[Loadstone] Direction fix mode

Shawn Kirkpatrick shawn at odyssey.cm.nu
Mon Dec 3 00:19:05 GMT 2007


After giving this some more thought I think what we're talking about is 
reinventing static navigation mode. The problem is like this:
assume a walking speed of 4 kilometers per hour, that translates to just 
over 1 meter per second. Unfortunately that value is well within the drift 
for most receivers. Trying to compensate for that would mean knocking out 
speeds below the drift range and that would be pretty much all walking 
speeds. Waiting until a certain distance had gone passed might work but 
would result in intermitant speed readings. You'd only get a reading when 
the distance had been met and then it would drop back to 0 until the next 
calculation. If we assume that on a good day the receiver's drift radius is 
8 meters then that means you'd only get a speed reading every 8 seconds, the 
rest of the time it would be 0. That's not a good situation at all.
I think we'll have to see the results of software heading and speed 
calculations before we can think of how to fix the drift problem. There 
probably just isn't a good way around this, if the receiver's sending bad 
position data then there's no accurate way of correcting it.

On Sun, 2 Dec 2007, Jurgen wrote:

>> The biggest
>> problem I can see with this would be a slow response
>> at low speeds.
>
> Thats the point! A slow responce that is useful is much beter
> then a useles fast one.
>
> And the ones who want to have the fast useles function, can set
> the value to zerro - and gon!
>
> There is a possibility to find a better way, but it is combined
> with collecting positions in a circle buffer with variable size.
> And I think, it is much to complicated for this problem
>
> And for Your argument, that GPSReceivers would have this ...
>
> for the first, GPS for walkers still is not the main market. And
> there is a big problem for the producers of receivers. Thay have
> to be compatible to NMEA standard to fid then neets of the market
> and to feed LS ;-). So they can only support, what NMEA can
> transport. there is no NMEA data set, that can communicate, how
> the direction is calculated. It's  the same problem as the one,
> that we don't get information about battery status. deo You
> think, this is because  it is so complicated to calculate battery
> status?
>
> J.
>
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