GPS Accuracy (3GS)

adrian3221 · 11-07-2009, 8:33 PM

How accurate do people find the GPS using Google maps on the 3GS? Even in Central London it always seems to be a street or two off. Bit disappointed with it.

thelurch · 11-07-2009, 8:39 PM

we actually used the maps function on my wifes 3G today with the GPS on coming back from Devon and it was always a couple of roads away or in a field. Its the first time we've used it and were surprised it was so inacurate

Rich9600 · 11-07-2009, 8:42 PM

For me, up in Cumbria, it is good to a metre or so.
I was sat in my garden earlier this week, I tried it and it was absolutely spot on.

RedBull · 11-07-2009, 8:47 PM

If I walk out the front door it'll locate me on my driveway. Very impressed

a l e x · 11-07-2009, 8:49 PM

Seems pretty accurate here in yorkshire too. Pretty much spot on most of the time.

loz · 11-07-2009, 9:27 PM

For the first time I was using google maps today to navigate round SW London, my wife was driving her car and we didn't have our sat nav with us.

I found it extremely accurate, and wondered if it was using any intelligence to place us on the road rather than in a park or something... we were always on a road and it was very interesting watching it tracking us precisely along the road.

Having said that, when I have played with it at home, I have also noticed it place me on the golf course behind our house, rather than in our house where I am...

Desmo · 11-07-2009, 9:28 PM

I used it whilst travelling in a car today (not driving) and it had us in the exact spot on the road, although would deviate across lanes a little. Accurate enough I'd say.

adrian3221 · 12-07-2009, 8:30 AM

I restored the phone today and it does now seem to be more accurate as it has now found my home location for the first time.

RobM · 12-07-2009, 3:37 PM

Quote:

Originally Posted by loz

Having said that, when I have played with it at home, I have also noticed it place me on the golf course behind our house, rather than in our house where I am...

That's probably because you'll be using mobile cell triangulation at this point, not GPS. Being satellite based, GPS requires a clear view of the sky in order to pick up a signal. But the iPhone will also use the mobile network to locate you (cell triangulation) but it's not as accurate.

The difference in Google Maps is you get a solid blue dot when you're connected definitely and totally accurately (GPS, WiFi) and you'll get a blue dot with a light blue circle around it when it's a rough and inaccurate location.

loz · 12-07-2009, 5:52 PM

Quote:

Originally Posted by RobM83

That's probably because you'll be using mobile cell triangulation at this point, not GPS. Being satellite based, GPS requires a clear view of the sky in order to pick up a signal. But the iPhone will also use the mobile network to locate you (cell triangulation) but it's not as accurate.

The difference in Google Maps is you get a solid blue dot when you're connected definitely and totally accurately (GPS, WiFi) and you'll get a blue dot with a light blue circle around it when it's a rough and inaccurate location.

yes, I know that.

I didn't mean physically inside my house... I just meant at home. Sorry, I wasn't clear.

But I was using playing with it today whilst in the car in the drive. What was interesting is that even though I wasn't moving, my position on google maps was. Presumably as it gradually tried to refine the position as it acquired more satellites or something. At one point it was spot on - on satellite view, there I was sat in my car

Except the photo was of my old car

Then it decided to finally place me about 10mtrs into the road. But not bad

tdenson · 12-07-2009, 6:40 PM

Quote:

Originally Posted by adrian3221

How accurate do people find the GPS using Google maps on the 3GS? Even in Central London it always seems to be a street or two off. Bit disappointed with it.

Not quite sure why you say "even in Central London". The point about that is that I wouldn't be surprised if it were inaccurate in London due to the canyon effect (tall buildings). The point about Global Positioning System is that it is global, there is no better signal in places of high population in the way that cell signals work. As another poster has said, I suspect you don't actually have a GPS signal as evidenced by the pulsating blue dot. For me, I always find the GPS signal pretty accurate, no more than a street width in error.

adrian3221 · 12-07-2009, 7:03 PM

Quote:

Originally Posted by RobM83

That's probably because you'll be using mobile cell triangulation at this point, not GPS. Being satellite based, GPS requires a clear view of the sky in order to pick up a signal. But the iPhone will also use the mobile network to locate you (cell triangulation) but it's not as accurate.

I didnt know this, just tried using it outside my house and bingo!

syman · 12-07-2009, 10:02 PM

In Cambridge absolutely spot on, same in Bedfordshire/Hertfordshire with O2, T-mobile perfect in Cambridge but about a mile off in Biggleswade/Hertfordshire - T-mobiles cell triangulation obviously not as good in these areas.

Rich9600 · 13-07-2009, 7:27 AM

When I first open Google maps or I am inside (no satellite signal locked) I'm shown to be at the centre of a circle quite a long way off. However, the circle always covers my location. Soon it triangulates a bit better and drops down to a radius of around 50 yards, usually centred on the road outside when I'm at home.

As soon as I get a satellite signal the dot is good to a few metres! If I manage to get a satellite signal inside the location can fluctuate due to the weak signal.
I have had GPS equipped mobile phones before and so far my 3G S is the quickest I've had to get a satellite lock and seems very accurate.

Previous phones have not triangulated using the mobile phone network, this is a nice feature and I think it is useful. Occasionally the satellite signal gets lost, especially in cities due the previously mentioned canyon effect.
Can the system locate you by WiFi connection and the proximity to the associated telephone exchange etc?

In cars Sat Navs are usually best located on the dashboard, even then some cars have a windscreen that effectively blocks much of the signal. I have also, with previous systems, lost connection in heavily forested areas and in heavy rain using other systems.

Google maps will also be limited in remote areas by the data connection. The ability to get the get the map data will surely effect the refresh rate of the location, especially when moving quickly in a car. Locally to me I occasionally get 3G but mostly work of Edge (E) and GPRS (o), or even loose the signal completely...

tdenson · 13-07-2009, 8:18 AM

Quote:

Originally Posted by Rich9600

I have had GPS equipped mobile phones before and so far my 3G S is the quickest I've had to get a satellite lock and seems very accurate.

.

Part of the reason for this is that the iPhone implementation is what is known as Assisted GPS (agps) whereby the phone uses the cellular network to acquire information to tell it approximately where the satellites are, making the GPS fix quicker.

Rich9600 · 13-07-2009, 8:41 AM

Quote:

Originally Posted by tdenson

Part of the reason for this is that the iPhone implementation is what is known as Assisted GPS (agps) whereby the phone uses the cellular network to acquire information to tell it approximately where the satellites are, making the GPS fix quicker.

My previous two were both Assisted GPS, but still not quite as quick as the iPhone.

The previous devices were HTC devices running Windows Mobile 6.0. This OS is used on many devices and I wonder if the lack of system diversity of the Apple OS makes it quicker. Less options to worry about and so it can be simpler.

Also 600MHz v 400MHz for the processors.