Hi Dylan,
am I right in thinking your system is reading only positional data, ie no doppler and no trapezoidal integration?

Te Hau said...

Hi Dylan,
>>>>>>> no trapezoidal integration?

By this do you mean, using 3 measurements for the 2sec result, like realspeed does????

Te Hau said...

It's the integration method which GPSAR is using now, although on my older version it is an option, not sure if its still optional on updates........has the effect of dropping your speeds ..depressing, that accuracy !

Yep, GPSAR trapezoidal, gives the same results as real speed, before it was slightly greater.

There was a discussion earlier, about how Mal calculated the 2 sec, as the result was always lower than manually averaging the best 2 adjacent results.
Then it was explained that the doppler 1 sec is not the average of 1 sec, it's an instantaneous reading, to get a 1 sec average you need 2 readings, to get 2sec average you need 3 readings, that's why it's less.
I'm sure Dylan has said that his results match realspeed's.

(Dylan posting via ka72"s acct)

Yes the KA72 site uses trapezoidal interpolation for speed calcs. 2sec is the most affected. 2sec peak is the average of three seconds data. This is deliberate, and a bit conservative. You can probably get better results from other software by tweaking the settings. KA72 tries to be fair by applying the same rules to everyone.

Dylan

(Dylan72 again...)
I've had a bit of a dig this morning, but I can't find anything that would lead me to believe that the GT-11 or GT-31 would use 0.1sec samples. Could you provide a reference?

Unfortunately, the most likely sources seem to be missing or very expensive to access (eg NMEA0183)