GPS rework: Please test and report on software fix prior to attempting any hardware fix
openmoko at mazikeen.demon.co.uk
Wed Aug 6 14:17:13 CEST 2008
On Wednesday 06 August 2008, Andy Green wrote:
> | sysfs entries! From the same location some runs have a best ttff of ~150s
> I guess it means there are "random" accesses to SD Card in background.
Perhaps, but I think I saw similar variation from the same location with the
SD card removed when the link was first discovered. It may be the GSM, the
constellation, or a neighbour using some crappy device that spews
interference too. I might try a few runs with the SD removed to get a
baseline for variation not attributable to the SD.
> | I suspect from a couple of observations that a GSM register may make ttff
> | longer, but I don't have any data to back that up - it may just have been
> | unlucky. Any ideas on how GSM status could be factored in?
> "Make a call and whistle" is what I would do. But there is pretty much
> no latitude (ha) for meddling with what GSM side is going to do.
I was thinking more of recording when the reregisters were taking place or
something. I know we don't have control over it, but I would like to rule it
in or out as a cause of interference. I wouldn't want you scratching your
head over further ways to reduce interference from the SD if GSM or some
other source was now the dominant factor.
> | I suppose I should post some results too. Note the 2 results where
> there seems
> | to have been a GPRMC result sitting in a serial buffer or something.
> I guess it won't hurt to sleep 3 after turning it off before turning it
> back on.
It already sleeps 20 after switch off as an attempt to get a properly cold
start, but I don't know if it's long enough for the ublox chip to lose its
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