GPS not working... at sea in Pacific

Question

GPS not working... at sea in Pacific

Hi all,

I owned a 3G for over a year and now I've just bought a 3Gs. I am onboard a cruise ship where I work as a comminications Officer so I know a thing or two about GPS. My phone worked OK back in the UK and GPS seemed to be working just fine. However since I arrived on my ship I've been unable to get a GPS fix. When at sea there is no phone network or Wi-Fi etc. and I cannot get any GPS, also my colleague has a 3G and he's having the same issues. When we arrived in port last night and I acquired a mobile phone network but we still had the same issue. All of the GPS units on the bridge of my ship are working normally so there is no problem with our position in regards to receiving signals.

Yes my phone is turned on and location settings are on. I have an app called Motion GPS and in that app it just says 'No signal' from Satellites. I've tried the compass as well and no joy.

Message was edited by: British Bulldog

iPhone 3Gs, iPhone OS 3.1.3

Posted on May 18, 2010 6:08 PM

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Answer 1

Tamara

Level 6

13,744 points

May 21, 2010 5:09 AM in response to British Bulldog

I just put my phone in airplane mode and went outside. I have an app on the phone called Checkup that tests various functions. I was able to get my gps coordinates after a few minutes of being out in the open.

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Answer 2

ChrisJ4203

Level 10

236,309 points

May 18, 2010 6:11 PM in response to British Bulldog

Do you have the phone in airplane mode by chance, to prevent data? If the phone is in airplane mode the GPS is turned off.

If not, you may need to restart or reset the phone since you have changed wireless locations. It may take a while for that to acquire the A-GPS it gets from the wirless tower triangulation.

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Answer 3

DaVBMan

Level 6

9,292 points

May 18, 2010 6:30 PM in response to British Bulldog

As the other poster elluded to, the iPhone (as with most cell devices that have GPS) use A-GPS. Most of the processing is done by your carrier (The A stands for assisted). Without it, the phone can take quite some time to actually get a fix on sats and also process the data. You can read up on A-GPS at Wikipedia to understand how it is the power of the network you are on that makes GPS function faster and better on a cell device. It is not the same thing as GPS devices you have that are dedicated GPS units.

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Answer 4

May 18, 2010 6:44 PM in response to DaVBMan

Hi,

I do know what A-GPS is, like I said I work on the bridge of a ship, and deal with all types of GPS including A-GPS, D-GPS etc. It works like Differential GPS (D-GPS) using signals from available sources if they are there, however when the mobile phone networks are not available it should take the location directly from satellites alone, but it's not the case. I've tried for long periods of time with no success. My colleague also tried last night whilst stargazing and he said he couldn't get a fix.

And no my phone is not in Airplane mode.

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Answer 5

DaVBMan

Level 6

9,292 points

May 18, 2010 6:46 PM in response to British Bulldog

Yes it should eventually get a fix. And I have heard it takes a long time with no network. How long is long, sorry I don't know. Just stating what I have seen reported here by those either out at sea as well, or out in the middle of nowhere hiking.

I have not looked into the manual about the matter. Have you happened to read the manual to see what is says?

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Answer 6

DaVBMan

Level 6

9,292 points

May 18, 2010 6:49 PM in response to DaVBMan

One thing I did read, ensure your time and timezone is right, it uses this info with info from sats. If your time and timezone is wrong (which could happen if you are not on a network and crossed timezones) it could mess it all up.

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Answer 7

May 20, 2010 10:54 PM in response to DaVBMan

Hi again, update. Time is correct on my phone, I have tried on more occasions to get the GPS working but no luck. I waited for 35 minutes to 'give it time' to connect to teh satellites but still nothing. I was on the top deck with completely clear unobsructed view and nothing above me. In fact the deck where the GPS units are situated on the ship, and still nothing, no change in the phone's GPS coordinates which are still from my home in the UK!

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Answer 8

May 20, 2010 11:54 PM in response to British Bulldog

I just went out on deck, I connected to the ship's WiFi connection and immediately the GPS coordinates appeared! So it's not a true GPS device, only using a data service such as Wi-Fi or cell/mobile phone data services to get a fix. I have been trying to get a fix with proper GPS satellites for almost two weeks and now with wi-fi hey presto. It's not 'assisted GPS (A-GPS)' at all, it's data assisted GPS. I'm pretty dissapointed with that.

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Answer 9

wjosten

Level 10

95,369 points

May 21, 2010 2:08 AM in response to British Bulldog

The iphone's GPS chip will work just fine without a data or cellular connection. However, without some sort of mapping software available, either through a dedicated GPS application or through that data connection...well there is nothing to use to show your location. I suspect that's your experience. I've seen experiments using the iphone with GPS turned on, packed in a watertight case, towed behind a ship, bobbing in & out of the water, and the resulting GPS track was almost perfectly recorded. Many GPS receivers fail to work at all when used right at the surface of the ocean.

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Answer 10

May 21, 2010 4:35 AM in response to Tamara

I was using an app called Motion GPS, and I was just looking for the coordinates to show up, I also used the Compass which is supposed to show my current location in GPS coordinates. It just showed the last coordinates from before I left my home, (the last time I used it when it had a data feed) I wasn't expecting any maps to show up because there is no data feed to allow them to be downloaded. I work with (proper) marine GPS all day long, and I work with maritime maps etc. in my job so I'm no novice to this kind of thing. The GPS simply does not work unless it has a data feed. I tried many different locations around the ship, different decks for height etc. and nothing. the message was 'Unable to find satellites' Then I connected to the Wi-Fi and hey presto, immediately it says in Satellites 'Good signal' and updated my coordinates.

I'd like others to try it, turn off your data feeds, both Wi-Fi and Cell phone and try to get a fix, it wont work.

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Answer 11

Ingo2711

Level 10

80,307 points

May 21, 2010 5:58 AM in response to Tamara

I just did the same, but my results are somehow different:
First I tried Checkup with cellular service/location service on. Within seconds I got the GPS coordinates.
After that I switched to Airplane mode, left location service activated and got the same GPS coordinates. But when I deactivated location service on the phone as well, I got the dialog box asking me to switch on location services, which I denied and got no coordinates after that at all.
I tried the same procedure with MotionGPSlite with the same results, no signal without Cellular or WiFi network. It seems that location services is caching the last info and providing it to other apps.

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Answer 12

Tamara

Level 6

13,744 points

May 21, 2010 4:04 AM in response to British Bulldog

Just to clarify, in your 35 minute test, were you waiting for maps to appear?

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