Blitzortung.org Forum

Hello,
Dealing with raw data I wondered how accurately the whole system (especially concerning Europe) is working.
When downloading raw data the coordinates are given with an accuracy of five or six decimal places. Calculating worst case scenario (a stroke being detected on the equator) the maximum deviation would be calculated as following:
5 decimal places: +- 55,5 m
6 decimal places: +- 5,5 cm
(The stroke was detected in a circle with +- x metres round the given position.)

I do not think the network is able to calculate positions of strokes with this accuracy, can it?
Secondly I wondered about the deviation parameter "mds" descibed as giving the maximum deviation in nanoseconds. Am I right this value refers to the stroke´s timestamp given at the beginning of each line? But in what way does this affect the position of the stroke?
(Could it be the radius of the circle is calculated by multiplying the deviation "mds" with c = 299 792 458 m/s?)

best regards
PothThom

and thanks for your time...

A radio wave spreads with the speed of light. The timestamps are measured with an accuracy of 1 µs. In 1 µs a radio wave covers a distance of about 300 m.

cu Robo

The accuracy depends on a lot of factors:

- a strike has also a horizontal expansion, we reduce this to a 2D-coordinate
- trigger accuracy on the individual stations, some strikes have spread/noisy signals which are difficult to trigger
- irregularities of the radio propagation (for example echoes or sky-wave bounces)
- algorithm on the server 

As far as I understand is mds calculated from the offset between the used stations from the calculated position.

If you look at the signal of false positive strikes, you'll see that the majority of used stations have false triggers, which "accidentally" make sense to be a strike at a certain location, if it fits the tolerance. So i wouldn't nail accuracy down to the mds.

Hello,
thank you.
So I have to calculate with a steady value.
But in what range does the accuracy fluctuate?
(I know this may be an internal value but is a deviation of +-10 km
justifiable concerning Europe?)

Best regards,
PothThom

In exceptional cases the error can be more than 100km, but that may occur on less than 1 out of 100'000 strikes. (depending on some factors)

In most cases mds would be correct, but not always, thats what I tried to say

Hello,
sorry then I misunderstood you.
Thank you very much for your help.

Best regards,
PothThom