Re: GPS time synch
Michael 'Mickey' Lauer [EMAIL PROTECTED] writes: On Mon, Feb 19, 2007 at 11:47:23PM +1100, Mark Chandler wrote: Would it be possible to keep the Neo's internal clock accurate using time stamps from GPS information? yes. That is only during GPS being powered up, of course. We probably don't want it to be powered unconditionally, since it drains quite some power. Out of curiosity, how bad is the GPS power drain? There are applications I would like (such as automatically turning the ringer back on when the phone is inside my home -- I always forget to do that and miss calls) that require location information at reasonably frequent intervals... Perry ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: GPS time synch
On 2/20/07, Michael 'Mickey' Lauer [EMAIL PROTECTED] wrote: Harald Welte wrote: On Mon, Feb 19, 2007 at 11:47:23PM +1100, Mark Chandler wrote: Would it be possible to keep the Neo's internal clock accurate using time stamps from GPS information? yes. That is only during GPS being powered up, of course. We probably don't want it to be powered unconditionally, since it drains quite some power. If it is cheap it might be an idea to grab the time everything GPS is used. See also http://wiki.openmoko.org/wiki/Wishlist:Set_Local_Time /Ole ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: GPS time synch
Perry E. Metzger wrote: Michael 'Mickey' Lauer [EMAIL PROTECTED] writes: On Mon, Feb 19, 2007 at 11:47:23PM +1100, Mark Chandler wrote: Would it be possible to keep the Neo's internal clock accurate using time stamps from GPS information? yes. That is only during GPS being powered up, of course. We probably don't want it to be powered unconditionally, since it drains quite some power. Out of curiosity, how bad is the GPS power drain? There are applications I would like (such as automatically turning the ringer back on when the phone is inside my home -- I always forget to do that and miss calls) that require location information at reasonably frequent intervals... Based on ballpark estimates from other similar devices, it's probably around 70mW. This will really hurt if you keep it on all the time, fortunately, for most applications, you probably don't need to. If it works at 2s on, 30s off, as seems likely, this alone drains 1/30th of the battery per day, which isn't bad. Especially as you can probably back off a little if the phone has been stationary for several minutes. ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: GPS time synch
Ian Stirling [EMAIL PROTECTED] writes: Based on ballpark estimates from other similar devices, it's probably around 70mW. This will really hurt if you keep it on all the time, fortunately, for most applications, you probably don't need to. If it works at 2s on, 30s off, as seems likely, this alone drains 1/30th of the battery per day, which isn't bad. Especially as you can probably back off a little if the phone has been stationary for several minutes. Does GPS work well in such a mode? I seem to remember from various handheld units that it can take quite a while (minutes) to sync up to a given satellite. (For all I know, you *can* operate this way, I'm completely clueless on the subject.) -- Perry E. Metzger[EMAIL PROTECTED] ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: GPS time synch
Perry E. Metzger wrote: Ian Stirling [EMAIL PROTECTED] writes: Based on ballpark estimates from other similar devices, it's probably around 70mW. This will really hurt if you keep it on all the time, fortunately, for most applications, you probably don't need to. If it works at 2s on, 30s off, as seems likely, this alone drains 1/30th of the battery per day, which isn't bad. Especially as you can probably back off a little if the phone has been stationary for several minutes. Does GPS work well in such a mode? I seem to remember from various handheld units that it can take quite a while (minutes) to sync up to a given satellite. (For all I know, you *can* operate this way, I'm completely clueless on the subject.) Several cases. 'cold start' - this can take up to around several minutes to get an accurate position. The only time this happens is when the GPS has not downloaded an almanac in 6 weeks (either directly from the satellites (requiring being on for 13 minutes) or from the internet. Or hasn't been on for 30s every 3 or 4 hours since it last did get an almanac. If the neo has a GPS signal when it's charging, this (several minute locks) will never happen. To get lock in a couple of seconds requires a pretty good idea of your position, the time, and maybe even being able to tell the hardware chip the estimated relative speeds of the satellites. Again, if you're turning on and off the GPS every minute or so, and you're not expecting it to cope with continent sized jumps, it's not a big deal - especially if the hardware can be fed estimates, rather than trying to figure it out on its own, which it can, but it may be slower. ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: GPS time synch
GPS is much more accurate for time information, but GSM is good enough for knowing the time! Most GSM phones do sync to the network. Hopefully there are some undocumented commands for the GSM module that are unknown at this time. NTP over GPRS is a solution looking for a problem IMHO. Here is another: Detect the frequencies of a bell tower using the built-in microphone, then count the hammer strikes... voila :) Jae ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
GPS time synch
Would it be possible to keep the Neo's internal clock accurate using time stamps from GPS information? I know GPS provides that information for some output formats and that it wouldn't be the stratum 0 accuracy that you get from more expensive hardware. But it would probably be enough to stop owners from ever having to adjust their clock for second or minute drifts. My apologies if this has been covered already. ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: GPS time synch
Mark Chandler wrote: Would it be possible to keep the Neo's internal clock accurate using time stamps from GPS information? I know GPS provides that information for some output formats and that it wouldn't be the stratum 0 accuracy that you get from more expensive hardware. But it would probably be enough to stop owners from ever having to adjust their clock for second or minute drifts. I'm unsure if the hardware will provide sub-millisecond resolution, but sub-second should be very, very easy. ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: GPS time synch
Harald Welte wrote: On Mon, Feb 19, 2007 at 11:47:23PM +1100, Mark Chandler wrote: Would it be possible to keep the Neo's internal clock accurate using time stamps from GPS information? yes. That is only during GPS being powered up, of course. We probably don't want it to be powered unconditionally, since it drains quite some power. -- - Michael Lauer [EMAIL PROTECTED] http://openmoko.org/ Software for the worlds' first truly open Free Software mobile phone ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
