Open CPN Want to smooth out SOG reading.

[ProDave]

We currently use OpenCPM version 5.1.2 on an Android tablet on our boat. It generally works very well with just one niggle. The SOG reading jumps about a lot especially when the sea is lumpy.

I have searched a lot and all I can find is you are supposed to be able to adjust the course up averaging period and although not immediately obvious it is claimed this will also affect the time that SOG is averaged for the display.

But it does not.

I set course up averaging to 20 seconds, but the SOG reading still updates every half second.

Any ideas?

Assuming the SOG is derived by change in position from the GPS, and we are using the internal GPS in the tablet, is it possible to change any Android settings to alter the GPS behaviour to solve our issue?

 

[Mark-1]

I'm not optimistic but:
If you're really lucky you could change “Location update interval”. Enable Developer Options by tapping the Build Number seven times in the About section of Settings. Look for a setting called “Location update interval”. You'll be lucky if it's there, it often isn't.

If you have no joy with that you could try this: Open Settings & go to Location and select Mode. Choose “Device only” to use GPS exclusively, rather than “High accuracy” uses additional clues. Could help reduce jitter?

 

[Laser310]

Assuming the SOG is derived by change in position from the GPS,

it is not.

You can google it.., but speed is calculated from the doppler shift in the radio wave. It is generally considered to be a more precise measurement than position.

I don't use opncpn, but isn't there a damping option?

 

[ProDave]

I don't use opncpn, but isn't there a damping option?

THAT is what I am asking. So far I have only found the north up averaging time but that does not affect the damping of the SOG display (contrary to what a search told me)

 

[Laser310]

THAT is what I am asking. So far I have only found the north up averaging time but that does not affect the damping of the SOG display (contrary to what a search told me)

the way i read your question, you were asking about android settings for the gps - presumably changing the data before it gets to the app.

i was wondering about settings in the opencpn app - specifically a damping setting

 

[Roberto]

Any ideas?

Assuming the SOG is derived by change in position from the GPS, and we are using the internal GPS in the tablet, is it possible to change any Android settings to alter the GPS behaviour to solve our issue?

There is a setting in OpenCpn where one can select ''Calculate SOG and COG from changes in position'' and can specify the amount of seconds between each calculation.
It s in Settings - Ships - Own ship, bottom lines, but it s maybe the one you already tried (?)

 

[KompetentKrew]

There's deffo a setting for this in OPenCPN.

OpenCPN devs do support herre: www.cruisersforum.com/forums/f134/

 

[ProDave]

Best I have found so far is an option to filter position/ speed via an nmea input. But I am using the GPS within the tablet and that setting does not seem to affect that. I would not know how to attach an nmea GPS to a tablet that has no I/O connections.

 

[Refueler]

Generally the GPS data for internal tablet is non user adjustable for such ... very few allow dampening data .. the averaging being fixed.

But an external GPS can usually be adjusted to average out more or dampen data ..