[Nottingham] Reading realtime Android GPS into a PC

[david at gbenet.com]

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On 17/06/12 20:08, Martin wrote:
> On 17/06/12 19:12, david at gbenet.com wrote:
>> On 17/06/12 17:52, Martin wrote:
>>> Folks,
> 
>>> Anyone know of an Android/Linux utility pairing to read position
>>> and time data from a smartphone GPS in realtime and across USB
>>> (or bluetooth) onto such as a netbook/PC?
> 
> 
>> Perhaps Viking" can do it - but there are lots of GPS interfaces
>> out there though somearea brain ache - if you can transfer your
>> data then Viking will show it - with the option of downloading maps
>> and charts.
> 
> I'm not so worried about the maps and charts... I'm just interested in
> relative displacement and time, and integrating (averaging) multiple
> samples to try to gain greater relative precision.
> 
> I can get a list of samples easy enough from a logger and then run
> through the GPX file offline. What would be neater is to hook up to a
> netbook or RasPi for some realtime cleverness :-)
> 
> I may even look up using GPS as an ntp source again... (However, that
> bit is rather low priority as a fun aside.)
> 
> 
> Cheers,
> Martin
> 
> 
> _______________________________________________
> Nottingham mailing list
> Nottingham at mailman.lug.org.uk
> https://mailman.lug.org.uk/mailman/listinfo/nottingham
> 
Hello Marin,

As a sea captain one always wants to know one's position - which relative to the size of
one's vessel. "Relative position" in UK waters and on dry land - is always a matter of some
15 to 20 metres "out." There is no such thing as pin point accuracy in the  UK - whereas in
the rest of the world you get anything less than a metre. What this means is in the UK you
cannot rely on your GPS to steer you into a harbour at night - in the rest of the world you can.

have no idea why satellites are "out" by 15 to 20 metres in the UK. I'd trust driving down a
state highway in the US in thick fog - but I'd not trust doing the same in the UK!! So if
you wanted accurate time - I'd suggest you take up a  position at least 2,000 nautical miles
out side UK waters!!! :)

I've also experimented with three GPS units - none of which gave the same positioning data
and all had an accuracy of 15 to 20 metres. All these GPS units where built in the USA and
can take advantage of DGPS. Your relative "displacement" or your relative position is
dependent on your size - the bigger you are the error falls into insignificance. If you are
an 600ft long vessel a 60ft error in UK waters makes no difference. If you are a 45 ft boat
it does.

A GPS is only useful in coastal waters - or route planing in a truck or car. Traditionally
coastal navigation was done by 3-point triangulation - your position was always relative to
the size of the "cocked-hat" where the lines crossed - the closer the lines the more
accurate your position. You can test how accurate your GPS is by doing 3-point triangulation.

Have fun!!

David

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