GTA02 GPS Problems
The GTA02 has a problem with signals to the SD card causing interference to the GPS receiver, effectivly reducing its sensitivity by 20dB and making it slow or impossible to get an initial fix.
There has been much discussion of this on the mailing lists. On Wed, Jul 16, 2008 at 12:38 PM, Alasal <email@example.com> posted a summary of everything related to the GPS problem to the openmoko-community list.
- What is the problem?
- The Openmoko Freerunner have a long TTFF with the SD card in the phone. So it takes a long time (10min+) before you get your first GPS data.
- Does the people of Openmoko know the problem?
- Do they work on the problem?
- Yes, they are actively searching for a solution.
- What is TTFF?
- This is the time to first fix of the GPS. This is the time the GPS has needed to get the first clue on where you are on planet earth. So you have to do this only once. After you have a FF (first fix), you can get more fixes without any problems with the SD card in the phone.
- So if we have a first fix, the SD card isn't blocking the GPS anymore?
- yes, the SD card isn't blocking the GPS if we have a first fix. (Some people even claim it's more stable)
- Does they have a solution?
- yes. Their is already a highly alpha software workaround. The software just disables the SD card when the GPS tries to get it's first fix They are also examine a hardware solution.
- Do we have to return our Freerunners to Openmoko?
- Probably not, because the software workaround should work too.
- But we can't read of the SD card when the GPS is on?
- Wrong, you will be able to read the SD card when the GPS is on. You will probably not be able to read the SD card when you're starting the GPS (appr. 30 sec), because the GPS will only block the SD card when it's searching its first fix. After that you will be able to read the SD card again.
- Is there a better software solution?
- Maybe. From reading the mailing list, I have understood that half the Openmoko team is looking into this bug. All this information is only 1 - 2 days old and the bug is also young, so I suspect they can finetune the software workaround and make it only slowdown the SD card or even better.
- Did Openmoko test the GPS with a SD card in it?
- Whey didn't they find it while testing the Freerunner?
- Because they have to do the tests with a fake GPS signal and with that signal it worked. (In a fab you haven't a decent GPS signal) They already have modified the test, so it correspond the GPS signal better.
Summary of the summary:
You will be able to use the SD card in the same time of the GPS except for the first appr 30 seconds. (And that's the worst case, because maybe Openmoko can find better hacks/fixes)