Warranty after fix for GTA02 GPS rework for SD card interference issue

Andy Green andy at openmoko.com
Fri Aug 1 01:39:35 CEST 2008

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Somebody in the thread at some point said:

| I did some testing today to add some more data points (or fuel on the
| fire, depending on your point of view :-)

Let's say you did nice work there enabling us to converge on an
understanding of the issue :-)

| What I did was run three test, one with the SD card removed, one with
| the SD card installed but idle and one with the SD card being used
| heavily. For each test, I ran simultaneous tests on two other GPS
| receivers to give a reference point.
| The short version is that SD card activity really messes up the GPS, the
| long version can be found here (complete with pretty plots and tables
| and everything :-) :
| http://www.millions.ca/~stacy/neoFreeRunner/gpstale.html

About the 600sec thing, you can get the GPS chip to report 4 times a
second instead of once a second, maybe that can be to do with it.  But
it is strange, noticing the heavy filtering on our results I wonder if a
lot of those samples coming so quickly were actually synthetic.

For the last result, it seems to show only 2 / 2500 results from GPS are
within 20 Million meters of the location.  It's hard to square that with
the other decent results that have been reported for tracking, including
ones pulling maps from SD Card, although I guess you are spamming the
card as hard as you can for this test.

What actually happened when gpsd died?  With that and the extreme nature
of the last result I wonder if something else goes on.

One last thing, the voltage scaling and clock rate reduction patches
aren't in the kernel you used, they should be around in tomorrow's
packages: if you have 600 sec to spare it would be interesting to see if
they made any change :-)

- -Andy
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