Use Android GPS to detect and connect with other phones

Question

So I asked something similar yesterday and did receive an answer to my question, however I don't really think I asked it correctly and therefore didn't receive the exact information I needed.

I'm in search of an API, some open source code, or even just a way that someone else has achieved this on the Android. I'm making an app that needs to find all other Android devices within a specified radius. For example, when you open your Android Google Maps App, and you search for say "Restaurants [ZipCode]", it uses a radius modified from your zip code and finds all of those places. The GPS gets YOUR location, and maps uses that information to find restaurants within an address close to that passed in location.

Instead, I want to be able to use the GPS to find my location (as it can now easily), but instead of finding things on a map (which is already built in), I want to be able to find other GPS enabled Android phones. I get that they will have to be broadcasting their GPS signal at the same time as well (since they don't have their data stored with some sort of central database as a restaurant would). However, I don't just want to FIND these phones, I want to send/receive data from these phones (with correct permissions obviously).

Now, I've found things like the Bump API. However, BUMP uses the phones sensors to spark this search. So basically, if you "bump" your phone with another and have the app running, it will THEN go ahead and use GPS to find the location of the other phone you just bumped with and exchange data between them. This is like EXACTLY what I want to do however in their API, they do not provide the functionality to just say, "Hey, give me all phones within a mile from me."

I've also found API's that can do exactly what I need but they have to be on the same Bluetooth range or on the same Wi-Fi network, which doesn't suit what I need at all.

Do you guys know of anything that can fit exactly what I need that already exists? Or a way to maybe modify Bump API (if you've done it), to not have to use the phone sensors and find phone information directly through GPS for phones around you? Or is there something that exists over a 3g/4g network instead of only wi-fi/Bluetooth?

Thanks guys.

Answer 1

To do this via GPS, you would have to have all the phones frequently posting their locations to a network server, which could then inform them of others nearby.

Needless to say this would be opt-in only!

And it may have negative consequences for battery life, unless you make it update infrequently, which may limit its usability.

The advantage of having an explicit trigger action to both phones is that they only need to query the GPS and inform the server to find each other by location when they've both been triggered.

Answer 2

Instead of frequently posting locations to an external server, couldn't the GPS realize other things broadcasting a GPS signal at a very specific time and send/receive data from them?

The only things that are "broadcasting a GPS signal" are satellites.

We would like to accomplish this without the use of an external server.

You have no choice but to use an external server, whether you like it or not, both for discovery and for later communication.

Do you guys know of anything that can fit exactly what I need that already exists?

Foursquare, Google Latitude, Yahoo Fire Eagle, and so on.