> -----Original Message----- > From: [EMAIL PROTECTED] [mailto:community- > [EMAIL PROTECTED] On Behalf Of Joerg Reisenweber > Sent: Tuesday, July 15, 2008 4:29 PM > To: community@lists.openmoko.org > Cc: thomasg > Subject: Re: Reason for GPS problems found! > > Am Di 15. Juli 2008 schrieb thomasg: > > Hi ppl, > > > > I write this to community, not to devel or owners because everyone > > should > > know: > > *sbeh*, one of the people in #neo1973-germany IRC-channel found the > > reason for the GPS problems. > > The problem only occurs if a SD card is set in. Doesn't matter if > it's > > mounted or in use, it just has to sit in the socket. > > The TTFF went from no fix at all to TTFF 120 seconds indoor(!!!), and > > about 40 seconds outdoor. > > Two other people could verify this with about the same results. > > We'll do more tests later, but for now we surely know what's causing > > the problem (and it seems to be a EMC problem). > > > > First results show at the same devices, even outdoor, that there is > no > > fix in over 400 seconds with SD card, the signal seems to be at least > > 10 to 20 dB worse (so bad, that most satellites don't even appear). > > > > Testresults from other people appreciated. > > > > So we can assume this is pretty confirmed by quite some reports now. > Thanks to community for the awesome help on this! > Special thanks to *sbeh* for finding this. Please mail me directly ;- > )!! > > We did quite some tests on this as fast as we could (and I never > assumed we could be *that* fast), and it seems we found the root cause > of the problem. > ALL THIS IS PRELIMINARY INFO! Due to further tests to confirm. > Just to let you all know we're on it, and please stop thinking about > shielding the SDcard with tin foil or relocating internal gps-antenna. > It won't probably help. > > The good news: *IF* all pans out, there's (or soon will be) a new > kernel at Andy branch that stops SD-card clock when SDcard is idle. We > hope this will almost cure the problem, at least reduce it to sth like > "you can't GPS while watching video from SD" or the like (hope you can > cope with that ;). > We're about to verify a hw-fix so you could even watch video and still > have GPS positioning during that. > > > Please stay tuned and be patient, we'll come up with news *really > soon*. > And *please* don't try weird reworks and maybe break your FR by doing > so > ;-) ;-) ;-) ;-) ;-) ;-) ;-) ;-) ;-) ;-) ;-) ;-) ;-) ;-) ;-) ;-) ;-) > > cheers > jOERG
Thanks for all this fast testing and great work. I was worried when there was silence. I hope for both a hardware and software fix, because if the solution is just a patch to turn off the SD while getting a fix, it may work but I feel that I have inferior hardware...even if it's on a psychological level only. With truly fixing the root cause of the interference via hardware then I know that even if the GPS signal gets faint in a condo canyon or tunnel the SD card won't hinder GPS operation. That way when I take the FR into the Houston tunnels [1] I won't be cursing the SD card when it's really the impossible chance of getting a signal in the basement of a skyscraper of downtown Houston. ;-) [1] http://en.wikipedia.org/wiki/Houston_Downtown_Tunnel_System -Robert _______________________________________________ Openmoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
