nescivi wrote: very rarely we did indeed have packet losses across the laser link, but since they were so few and far between (even in bad weather), i don't have reliable data. one possible weakness in the whole scheme is that the UDP redundancy methods of both jacktrip and netjack will send redundant packets right next to each other, so that if you have a burst failure (which is common), you are screwed. for me, the morale is: lasers can be made reliable enough if you can tolerate the occasional single or short burst packet loss (loss rates of about 0.0001%), the general internet cannot, unless you get end-to-end QoS, but you can sneak past that if you have lots more bandwidth than you are going to need. but nothing in the world short of http streaming will protect your ass against crappy border gateways and switches that barf on udp stream traffic. as to bird losses, the class 3 lasers operated at 8mW, so the chance of a bird being vaporised is, ahem, slim. the main issue with respect to laser safety was eye damage. the minimum safe distance to look directly into the laser was about 50m. but since IR lasers do not trigger a lid-closing reflex (you only see a dim red shimmer), this minimum safe distance is determined for a duration of 100s of continuously staring into the lens (for lasers in the visible range, this duration is below 1s, iirc). so you would actually have to hover in front of the laser for well over a minute before your retina takes serious damage. therefore, we can safely rule out eye damage to birds as well, unless they are very skilled flyers, very bored and very very stupid. as to stupid people: on the spire, the laser was mounted so that accidentally looking into it was impossible. it was ascertained that no members of the public would ever come near the device without a guide who would inform them of the dangers. the khm site was off-limits to the public, and on both sides, barriers and warning signs discouraged direct access to the laser devices. no photons were harmed during the creation of this event.

Fons Adriaensen wrote: wow. somebody finally did it? i know there have been at least two attempts before, and both were cancelled as the expenses were skyrocketing :) the tricky part of the heli quartet is that not only do you need 4 bi-directional wireless audio links (the quality of which is pretty secondary, given the available s/n inside a helicopter - i guess you could do it with standard uhf audio gear and pimped antennae), but you also need 4 very high quality video links for the musicians to be shown on screens in the auditorium. and i would imagine a helicopter cockpit to be a quite emr-unfriendly environment, and the available power to be rather noisy... even greater than the engineering challenge will be the challenge of getting anybody to pay for that bs^H^Hthe realisation of such a visionary piece of art. which seems to have succeeded :) <flamebait>while i do have a soft spot for the old geezer from sirius, i think the money would have been better spent on a whole bunch of other works less heavy on artistic hubris and a bit better equipped in the taste department.</flamebait> jörn

On Sunday 18 January 2009 14:22:02 Jörn Nettingsmeier wrote: The first was at the opening of the HANGAR-7 in Salzburg. There's a documentary about it: http://www.bfmi.at/stockhausen.htm I only found one image of the show in high quality: http://www.redbull-photofiles.com/Photofiles/PhotofilesModule/ShowSubsectio… (picture 220803H703 ) I understand why they do it on time, but why repeat it? Flo -- Machines can do the work, so people have time to think. public key 6C002249 x-hkp://wwwkeys.eu.pgp.net