Recent content by ptosis

To add: the SNR in the track files written by Labradar is expressed in dB, not the actual absolute SNR. Using the absolute value -- (SNR/10)^10 -- gives more meaningful and precise results (I did test both when developing Labrabaco software).

Yep. Indeed, knowing QNH and alt., it is possible to calculate QFE. For the sake of completeness, there are several, more or less erroneous, pressure reduction formulae (cf. https://www.wmo.int/pages/prog/www/IMOP/meetings/SI/ET-Stand-1/Doc-10_Pressure-red.pdf), but for shooting applications...

v.0.8 is out, now with the taste of RA4, G1, and, while I was at it, G8. (The default is still G7.) Still at the same place: https://bc.geladen.ch/labrabaco/labrabaco.html All you ever wanted to know about long-range ballistics of your rimfire trainer... JBM and Strelok Pro (probably some...

Glad you liked it! Let me know how it goes when you get to it.

v.0.7 is out, now available: https://bc.geladen.ch/labrabaco/labrabaco.html The major change is noise filtering. Most people who have plotted Labradar tracks in spreadsheet software, must have seen occasional tracks of this shape: The tail of the graph -- beyond 60 ms -- is obvious noise...

Yep. Absolutely agree. In the overall balance, at mid and long range, temperature is the 3rd most important uncertainty factor, behind distance and wind. At the same time, the error of determining pressure by altitude is an order of magnitude behind these three.

just to put some more colourful pictures in the thread: median error of determining pressure by altitude but the variations in Asia are seasonal, while Arctic are not; seasonal variations (between Jan and Jul): (analysis of 10 years data from 11K+ weather stations)

I agree. And that's exactly why probabilities are important. I'd rather know my capabilities beforehand, wherever reasonably possible, rather then discover them by trial and error "with each and every single shot".

After the initial joy of owning a magnificent new Sako S20 rifle, comes the awkward "I should have taken a Tikka" moment – this is when the new owner inspects the optics mounting rails. There is a problem with the original bits of picatinny in front and behind the ejection port. Actually, three...

Just to add my CHF 0.02 to the old thread. In case you were wondering how pressure measurements affect hit probability, here's a picture: (Lapua Scenar 10 g, cal. 7.62, V0 = 850 m/s, other conditions are assumed excellent) The scenarios are: 0: ideal 2: Kestrel-style handheld barometer 7: By...

Following up on this interesting thread -- https://www.longrangehunting.com/threads/calculating-bc-with-labradar-it-works.202475/ I have put together some code to calculate G7 ballistic coefficients from Labradar tracks. The tool is available here: https://bc.geladen.ch/labrabaco/labrabaco.html...

Indeed. If I may second your recommendation not to use distance values written in the track files -- from what I see, distance is the least precise parameter, as they seem to calculate it from dt (internal clock) and velocity [calculated linear = adjusted for muzzle offset] rounded to the...

Of course, the device does have an internal clock. What I meant is that the starting "zero" point is calculated as the point in time when the blast arrives to the mic minus the time it took for the blast wave to get from the muzzle to the mic (as implied from the distance to muzzle as configured...

My understanding is that the only thing Labradar actually measures is radial velocity, that is -- velocity of the projectile to or from the device. All the rest (= figures written to track files) -- time, distance, linear velocity -- are not measured but calculated.

That is ÜBER-COOL! Thank you very, very much for sharing your data! A longread was sent in response by MP, incl. the link to the prototype calculator and the output it gives for your tracks (please let me know what you think). We just got one step closer to the Victory of Science! If anybody...