[Ovmsdev] How to get a quick and reliable GPS fix

[Christopher Cook]

Hi Arthur,
I don't know much about this myself but I do know my TomTom satnav (not 
GPRS enabled) requires a regular QuickGPSFix update downloaded to keep 
it up to date with expected satellites. SatNav's without that update 
have to rely on historical information about the satellites instead.

Regards,
Christopher Cook

On 05/11/2014 00:42, Arthur Hebert wrote:
> Hi All,
>
> Does anyone know the details of how, most reliably and most quickly, 
> to get a location fix from the GPS module after it has been powered up 
> and after it has come out of sleep mode?
>
> I have written my own code using the OVMS hardware. To save power, it 
> turns off the GPS power (AT+CGPSPWR=0) and puts the module to sleep 
> (AT+CSCLK=2) while the vehicle is parked (i.e. no CAN bus activity). 
> Once there is CAN activity again, it comes out of sleep mode 
> (AT+CSCLK=0) and turns on the GPS (AT+CGSPPWR=1). Immediately after 
> turning on the GPS power, I also issue one of the GPS reset commands 
> (AT+CGPSRS=0 or AT+CGPSRST=1).
>
> The module documentation if vague about when to use the 0 reset or the 
> 1 reset.
>
> I know that the GPS module itself isn't made to function while the 
> module is asleep even though the commands may not give an error.
>
> I've read that it takes up to 15 minutes to get a fix on most GPS 
> devices. In practice, sometimes I get a fix within a minute every time 
> I start up, and other times I don't get a fix even after hours of 
> trying with either reset option.
>
> Any information will be greatly appreciated.
>
> Thanks,
> Arthur
>
>
> _______________________________________________
> OvmsDev mailing list
> OvmsDev at lists.teslaclub.hk
> http://lists.teslaclub.hk/mailman/listinfo/ovmsdev

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openvehicles.com/pipermail/ovmsdev/attachments/20141105/2725fa2f/attachment.htm>