had to use a
private API, which is disallowed by the iPhone SDK Agreement.
(c) http://redpin.org/faq.html Does it mean that RedPin is unacceptable in AppStore, so I can't use it?
3)Does Navizon I.T.S. requires some specific hardware equipment except standart routers?
Thank you all, maybe you can offer me better solutions, I hope. Thanks in advance.
Indoor positioning is a very vast field and many different solutions are available which all use a different combination of hardware/software. Some need no specific hardware to work, others need a very expensive infrastructure to be put in place. In the end, it all depends on the accuracy you are trying to achieve. Here are the most common solutions used, I ordered them by the type of technology used:
Wifi: two main techniques are used here, trilateration and fingerprinting. Both do not require specific hardware if your uni already has deployed access points (APs). Trilateration converts signal strength to distance and then intersect circles (almost exactly like GPS). In general this has poorish accuracy and you need to know the exact position of APs for it to work. Fingerprinting is a pattern matching technique where you first build a wireless map of the environment and then match the measurement against this map.
Bluetooth: same techniques as above can be used with Bluetooth nodes. Of course, there's less Bluetooth nodes than Wifi so you might need to deploy some extra nodes for it to be accurate enough. Same accuracy as Wifi (roughly 5 meters)
Dead reckoning: uses an accelerometer, gyroscope and compass to calculate the speed of heading of the user. Needs to be initialized and calibrated regularly by another absolute positioning technique. Subject to drift so accuracy degrades quickly over time. Upside is its very cheap, no extra hardware or initial survey phase are needed.
UWB: very accurate techniques based on time of flight measurements. Requires expensive hardware for both transmitter and receiver. You can achieve cm accuracy with this but it's probably not what you're after
This is still an field of research so it's not that easy to find something that just works. I suggest contacting the IT department of your university, if they run a Cisco system, I know some of them provide some sort of positioning capabilities but I don't have much details.
As for your iPhone question, any app that accesses the private API to access Wifi measurements will be rejected by the App store, so you won't be able to publish anything that relies on Wifi. You can still use it for research purpose though, you'll just have to figure out the code yourself as there's no official documentation (some unofficial doc is out there though)
Good luck!
Im working on a application for which I need to decide in which country the user is. Which is the most accurate way to do this?
Should I use GPS or IP-adress?
What would be the pros/cons with each method?
I would use Apple's location services, which use several technologies (cell towers, WiFi hotspots, GPS, etc.) to determine their location. You can then find the country quite easily with a lookup of the GPS coordinates. I think this would be more accurate than by-IP lookups.
Its probably easier if you go via ip address and use a geo ip lookup service.
For GPS the GPS unit needs to be turned on. I guess lots of people disable it for energy saving. If you just turn on GPS for your check the user needs to get a gps fix first which can be time consuming as well.
I would like to locate the iPhone in a building to build an application with similar features as the iPhone app of the American Museum of Natural History. There is no good GPS reception as there are also rooms in the cellar I would like to cover.
What can save me is that there is good wifi coverage in the whole area, so my idea was to triangulate the position based on the wifi base stations in range, whose positions are known. However I found no public API to find out which base stations are in range.
Questions
Do you have an idea how the app mentioned above manages to get the correct location indoors?
Could one add the wifi base stations manually to Apple's database and use the usual CoreLocation?
Do you have other ideas how to implement it?
Any help is very much appreciated!
Boundary conditions
The indoor navigation is only used during an event to guide guests new to the building, so no complex infrastructure should be installed.
There are approximately 14-18 rooms to be covered. They are in different parts of the building, so wiring everything up would be very costly.
The preferred solution would not require a server backend of any kind and would work with a list of wifi access points and their corresponding locations.
I wouldn't know about 1 and 2. But if you would implement such a thing, turn it around to save a lot of trouble: create your own free-of-charge wifi network, and let the network determine the location, either based on triangulation, or just based on the currently associated access point. Make their signal weak so you have one audible access point per room. Let the app ask a server in what room he appears to be. This will also work for any other mobile/pda/laptop.
As for other ideas: You could use bluetooth to do somewhat the same as you're planning for wifi. You can't do everything with bluetooth, but listing devices seems to be one possibility. So just put a bluetooth device in every room. Bluetooth range is limited by definition.
Another one would be to use the microphone in conjunction with a high pitched sound which identifies the room, but that would cause trouble with dogs (for blind people), attract bats, and repel mice at the same time. Better focus on an RF based solution ;-)
You can also check out Navizon's indoor positioning system:
http://www.navizon.com/product-navizon-indoor-triangulation-system
Their system is able to locate iPhones by using the WiFi signals transmitted by the device and doesn't require an app to run on the phone to locate it. It can locate any other WiFi enabled device for that matter.
Check out wirelesswerx.com They seem to be doing indoor location using Bluetooth and it looks like they can do permanent install or temporary for events.
What's the deal with iPhone's GPS? I never get a good reading when i'm in my office building, or in my room. What really ticks it! and what doesn't? Please help me understand the assisted GPS science.
If I'm not mistaken, the gps tries to pinpoint your position using three methods:
1. Satellite
2. Mobile network
3. Wi-fi networks
So if you don't have a good reading, then probably one or more of these methods cannot be used properly in your area. For instance, satellite will not always work that well in buildings with thick walls and ceilings.
Assisted GPS means that it may have it's location from different sources than GPS satellites, for instance known wifi hotspots, or GSM masts. However these sources are less accurate the true GPS.
Claus
For the actual GPS in your iphone to get a good position, it has to be in direct sight of the GPS satellites. It cannot do that inside a building. So if you are inside you are not going to get the best position from the iphone. It can give you a position using other methods such as the cell phone network and public wi-fi networks, but these positions aren't as accurate as the real GPS position.
Here is an article that explains the GPS system:
http://en.wikipedia.org/wiki/Gps
Depends on whose definition of Assisted GPS.
True 'assisted GPS' means the GPS receiver uses a known initial position, from the cell tower location, to bootstrap the GPS position calculations. If you know where you are it's much quicker for the position solution to lock to the signal - that's why GPS take so long to find first fix compared to updating.
Some APIs use assisted GPS as shorthand for alternate location services where if GPS is not available, is disabled, or would use too much battery power it will supply a lower grade position based on cell tower triangulation or other methods.
There are many answers I found in WWDC 2010 – Session 115 - Using Core Location in iOS 4.
Very advised.
I was wondering what amount of time is required to convey information regarding the tilt and position (not gps) of one particular iphone to another. Could 2 iphones send and receive this information simultaneously? What about 3 iphones? I'm interested in an application that is able to simultaneously send and receive and make conditional decisions based on this information received all within a half a second-ish.
Any shot this is possible? If so, is bluetooth or wifi better?
Thanks a ton,
Jake
This is currently not possible without an intermediate server. (Without a jailbreak, which would make it possible, but extremely difficult)
I'm assuming your purpose is gaming, in which case, the latency associated with a trip to a server and back over a cellular data network, is likely to take too long for any satisfactory gaming experience. I don't believe it would be within half a second.
This will be possible via Bluetooth in the upcoming 3.0 iPhone software, but that is still under NDA, so you are not likely to be able to get any reliable performance numbers until it is released. If I were guessing, I would certainly guess that the latency associated with a direct Bluetooth connection would be FAR under half a second.
All you've got as an option right now is Wi-Fi or the Cell Network. If you use Bonjour over Wi-Fi, you'd have latencies in the milliseconds, but all the phones would have to be connected to the same access point. Take a look at the WiTap example.
It is definitely possible, you'd want to connect your peers over WiFi for best performance and reliability, but Bluetooth would be ok as long as your data packets were constrained to small sizes (< 1k). Check out this documentation and sample code to see how to access UIAccelerometer:
http://developer.apple.com/iphone/library/documentation/UIKit/Reference/UIAccelerometer_Class/Reference/UIAccelerometer.html
http://developer.apple.com/iphone/library/samplecode/AccelerometerGraph/index.html#//apple_ref/doc/uid/DTS40007410
The trick is that the update frequency is controlled in part by the systems needs, so there may be a window (while the system is attempting to update device orientation) wherein your application receives no updates.