highaltitude.log.20090228

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[12:24] <hallam> fergusnoble: about?
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[12:31] <Laurenceb> hello
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[12:31] <Laurenceb> launch still on tomorrow?
[12:40] <Laurenceb> edmoore: ping
[12:41] <hallam> Laurenceb: yes, pending weather
[12:41] <Laurenceb> cool
[12:42] <Laurenceb> be seeing you tomorrow morning then :P
[12:44] <hallam> sounds good!
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[13:10] <edmoore> Laurenceb: yo
[13:10] <edmoore> Laurenceb: you have me number don't you?
[13:12] <SpeedEvil> hall: :)
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[13:17] <Laurenceb> arg hes gone :-/
[13:18] <Laurenceb> jcoxon: do you have eds number?
[13:20] <SpeedEvil> He is not a number! </prisoner>
[13:33] <Laurenceb> hmm with a dish on the ground you could talk to a balloon from 150Km with Zigbee
[13:35] <SpeedEvil> With what freq?
[13:35] <SpeedEvil> and what size?
[13:35] <Laurenceb> 2.4ghz
[13:36] <Laurenceb> 90cm dish
[13:36] <SpeedEvil> Because I got over an order of magnitude lower than that for any wifi freq
[13:37] <Laurenceb> you can get 63mw modules with -100dBm sensitivity
[13:38] <Laurenceb> 90cm dish is 26dBi
[13:38] <Laurenceb> 868MHz would actually be legal and the datarate is much less
[13:38] <Laurenceb> but I cant find any modules
[13:39] <SpeedEvil> what's the omni-omni range?
[13:40] <Laurenceb> 1.6Km
[13:41] <SpeedEvil> I get about 20* the range
[13:42] <SpeedEvil> 90cm dish is 7 wavelengths.
[13:42] <SpeedEvil> beamwidth is 1/5 radians or so.
[13:42] <SpeedEvil> Or 1/25th of a steradian
[13:42] <Laurenceb> yeah
[13:42] <SpeedEvil> this is 256 times the 12 steradians of an omni (roughly)
[13:42] <Laurenceb> maybe they are saying 1.6 with chip antennas
[13:43] <SpeedEvil> sqrt(256) is 16
[13:43] <SpeedEvil> 16*1.5=22Km or so
[13:44] <Laurenceb> yeah it might work... might not
[13:45] <Laurenceb> somewhere between 20Km and 100Km range I'd say
[13:45] <SpeedEvil> how do you get the 100km?
[13:45] <Laurenceb> but 250Kbps is mental
[13:45] <SpeedEvil> that's 1/25th of the signal
[13:45] <Laurenceb> just from the quoted -100dBm sensitivity
[13:45] <Laurenceb> for 1% packet loss
[13:46] <Laurenceb> I think the 868MHz mode looks promising
[13:46] <Laurenceb> but I cant find any modules grr
[13:47] <SpeedEvil> Fair enoguh. In that case, why don't they quote omni-omni range as not 1.6, but 1.6*5?
[13:47] <Laurenceb> bad antennas?
[13:48] <Laurenceb> maybe thats using the chip antennas
[13:48] <SpeedEvil> You have to work really hard to get that bad
[13:48] <SpeedEvil> -8dB or so on each end
[13:48] <Laurenceb> or maybe its not using high power mode
[13:49] <Laurenceb> yeah 50mw ~ 16dBm
[13:49] <Laurenceb> that would make sense
[13:49] <Laurenceb> normal mode is 1mw
[13:50] <Laurenceb> we could run IRC over zigbee :P
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[13:55] <Laurenceb> http://www.sequoia.co.uk/components/product.php?d=3&c=41&f=5&p=118&fmt=grid
[13:55] <Laurenceb> hi hallam
[13:56] <hallam> hey
[13:56] <hallam> what time were you planning to arrive tomorrow?
[13:56] <Laurenceb> 10.30am
[13:56] <hallam> at the moment the weather looks like it will be best around noon
[13:56] <hallam> ok cool
[13:56] <Laurenceb> ok
[13:56] <Laurenceb> can you emasil yours or eds number?
[14:01] <Laurenceb> I was looking at zigbee, now 868MHz is allowed, theres a zigbee mode we can use
[14:03] <hallam> oh? is there one that has a low enough bitrate to be effective?
[14:03] <hallam> (email sent)
[14:04] <Laurenceb> thanks
[14:04] <Laurenceb> well the 868 mode is 20Kbps
[14:04] <Laurenceb> the Xbee pro module should work for 100Km range or so with a 90cm dish
[14:04] <Laurenceb> but thats not very practical and on 2.4GHz
[14:05] <Laurenceb> so I'm looking for 868MHz modules atm
[14:05] <Laurenceb> Xbee pro is 250Kbps !
[14:06] <Laurenceb> 868 mode is 20KBps
[14:07] <hallam> that's still pretty fast, I'd be surprised if it could get decent range on 500mW
[14:07] <hallam> lunch/meeting time though, bbl
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[14:08] <SpeedEvil> I have some reservations about the 100Km number - it requires that they are _significantly_ under-quoting or putting _really_ bad antennas on the modules by default.
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[14:12] <SpeedEvil> Though some sums do indeed indicate that that's about the range you get with 15dB input power, 26dB antenna, 140dB path loss, 0dB antenna, -100dBm sensitivity
[14:12] <SpeedEvil> And no fade margin
[14:13] <SpeedEvil> I don't know what the atmospheric absorbtion is through lots of atmosphere.
[14:13] <SpeedEvil> Also, you need a tower.
[14:13] <Laurenceb> however.... http://www.meshnetics.com/zigbee-modules/zigbit900/
[14:15] <SpeedEvil> 1km or so high?
[14:15] <Laurenceb> eh?
[14:15] <SpeedEvil> oh - 100km
[14:15] <SpeedEvil> sorry
[14:15] <SpeedEvil> feeling horrible today.
[14:16] <Laurenceb> :-/
[14:16] <SpeedEvil> For some reason I was thinking of 300km, which means you need a moderate tower to get LOS to a balloon at modest altitudes
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[14:17] <SpeedEvil> any idea of 2.4Ghz path loss through ~20-30Km of thick air?
[14:18] <Laurenceb> nope
[14:18] <Laurenceb> but 868MHz is more sensibe
[14:18] <SpeedEvil> modulo dish gain
[14:19] <SpeedEvil> IIRC 1.8m antennas are 'relatively' cheap on ebay
[14:20] <SpeedEvil> http://cgi.ebay.co.uk/1-8M-1-85M-185cm-1-8-METER-PRIME-FOCUS-SATELLITE-DISH_W0QQitemZ310120197990QQcmdZViewItemQQptZUK_ConEle_SatCableFreeview_RL?hash=item310120197990&_trksid=p3286.c0.m14&_trkparms=72%3A1683|66%3A2|65%3A12|39%3A1|240%3A1318
[14:21] <SpeedEvil> but doubling diameter at best doubles range
[14:23] <Laurenceb> I was thinking something like http://www.amateur-radio-antenna.com/professionalantenna/antennaism868/yagidirectionalantennayism8681.php
[14:30] <Laurenceb> with that meshnetics zigbee module would give 100Km range
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[15:07] <Laurenceb> its annoying that you need a yagi
[15:07] <Laurenceb> itd be cool to have an ad hoc balloon network
[15:12] <jcoxon> hey appletizer
[15:12] <appletizer> lo jcoxon
[15:12] <jcoxon> just saw your comments on 99 :-D
[15:14] <appletizer> haha
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[16:10] <jcoxon> afternoon all
[16:10] <Laurenceb> hi jcoxon
[16:10] <Laurenceb> jcoxon: have you considered zigbee?
[16:12] <jcoxon> its crossed my mind
[16:12] <jcoxon> but the modules are pretty low power
[16:12] <SpeedEvil> Laurenceb: http://www.mike-willis.com/Tutorial/gases.htm
[16:13] <SpeedEvil> Laurenceb: say 0.007 (due to O2) per Km
[16:13] <SpeedEvil> so not that large - well under 0.7dB
[16:13] <Laurenceb> not a big problem
[16:14] <Laurenceb> less than cables ect
[16:14] <Laurenceb> need a few dB spare, hopefully 10 or more
[16:14] <SpeedEvil> yeah
[16:15] <jcoxon> Laurenceb, you thinking the 60mW on 2.4ghz?
[16:15] <SpeedEvil> http://books.google.co.uk/books?id=rx-1YAmPZycC&pg=PA142&lpg=PA142&dq=atmospheric+absorbtion+dB/Km&source=bl&ots=CKz9XVa6Ci&sig=6h-fw5QWuA_ZPO-UZfVV8tDgjuU&hl=en&ei=WmKpSbLuE-LEjAe874nXDw&sa=X&oi=book_result&resnum=8&ct=result#PPA141,M1
[16:15] <SpeedEvil> 'generally speaking, atmospheric loss is negligable under 10Ghz'
[16:15] <SpeedEvil> so that agrees
[16:15] <Laurenceb> jcoxon: no, 868MHz
[16:15] <Laurenceb> as its legit
[16:15] <Laurenceb> also the data rate is only 20kbps on 868
[16:15] <SpeedEvil> Book looks interesting
[16:16] <Laurenceb> ok
[16:16] <Laurenceb> interestingly the zigbee enables AVRs would be the trick
[16:16] <Laurenceb> *enabled
[16:17] <jcoxon> didn't know they were on 868
[16:17] <Laurenceb> theres an 868 zigbee mode, but way fewer modules/hardware
[16:17] Action: jcoxon googles and stands corrected
[16:17] <Laurenceb> http://www.meshnetics.com/zigbee-modules/zigbit900/
[16:20] <Laurenceb> that should give 100Km with a yagi
[16:20] <Laurenceb> but its only 8mw, so with a 13dBi antenna you can go to considerably higher power and its still legit
[16:21] <Laurenceb> 25mw or so woudl be fine
[16:27] <SpeedEvil> Many of the regulations are cast in terms of dBi, not dBm
[16:27] <Laurenceb> sur its erp
[16:27] <Laurenceb> so dBi+dBm
[16:28] <SpeedEvil> I mean EIRP
[16:28] <SpeedEvil> not dBi
[16:30] <Laurenceb> a sensible yagi would be 12 to 13 dBi
[16:31] <Laurenceb> so the EIRP limit is 500mw
[16:32] <Laurenceb> so you can tx 25mw
[16:32] <Laurenceb> but no 25mw 868 zigbee modules :S
[16:51] <Laurenceb> http://www.adaptivemodules.co.uk/index.cfm/fa/shopdetails/Product_ID/322/Category_ID/24
[16:51] <Laurenceb> that would work if the crystal shift wasnt too big
[16:51] <Laurenceb> ~200Km + range
[16:55] <Laurenceb> zigbee is spread spectrum so shouldnt suffer as much
[17:02] <Laurenceb> http://www.adaptivemodules.co.uk/index.cfm/fa/shopdetails/Product_ID/318/Category_ID/12 looks awsome
[17:03] <Laurenceb> its packet and should have range of 200Km on 434MHz. Theres also a calibration mode so you can retune the ground receiver to match the one in the air
[17:03] Action: SpeedEvil wants consumer-zigbee
[17:03] <SpeedEvil> It sicks that I can't go to homebase, and buy for 5-10 quid a zigbee light switch.
[17:04] <Laurenceb> then we could cause mass blackouts with a balloon
[17:04] <SpeedEvil> Hmm.
[17:04] <Laurenceb> that website has some pretty cool stuff, but I'm still tempted to go for zigbee as it should be better freq drift tolerant
[17:05] <SpeedEvil> I don't see a pressing reason why you couldn't make a 'stick on' light-switch - which is 5mm*100*100mm, and just sticks onto the wall
[17:05] <SpeedEvil> You pair it with special light-bulbs (assuming the price additional at that volume point is $0.5 or so)
[17:05] <Laurenceb> 1Khz or so of drift and that thing may have issues
[17:05] <SpeedEvil> And -50C helps lots with drift.
[17:25] <Laurenceb> that etiny thing is awsome
[17:25] <Laurenceb> 350Km range with a 12dBi yagi at 1.2Kbps
[17:25] <Laurenceb> I think thats the way to go
[17:26] <Laurenceb> theres a FLL mode as well
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[17:42] <Laurenceb> cya l8tr
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[18:08] <appletizer> aw :/
[18:08] <jcoxon> zeusbot is mean sometimes
[18:10] <appletizer> maybe it'd have to go on the next rocket launch to the moon :)
[18:11] Action: jcoxon slightly bored
[18:11] <jcoxon> oops missed the 'is'
[18:22] natrium42 (n=alexei@CPE000625d867e2-CM0014045885be.cpe.net.cable.rogers.com) joined #highaltitude.
[18:22] <SpeedEvil> wow!
[18:22] <SpeedEvil> zeusbot can summon!
[18:23] <natrium42> hi
[18:23] <SpeedEvil> hi
[18:23] <sYx66> hi
[18:23] <natrium42> hi
[18:23] <sYx66> operation duckling loop
[18:24] <natrium42> hehe
[18:29] <jcoxon> hey natrium42
[18:29] <natrium42> hello jcoxon
[18:30] <natrium42> jcoxon, let's host it at spacenear.us, it's a dedicated server
[18:31] <jcoxon> that sounds good
[18:31] <natrium42> did we decide on a name?
[18:31] <jcoxon> as SpeedEvil pointed out we don't really need a domain name as most traffic will be linked
[18:31] <jcoxon> well at least no need for a name immediatley
[18:31] <natrium42> k
[18:33] <SpeedEvil> And the stuff that's not'll be mostly caught by transatlantic halo
[18:34] <SpeedEvil> especially if we all link to the page from our personal websites mentioning that term, it should go right to the top of search results.
[18:34] <jcoxon> howabout spacenear.us/transatlantic-halo/
[18:34] <SpeedEvil> sounds sane
[18:34] <jcoxon> for the main site
[18:35] <jcoxon> spacenear.us/transatlantic-halo/wiki and spacenear.us/transatlantic-halo/tracker
[18:36] <natrium42> so it's "transatlantic" or "atlantic" ?
[18:37] <jcoxon> oh
[18:37] <jcoxon> good point
[18:37] <jcoxon> i can't remember
[18:37] <jcoxon> i think it was transatlantic
[18:37] <jcoxon> i don't really mind
[18:40] <SpeedEvil> I think I like atlantic halo better - shorter to type into a search engine - and if you know it's a balloon, the trans bit is obvious
[18:43] <natrium42> "Atlantic Halo" is good
[18:44] <jcoxon> oh go for it
[18:44] <natrium42> don't need "Halo" to represent anything
[18:44] <jcoxon> spacenear.us/atlantic-halo
[18:44] <jcoxon> yeah
[18:44] <jcoxon> i see it as a continuation of your halo launches
[18:44] <jcoxon> as we are launching it from Canada
[18:45] <natrium42> who wants access to the site?
[18:45] <natrium42> :)
[18:45] <jcoxon> i would like a wiki
[18:46] <jcoxon> so i can transfer stuff over etc
[18:46] <natrium42> ok
[18:46] <jcoxon> but i think we need a main site a well
[18:46] <natrium42> mediawiki fine?
[18:46] <jcoxon> to direct people to
[18:46] <jcoxon> i prefer dokuwiki like the ukhas wiki
[18:46] <jcoxon> but i can work with mediawiki
[18:49] <natrium42> ok, docuwiki it is
[18:49] <jcoxon> yay!
[18:50] <sYx66> yay Atlantic Halo :D
[18:51] <appletizer> don't be surprised if you suddenly get a lot of hits from Halo fans
[18:51] <appletizer> :)
[18:52] <sYx66> free hits
[18:52] <jcoxon> rjharrison said he was happy to work on the distributed listener system
[18:54] <natrium42> jcoxon & sYx66: sent you the password for spacenar.us
[18:55] <sYx66> k
[18:55] <jcoxon> amazing
[18:55] <jcoxon> natrium42, i can set up the wiki if you want
[18:56] <natrium42> that would be great
[18:56] <natrium42> i gotta run to the apple store
[18:56] <jcoxon> np
[18:56] <natrium42> my brothers laptop has problems with kbd
[18:59] <jcoxon> natrium42, what permissions should i use?
[18:59] <jcoxon> ooo don't worry i found a guide for which permissions to use with dokuwiki
[18:59] <natrium42> :)
[19:00] <natrium42> sent the password for the database user
[19:00] <natrium42> but you should create a separate user for docuwiki
[19:01] <jcoxon> its all self contained with in its dir
[19:01] <natrium42> ah, ok
[19:03] <jcoxon> crap
[19:03] <jcoxon> i've managed to lock myself out of the wiki directory
[19:03] <jcoxon> oops
[19:03] <jcoxon> can you quickly login in and delete it!
[19:06] <natrium42> you have ssh access! :P
[19:06] <jcoxon> i've got permission denied!
[19:07] <jcoxon> i by a mistake changed the dir wiki to 660
[19:07] <jcoxon> oops
[19:07] <jcoxon> i'm not normally this usesless
[19:07] <jcoxon> natrium42, don't worry i fiixed it
[19:08] <jcoxon> sorry
[19:08] <natrium42> k, cool
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[19:11] <natrium42> jcoxon, don't they have a tar.gz or something?
[19:11] <natrium42> it should have correct permissions on expanding
[19:11] <natrium42> .zip doesn't keep unix permissions
[19:11] <Hiena> ' evening!
[19:11] <natrium42> hi Hiena
[19:12] <Hiena> I want to kill the GPS chip manufactrers one by one.
[19:12] <jcoxon> lhttp://spacenear.us/wiki/doku.php
[19:13] <Hiena> They just really, really messed up the evil NMEA. Not to mention these lazy buggers set the communication speeds to the lowest baudrate...
[19:13] <natrium42> Hiena, venus gps chip has pins to configure baudrate to 115200 :P
[19:14] <Hiena> Yeah, but we works prepackaged modules. And these has only communication pins.
[19:16] <natrium42> going to solder mine today
[19:17] <natrium42> http://www.natrium42.com/gallery2/v/balloon/transatlantic/venus-gps.jpg.html
[19:17] <natrium42> needs very few external parts, so it might be a "prepackaged module" in that sense
[19:17] <Hiena> Well, i designed the connection speed-up module schematic. Now hafta etch the PCBs.
[19:18] <Hiena> Also hafta prepare the pcbs for the AOA and slip sensors.
[19:21] <Hiena> Not to mention, my injured back kills me, and being disabled makes me mad...
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[19:26] <SpeedEvil> s/ie/er/
[19:37] <Laurenceb> back
[20:00] <natrium42> back too
[20:01] <jcoxon> natrium42, Laurenceb, http://spacenear.us/wiki/doku.php?id=start
[20:02] <Laurenceb> very nice
[20:02] <natrium42> cool
[20:03] <jcoxon> i think you guys need to register to get access
[20:03] <Laurenceb> jcoxon: did you see thast module I found?
[20:03] <jcoxon> which one?
[20:04] <Laurenceb> http://www.adaptivemodules.co.uk/index.cfm/fa/shopdetails/Product_ID/318/Category_ID/12 looks awsome
[20:05] <jcoxon> look very interesting
[20:05] <Laurenceb> I get 350Km range with a 12dB yagi
[20:07] <natrium42> jcoxon, bill brown offered his HF transmitter
[20:07] <jcoxon> oh really...
[20:07] <natrium42> btw, he was supposed to launch this w/e
[20:07] <natrium42> did i miss it again?!?
[20:07] <jcoxon> no he scrubbed
[20:07] <natrium42> ah
[20:08] <jcoxon> you need to sign up to balloon_sked
[20:08] <jcoxon> http://groups.yahoo.com/group/Balloon_Sked/
[20:09] <natrium42> ok, done
[20:11] <natrium42> http://www.canada.com/news/warns+Russia+airspace+intrusion/1338063/story.html
[20:11] <natrium42> lul
[20:14] <Laurenceb> jcoxon: it looks perfect for your challenege
[20:15] <jcoxon> yes thats a good point
[20:15] <jcoxon> got for it!
[20:15] <Laurenceb> hehe
[20:15] <jcoxon> need another team to actually make it a competition
[20:17] <appletizer> migratory birds could be the competition
[20:17] <appletizer> :)
[20:18] <appletizer> speaking of that news article, i was wondering: how do stealth fighters detect each other in mid-air? it would be something if an air collision took place
[20:19] <Laurenceb> transponders
[20:19] <appletizer> well non-friendlys
[20:19] <Laurenceb> they dont
[20:19] <appletizer> a la french vs british submarines
[20:19] <Laurenceb> thats the point
[20:19] <appletizer> yeah that's what we took for granted :)
[20:20] <Laurenceb> in not combat they will have transponders so ATC can follow them
[20:20] <appletizer> i did some back-of-the-envelope calculation, it would seem that given the volume of fly-able airspace vs seawater, the chances is 1/13th that, so small but not quite so small enough :P
[20:21] <appletizer> yeah well it would defeat the purpose of stealth fighters on their mission routes if location of their whereabouts got leaked out wouldn't it?
[20:22] <appletizer> okay, stealth fighter of country X are all there there and there, let's take them out and preemptively strike :)
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[20:23] <appletizer> (maybe that explains UFO sightings, flashes of light in the night sky and loud booms :P)
[20:25] <SpeedEvil> 1W LEDs are quite inexpensive
[20:25] <SpeedEvil> As are big lenses
[20:25] <SpeedEvil> you can do a really quite impressive beam with an array of a few cree 3*3mm 1W LEDs, and a 30cm fresnel lens
[20:26] <Laurenceb> easier with lasers
[20:26] <SpeedEvil> Well - yes, and no.
[20:26] <Laurenceb> hmm aiming ok
[20:26] <SpeedEvil> several watt lasers are quite expensive
[20:27] <Laurenceb> <100mw less so
[20:27] <SpeedEvil> true
[20:28] <Laurenceb> its a bit of a pain as theres so much noise
[20:29] <SpeedEvil> Stealth fighters - for obvious reasons - have no radar.
[20:29] <SpeedEvil> at least when they're being stealthy.
[20:32] Action: jcoxon is motoring through the wiki
[20:33] <gordonjcp> someone I know who "does this sort of thing" once told me that he reckoned a Spitfire could easily down a modern jet fighter if you could catch it, but the modern aircraft would have a hell of a job getting near the Spitfire
[20:33] <gordonjcp> and he also reckoned that a Tiger Moth could down a modern fighter, again if you could catch him
[20:34] <gordonjcp> the modern aircraft wouldn't even see it because the radar and heat signature is too small
[20:34] <gordonjcp> however, a 50-cal slug is still a 50-cal slug...
[20:34] <jcoxon> yeah
[20:34] <jcoxon> they are only made of glue and wood
[20:34] <jcoxon> and a bit of fabric - that the genius behind them
[20:35] <gordonjcp> yup
[20:38] <SpeedEvil> modern aircraft would _easily_ see it
[20:38] <SpeedEvil> pilot is comparatively huge
[20:39] <SpeedEvil> Umm.
[20:39] <SpeedEvil> Also - the tiger moth has those crisscrossed wires between the wings as bracing.
[20:41] <natrium42> what about http://spatulatzar.com/fly_plane/
[20:41] <natrium42> ?
[20:42] <SpeedEvil> Hmm. 10W of LEDs (about 1W optical) in a 6 degree cone down from 30Km would be about magnitude +1
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[20:44] Action: SpeedEvil ponders congregations of astronomers, and fake supernovae.
[20:57] <Hiena> SpeedEvil, that would be the first square supernova, with heatsink fins.
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[22:06] <natrium42> jcoxon, for ballast sensor: is it possible to just use a digital scale?
[22:07] <shellevil> scales typically have a strain guage in
[22:07] <shellevil> which have problems with temp compensation, and are annoying to read
[22:08] <natrium42> hmm
[22:08] <shellevil> something simple and stupid like a linear pot and a spring might in principle work.
[22:08] <shellevil> the cap sensor seems likely to work well though
[22:13] <natrium42> true
[22:15] <Laurenceb> it worked very well with my atlas lcr
[22:15] <Laurenceb> ad7746 samples should be here monday
[22:18] <natrium42> ok, cool
[22:18] <Laurenceb> wonder if they use the same thing in car fluel tanks
[22:19] <Laurenceb> I'll reslder it in the cleanroom :P
[22:19] <Laurenceb> *resolder
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[22:25] <Laurenceb> hi there
[22:25] <Laurenceb> coming to EARS 2morrow?
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[22:29] <G8KHW> yeah - I'm Membership secretary this year
[22:29] <Laurenceb> cool
[22:29] <Laurenceb> I'll be coming along on ze train
[22:29] <Laurenceb> should be fun
[22:30] <G8KHW> so have to be ther to collect the dosh
[22:30] <Laurenceb> :P
[22:30] <Laurenceb> how much to join?
[22:30] <Laurenceb> what does membership entitle you to?
[22:32] <G8KHW> well it depends
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[22:33] <G8KHW> £18 to fly high power (H and above), £13 for model rockets £5 associate
[22:34] <edmoore> Laurenceb: what time are you arriving tomorrow?
[22:34] <Laurenceb> 10am
[22:34] <edmoore> ok
[22:34] <Laurenceb> catching earlier train now
[22:34] <Laurenceb> 7:20am :-S
[22:34] <edmoore> we're planning to leve cam at 10.30 so that works
[22:35] <Laurenceb> cool
[22:35] <edmoore> u have my number?
[22:36] <Laurenceb> yeah henry emailed it
[22:36] <edmoore> cool
[22:37] <Laurenceb> G8KHW: what do you think to this little beast? http://www.adaptivemodules.co.uk/index.cfm/fa/shopdetails/Product_ID/318/Category_ID/12
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[22:50] <G8KHW> nice and small but nothing special perfomance wise
[22:51] <Laurenceb> yeah but good enough
[22:51] <Laurenceb> 300Km + range
[22:51] <Laurenceb> with a good yagi
[22:52] <gordonjcp> interestingly enough it looks like one of the Japanese cubesats flies a pair of commercial walkie-talkies for RF duties
[22:53] <Laurenceb> theres this as well http://www.adaptivemodules.co.uk/index.cfm/fa/shopdetails/Product_ID/193/Category_ID/24
[22:53] <Laurenceb> but you'll struggle to get >50Km
[22:56] <Laurenceb> the xstream modules look good, but they dont seem to be 868MHz
[22:57] <G8KHW> The adaptive modles wont do 300Km by my calcs
[22:57] <G8KHW> +10dbm TX
[22:58] <G8KHW> -110dbm RX for 1.2Kbps
[22:58] <Laurenceb> yeah
[22:58] <Laurenceb> gives 300Km for a 12.5dBi yagi and 2.5dBi ant on the balloon
[22:59] <G8KHW> freespace path loss is 135db
[23:00] <Laurenceb> yep
[23:01] <Laurenceb> we have a 120dB+12.5+2.5 link budget
[23:01] <Laurenceb> =135
[23:01] <G8KHW> yeah if all the numbers are exactly right
[23:01] <Laurenceb> sure, but we dont really need 300Km
[23:02] <Laurenceb> 100 is ok
[23:02] <G8KHW> sure
[23:02] <Laurenceb> also thats for 1% packet loss
[23:02] <Laurenceb> and it has auto resend
[23:03] <Laurenceb> so all you will see is the effective throughput decreasing slightly
[23:03] <Laurenceb> you'll probably have data going through at considerably greater than 300Km
[23:03] <Laurenceb> not that thats going to happen - horizon
[23:05] <Laurenceb> for it to be totally legit it'd need to be 868MHz as the EIRP will be too high with 434
[23:05] <Laurenceb> (I think)
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[23:22] <Laurenceb_> hmmm http://siretta.co.uk/search_box.php?mcatid=104
[23:36] <natrium42> soldered venus chip
[23:36] <natrium42> getting the paste on the pads was the hardest part
[23:38] <Laurenceb_> awsome
[23:38] <Laurenceb_> power up?
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[23:49] <Laurenceb_> thats enought for 250kbps zigbee
[23:49] <Laurenceb_> or even PAL
[23:55] Action: Laurenceb_ contemplates hosting a site on a balloon
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[00:00] --- Sun Mar 1 2009