What GPS do not use GPS satellite?

Huh?
You either use GPS or you don't.
GPS stands for Geo Positioning Satellite system.
So if you "reach places that [you] cannot connect to satellite", step outside, so that you can connect to satellite.
GPS does not work indoors or underground. It requires line-of-sight with at least a handful of GPS satellites.

 

Your rough location can be gained from what cell towers you are connected to, but this is not nearly as accurate as gps

 

GPS is GPS and the most accurate way to know where you are anywhere on the planet as long as you can see four of the thirty-ish satellites. Three satellites can be considered a signal still, but less accurate.

Saying "I can use the handphone data plan for gps" is the issue. You cannot have GPS without the satellites. But you can get cell tower location and known wifi positions to randomly guess with general and unreliable certainty.

This is how GPS works: GPS, relativity, and nuclear detection - YouTube

 

Apps like google maps and Waze will guess your current location when they lose a GPS signal. They will work off the last known GPS signal and then guess based on wifi, cell tower, etc. Not accurate at all.

But a dedicated app that only uses non-GPS sources for location data? Can't think of one. Sorry.

 

Almost any app that uses your location will use your rough location from cell towers when you have your GPS radio off.

There shouldn't be any new apps needed, just shut off your GPS radio

 

Open up your map application with your gps radio on.

It'll get a lock and display where you are with the little triangle.

Now close maps, shut off your GPS, and open it back up.

It won't get a lock, and you'll have a huge blue circle around the little triangle. That's the rough location its pinned you to based on your cell towers.

(Make sure WiFi is off during this test)

 

I'm confused. My brain hurts.

 

Your location may be off by as much as a mile if you don't use satellites.

 

Sometimes my location can be off by as much as 2,500 km if I don't use satellites.

Friends, use satellites, you know it makes sense! :thumb:

 

In my daily experience (civilian!) GPS positioning is accurate within 10 metres/30 feet, while cell tower triangulation is off by between 400 and 800 metres/a quarter to half a mile.

US military GPS is accurate up to 6 inches, in 3 axis. 'They' can land e.g. FA-18 fighter jets "hands off"

 

I think the problem that the OP needs to solve is why his phone isn't locking on to the GPS satellites. Unless you're driving around underground, your phone should be lock onto GPS satellites. My LG Optimus S used to have problems locking onto GPS until I did an OS update. Now I never have that problem.

 

The S4 should have GLONASS as well as GPS, so if you can see the sky there ought not to be a problem getting a location.

 

I've found that phones are much better at getting a good lock on GPS signals than standalone GPS units I've owned. Granted my GPS units were old, but I think phone can combine a lot more data, whereas a standalone GPS can only use GPS signals. Have you tried your phone's GPS when your standalone GPS failed?

Edit: To elaborate on that...for a standalone GPS to get a lock it needs at least 4 VERY good satellite signals, and some need more (and some can get an approximate location on 3 very good signals). GPS signals don't carry location data; they identify the location of the satellite they come from and tell what time it is, down to the millisecond, and the GPS unit then does a bunch of crazy math based on the speed of light and the satellite's orbit and such to calculate how long it took the signal to arrive; by comparing that time data with the data from other satellites it can figure out your location. A phone can pull cell tower triangulation to get the general area and more importantly a better idea of exactly what time it is, severely reducing the volume of satellite data necessary as well as the time it takes to locate. That's all theory; I don't know if that's how the technology is actually designed, but it would explain the much better performance I see in phones.

 

Phones use assisted GPS - hence the ability to get a mostly accurate position with only three satellites. Assisted GPS takes the triangulation and combines it with wifi/cell data to pinpoint you.

For some reason GPS devices don't build in wifi and therefore require four satellites.

 

It will use both. Nothing for you to select.

 

What is AGPS How Does it Work

As stated in the S4 spec, it uses AGPS and also has GLONASS.

When 'GPS' is active on your device, the original GPS and the recently added GLONASS search for their respective satellites, assisted by AGPS.

 

TBH it doesn't really matter if the GPS can't receive satellites in a tunnel. You go in one end, you come out the other, it's rather difficult to get lost.

What's covered areas? Something like an underground car park? Turn-by-turn directions aren't really going to help you here anyway.

As soon as you're out in the open, the GPS receives the satellite signals and you're back in business.