On Wed, 2008-07-16 at 21:38 +0200, Alasal wrote: > 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.
More specific: the GPS signal level drops by -20dBm, i.e. factor 100. Signal strength of a GPS satellite above your head is around -127dBm. Needed strength for a first fix is -145dBm with a minimum of three satellites. Once the GPS chip has a fix, it can operate at signal levels of -157dBm, thus making it possible to operate while there is data transfer from/to the SD card. > 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) The FR's GPS performance is definitely top notch without the SD card. > 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 it's first fix. After that you will be able to read the > SD card again. You can always read the SD card. As said above the GPS signal temporarily drops by -20dBm during i/o. The kernel patch is a pragmatic and well working solution and should not effect daily use. > 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) With the help of AGPS you can shorten it probably to 15 seconds. _______________________________________________ Openmoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community