GPS/SD issue hardware fix vs. software fix

Alastair Johnson alastair at
Mon Oct 20 13:17:09 CEST 2008

Risto H. Kurppa wrote:
> Hi!
> Some months ago we had this GPS time to first fix issue that was
> handled with a software fix. However the new Freerunners ship with the
> hardware fix (you can see a small capacitor in the connectors of SD
> card).
> Is someone able to give us some test results hos much better the hw
> fix is? TTFF with two FR's where one has and the other one doesn't
> have the HW fix, using the same software.

I don't think the hardware fix is any better. With the updated kernel 
and no hardware fix I see TTFF in line with chipset specifications, 
often around 40s, whether I have the SD in or not. The kernel update 
allows the 'fix' to be controlled in some detail, and I posted a script 
that repeatedly cycles through the available settings recording TTFF. 
This shows both the variation in TTFF with the different settings, and 
the variation in TTFF over multiple attempts at different times in the 
same location.

Having said that I don't think there have been any definitive tests 
posted. I'll have a look to see if I have a test unit with the capacitor 
installed, but I can't promise anything.

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