Sat Nav without WiFi

[jk000]

I've never understood why I can be in my house, link to my wireless network and see my position on the satnav application. Then as soon as I venture outdoors without a WiFi connection my position won't change. It's probably been spoken about for ages on here, I haven't been on this sit for ages, sorry. It's really annoying? Why would you want satnav if you have to be wirelessly connected all the time?

[Mr G]

You do NEED a satelite fix too you know mate.

[Gizmoratty]

The phone will automatically assume your GPS position is in the last place it had a satellite connection

Make sure you are achieving a sat. connection before you try using the GPS funtions

Depending on your version of the maps application, the little radar dish icon in the bottom right hand corner of the screen will either have 3 little green dots next to it or a few little lines coming from it - Each indicating a satellite connection

[jk000]

Yeah I do get the green icon etc...I can get a connection when I'm connected wirelessly to a network. I'm talking about when I'm miles away from a connection no connection can be found, then i want to know, why won't it locate my new position?

[Nokia N95]

Assuming you have the new version of Nokia Maps and you're connected to the satellites... press 0 for your current GPS location.

[andykn]

From the maps application on the phone, go to Options > View > Satellite info.

You should get some hollow bars first, then at least three of them should go solid. Then you have a lock. You need to have the slider open and the GPS receiver, located under the # key, needs line of sight to the sky.

If the GPS hasn't locked before, this can take up to 10 minutes. Once it has locked once subsequent locks are much quicker.

[flamesong]

From what I understand, the implementation of A-GPS relies on a data connection to assist the initial positioning. As I don't want to accidentally use packet data from my network I have configured the phone only to connect via wireless networks. Consequently, I get a quick position at home (when I know exactly where I am!) and often cannot get a position when I'm out - even away from buildings on a clear day.

If I use my Bluetooth GPS I hardly get any positioning problems anywhere.

[Rusty]

The A-GPS setting is separate to the rest of the phones settings, even with the packet data default access point set to 'none' A-GPS will make a connection to your network without telling you.

Might be worth checking your logs before and after using GPS and see if any packet data is exchange (will only be a small amount)

[andykn]

Originally Posted by flamesong

From what I understand, the implementation of A-GPS relies on a data connection to assist the initial positioning. As I don't want to accidentally use packet data from my network I have configured the phone only to connect via wireless networks. Consequently, I get a quick position at home (when I know exactly where I am!) and often cannot get a position when I'm out - even away from buildings on a clear day.

If I use my Bluetooth GPS I hardly get any positioning problems anywhere.

You need to find out why its taking so long outdoors. From the maps application on the phone, go to Options > View > Satellite info and see how it progresses.

I don't use AGPS as I'm on a poor tariff for data but still get quick lock times. It took less than two minutes to lock in the UK from a last lock in Brisbane.

[flamesong]

I think this is where I got my infoemation from:

Wikipedia
Assisted GPS - Wikipedia, the free encyclopedia

GPS is a satellite based positioning system. Assisted GPS, or A-GPS was introduced to enhance performance. The development of A-GPS was accelerated by the U.S. FCC's E911 mandate requiring the position of a cell phone to be available to emergency call dispatchers.

Conventional GPS then had difficulty providing reliable positions in poor signal conditions. For example when surrounded by tall buildings (as a result of multipath), or when the satellite signals are weakened by being indoors or under trees. Some newer receivers fare better.

In addition, when first turned on in these conditions, some non-A-GPS units may not be able to download the almanac and ephemeris information from the GPS satellites, rendering them unable to function until a clear signal can be received continuously for up to one minute.

An A-GPS receiver can address these problems in several ways, using an Assistance Server:

The Assistance Server can locate the phone roughly by what cell site it is connected to on the cellular network.

The Assistance Server has a good satellite signal, and lots of computation power, so it can compare fragmentary signals relayed to it by cell phones, with the satellite signal it receives directly, and then inform the cell phone or emergency services of the cell phone's position.

It can supply orbital data for the GPS satellites to the cell phone, enabling the cell phone to lock to the satellites when it otherwise could not, and autonomously calculate its position.

It can have better knowledge of ionospheric conditions and other errors affecting the GPS signal than the cell phone alone, enabling more precise calculation of position. (See also Wide Area Augmentation System)
Some A-GPS solutions require an active connection to a cell phone (or other data) network to function, in others it simply makes positioning faster and more accurate, but is not required.

As an additional benefit, it can reduce both the amount of CPU and programming required for a GPS Phone by offloading most of the work onto the assistance server. (This is not a large amount for a basic GPS - many early GPSs ran on 386/16 or similar hardware).

High Sensitivity GPS is an allied technology, that addresses some of the same issues in a way that does not require additional infrastructure. It notably cannot provide instant fixes when the phone has been off for some time, that some forms of A-GPS can.