Hello everybody
Having recently installed a hobby-boards lightning detector I’ve been tracking various storms using nexstorm and blitzortung websites.
I have noticed that different nexstorm websites sometimes show a storm in a totally different location and blitzortung generally shows far more strikes than nexstorm. Is there a reason for this?
Many Thanks
Nikki
If properly calibrated, a Boltek detector can get an accurate bearing to the lightning strike, but a single unit can only make an educated estimate of the distance. The distance estimates can be adjusted to get a better value by comparing the readings to known good data and adjusting some calibration factors, but there is no good way of accurately determining the range with only one instrument. Then again, if you just slap one up and do not spend some time adjusting the calibration settings, it is only going to be in the same country as the ballpark. To get accurate lightning data, you need to get direction readings form two instruments, spaced a distance apart, and triangulate to get the position.
Steve
If you have GRlevel3 it should be a simple matter to range your detector, for those in the US or southern Canada. I’m not sure if the free feed plots lightning but I know Allison House does.
Rick
Thanks for the replies
Think i understand whats going on now, its just that i though all nexstorm / boltek sites would agree where the storm actually was/is. It appears that some don’t.
I have now range tested my detector and it would seem that i can get 75miles. This is a little too much for me so think I’m going to reduce the high of my “antenna”
I also get quite a few false positives which always occur between 8:30am and 10:00am so hopefully reducing the size of the antenna will stop them.
Nikki
I’ll be really interested in how this goes Nikki. I have one of these but found it impossible to remove the 100’s of false positives I was getting so I gave up. I wanted to get mine working just to know there was a storm in the vicinity but found it impossible to get working reliably.
I notice that none of the UK based Bolteks give anything like a realistic plot of a storm, I have been watching one out of the window and looked on more than one Boltek site and none was within 50 miles of the actual storm. I thought I’d like a Boltek but the cost is prohibitive and on looking at UK sites I’m not convinced they are value for money considering the inaccuracy.
Stuart
Hi Stewart
I’ve now reduced the height by over half, I’ll test for a day or two and then post back here to let you know what I’ve found.
I too am surprised how inaccurate some of the boltek sites seem to be, but perhaps that’s just a local site config / calibration problem.
At the moment I’m following this thread: Excellent work for lightning detector with a great deal of interest.
Nikki
Did you reduce the length of the antenna, or its height above ground? The former would be the best way to reduce sensitivity.
Nikki - I’m just in the progress of helping to set up a ‘Lightning Radar’ network here in NZ, how have you found the correlation between nexstorm and blitzortung websites for storms?
Cheers
Colin.
Hi Colin
Its very early days but based on collected data for yesterday (a very active thundery day) i have found blitzortung to be far more accurate 
blitzortung showed very clearly a storm nearby (storm physically observed) but nexstorm sites were a bit patchy. Some were agreeing with my observations others were way off the mark.
But more generally (older observations) I find blitzortung better than nexstorm.
More research is required…
Nikki
It’s hardly fair to compare blitzortung, which is a site that works by triangulating data from multiple stations, with untriangulated, independent boltek sites.
Hiya
I suppose i reduced the length of my antenna - to clarify here’s a little outline of my setup.
My lightning detector PCB is installed inside a waterproof “junction box” below my solar radiation shield making it about 1 metre above the grass. Before modification my antenna used to run up my anemometer pole to a height of about 30 metres but i found that i was getting false positives between about 7:30 and 10:00 daily. Tonight i reduced the height of the antenna making it about 5 metres long. This makes it about 6 metres about the surface.
Hope that makes sense…
I’ll report back with results of the modifications in a few days…
Nikki
Perhaps…
But I’m only just learning about lightning detection…
I thought that all boltek sites were triangulated, is this assumption incorrect?
Nikki
No, if you just buy a boltek and create a website then that’s not triangulated with any other station. The boltek can resolve the direction pretty well because it has a three antennas (all in one little plastic box) and the direction can be computed from the three signals, but the distance is only an estimate based on the strength of the signal. With a lot of time spent on calibration that estimate can be quite good, but I have the impression that few users really do that.
Blitzortung is a site that takes data from multiple boltek users and computes strike position by triangulation (signal from the same strike received by multiple boltek stations).
OK I understand whats going on now - i just hope i haven’t offended any boltek owners :oops:
This is after all my first expedition into the science of lightning detection.
Thanks again
Nikki
My mistake, I understod that Blitzortung was a site that correlated only the Lightning Radar project stations, which is why I asked for the comparison. I see now that it in fact uses data from both Boltek, LR and other lightning detection systems.
Cheers
Colin
you have boltecs that send their nexstorm data to a one place repository, and then the strikes that match up the best are plotted
StrilkeStar (Sphere Technologies) does that
Unfortunately strikestar in europe is fragmented into several different web sites, but blitzortung has a nice big map covering it all.
Hi Stuart
I’ve now been running my detector with a much shorter antenna and so far I’ve reduced my false positives by about 90% I’m still detecting storms perhaps about 40 miles away (which I’m quite happy with)
I still get a batch between 8:30 and 10:30. Does anybody know if its possible to omit this time range from the WD graph?
Nikki
not possible
8O
The hobby boards card comes with a 24’’ (60 cm) antenna and they estimate a 50 mile range… if you had a 29m antenna, I’m not surprised you got false readings… these false readings were probably someone lighting a cigarette with a peizo lighter 3 miles away!!