Thread: GPS reception in tunnels

Originally Posted by mikehzz

If you have assisted gps like in smart phones then the gps still works in a tunnel if you have mobile reception. It uses both satellite reception and mobile phone tower triangulation as inputs. If one drops out it still gets info from the other.

My iPhone with Tom Tom doesn't work....umm not that I have checked reception

Its an option you have to turn on as it can use data download and cost a bit

Originally Posted by Brian Hjelm

Oh, Diana, do I detect just a little sarcasm there. Strike a little traffic getting between POW & home?

How is life in Mohammed Alley? Are you still the only lady in the neighbourhood who doesn't wear a bag over her head?

I've stopped using the Middle-Eastern Distributor and the tinting of the D4 allows me to exit Mecca without having the Religous Police stopping me from driving. They have somehow modified my D4's radio so it does uncommanded channel changes from ABC Classic to SBS so I still get the Imam's teaching.

In shal lah Land Rover can fix the radio.

Originally Posted by THE BOOGER

Its an option you have to turn on as it can use data download and cost a bit

No not correct. The data download is just for on the go maps from places like google if you haven't stored them on the phone. The triangulation doesn't use data but is part of normal background communication with the cellular network. I triple checked it for an overseas trip.

Originally Posted by mikehzz

If you have assisted gps like in smart phones then the gps still works in a tunnel if you have mobile reception. It uses both satellite reception and mobile phone tower triangulation as inputs. If one drops out it still gets info from the other.

this is incorrect
a-gps helps you get a fix quicker

[ame="http://en.wikipedia.org/wiki/Assisted_GPS"]Assisted GPS - Wikipedia, the free encyclopedia[/ame]
Assisted GPS, generally abbreviated as A-GPS or aGPS, is a system which can under certain conditions improve the startup performance, or time-to-first-fix (TTFF), of a GPS satellite-based positioning system.

Inertial navigation systems are also coming down in price. For tunnel use they will just measure the acceleration you subject the system to and determine changes in velocity and turns to determine your speed and location relative to your last known speed and location.

Originally Posted by Eevo

this is incorrect
a-gps helps you get a fix quicker

Assisted GPS - Wikipedia, the free encyclopedia
Assisted GPS, generally abbreviated as A-GPS or aGPS, is a system which can under certain conditions improve the startup performance, or time-to-first-fix (TTFF), of a GPS satellite-based positioning system.

I've tested mine against normal gps all over the place from the city to the deserts and overseas. My smart phone gives me a fix indoors where the normal gps doesn't. The smart phone works better in the city between tall buildings where the normal can lose satellites. The normal gps is better by far out in the country. Cloudy weather can make the phone drop gps signal when there is no phone coverage. I think the phone has a poor gps antenna. Without cell coverage, the phone can take forever to find satellites and then lose them quite easily. A 3g ipad is the best gps I've used, it must have a better antenna because it seems to work well everywhere, gets a quick fix due to the agps in cell tower coverage and holds it. I've found it gets a pretty quick fix out in the desert too and the screen is great.

Oh and my data has been turned off. I checked with the provider to make sure that this wouldn't affect the gps. Perhaps it may in places where they may charge for everything like the US. I think you pay for incoming calls over there...I may be wrong but that's what I heard.

Originally Posted by Lotz-A-Landies

If Governments and tunnel owners worldwide could get together with manufacturers of GPS receivers I'm sure it could be solved.

no thanks, I do not want to pay for that thing too...