highaltitude.log.20081210

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[09:42] <edmoore> morning all
[09:53] <gordonjcp> morning
[09:57] <fergusnoble> morning
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[10:40] <jcoxon> morning all
[10:45] <edmoore> hi jcoxon
[10:45] <edmoore> just saw you got us on make - thanks!
[10:45] <edmoore> fergusnoble: just had the guy from The Sun pester again
[10:46] <jcoxon> hehe
[10:46] <jcoxon> yeah they are quite slow at updating - i submitted it last week
[10:46] <edmoore> it was on the 8th to be fair to them
[10:46] <edmoore> i just haven't been on make much in the last few days
[10:49] <jcoxon> thought they'd like it
[10:53] <jcoxon> wow i really can't be arsed to work
[10:53] <edmoore> same
[10:54] <edmoore> today is a day off
[10:54] <edmoore> backon and eggs from breakfast, i am contemplating
[10:54] <jcoxon> cambridge still going?
[10:54] <edmoore> at home
[10:54] <jcoxon> whats backon?
[10:54] <jcoxon> :-D
[10:54] <edmoore> it's bacon with the letter 'k' in it
[10:54] <jcoxon> i know
[10:54] <jcoxon> i think i'm going to reinstall my cupboard server
[10:55] <jcoxon> with ubuntu so i can get the newest sources etc
[10:55] <jcoxon> slackware is getting annoying to keep up to date
[10:56] <edmoore> i bet!
[10:56] <edmoore> in an ideal world....
[10:56] <edmoore> the lenovo x300 would run osx
[10:56] <edmoore> what are you going to do with the old ibook?
[10:56] <jcoxon> well its still got a few issues i need to iron out
[10:56] <jcoxon> the keyboard sometimes works and then goes nuts and does random keystrokes
[10:57] <edmoore> eek
[10:57] <jcoxon> actually thats the only issue
[10:57] <jcoxon> oh and the cd drive doesn't work as its got the wrong connector
[10:57] <edmoore> pfff
[10:57] <edmoore> does it have an intended task?
[10:57] <jcoxon> i'm thinking the keyboard is either a hardware issue or a software issue
[10:58] <jcoxon> both easily tested
[10:58] <jcoxon> i'll remove the keyboard and see if it still gets upset
[10:58] <jcoxon> edmoore, no intended task yet
[10:58] <jcoxon> its pretty functional though
[10:59] <jcoxon> as in its a working laptop with wifi
[10:59] <edmoore> yeah
[10:59] <edmoore> could be a distributed thingamajigga
[11:00] <edmoore> plug in a webcam and you can film the launch too
[11:00] <edmoore> anyway, time for some breakfast
[11:00] <edmoore> bbl
[11:00] <jcoxon> cya
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[13:48] <edmoore> hi Jirotka
[13:49] <jcoxon> hey edmoore
[13:49] <edmoore> yo jcoxon
[13:49] <edmoore> I think I will build a new payload today
[13:49] <jcoxon> hows the day off?
[13:49] <jcoxon> oh wow
[13:49] <edmoore> it's great :)
[13:49] <jcoxon> damn you
[13:49] <edmoore> i may turn it into a week
[13:49] <edmoore> (I jest... though actually I am out tomorrow and friday is friday)
[13:50] <jcoxon> haha
[13:50] <jcoxon> so tell me about your payload
[13:50] <jcoxon> i hope its exciting and new
[13:50] <edmoore> well... I have some rods lying around
[13:50] <edmoore> and I want it to by geometrically fun
[13:51] <jcoxon> hehe
[13:51] <edmoore> and triangles are inherently strong shapes
[13:51] <edmoore> that's about as much detail as you're getting :)
[13:51] <edmoore> because it's about as far as I've planned it
[13:52] <jcoxon> hehe
[13:52] <jcoxon> how about a repeater?
[13:52] <jcoxon> that would be cool
[13:52] <jcoxon> and with your full licence...
[13:52] <edmoore> oh this is just the geometry - it has no specific purpose
[13:52] <edmoore> though I *really* wnat to try dual deployment
[13:53] <jcoxon> oh right
[13:53] <jcoxon> so its more of a payload case
[13:53] <edmoore> I guess so yeah
[13:53] <edmoore> more of an exoskeleton
[13:54] <jcoxon> with detachable panels?
[13:54] <edmoore> maybe just paneless
[13:54] <jcoxon> oh okay
[13:54] <edmoore> will have a play anyway and see how it looks
[13:54] <jcoxon> :-)
[13:55] <jcoxon> it'll look cool
[13:56] <edmoore> there's a guy called Joel Armstrong who might be turning up here soon
[13:56] <edmoore> as a random asside
[13:56] <jcoxon> oh okay
[13:57] <edmoore> he emailed us - sounds like a good thing - big astronomy buff at Baylor University in Texas
[13:57] <edmoore> Psychology student but is a big deal in their astronomy dept
[13:57] <edmoore> sound familiar jcoxon?
[13:58] <jcoxon> hehe
[13:58] <jcoxon> a little
[13:59] <edmoore> right, better get on
[13:59] <edmoore> bbl
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[14:15] <rjharrison_> Evening all
[14:16] <rjharrison_> afternoon even
[14:16] <rjharrison_> :)
[14:16] <jcoxon> hey rjharrison_
[14:25] <edmoore> hi rjharrison_
[14:38] <rjharrison_> Hi edmoore
[14:39] <rjharrison_> Thanks for rtty help yesterday
[14:39] <edmoore> np
[14:39] <rjharrison_> Going to get the dac bit dome next to shape the pulse
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[15:23] <edmoore> Jirotka: yo
[15:34] <Jirotka> hi edmoore
[15:34] <Jirotka> sry i was gone for a while
[15:34] <edmoore> Are you the same Jirotka that google suggests is into astronomy?
[15:36] <Jirotka> i think yes
[15:36] <edmoore> cool
[15:36] <edmoore> I'd like to build a stabilised platform for a teliscope one day
[15:36] <edmoore> for a balloon mission, that is
[15:37] <Jirotka> thats awesome... although i would imagine that stabilizing it must be very difficult
[15:38] <edmoore> indeed, it's quite non trivial
[15:38] <edmoore> but not impossible
[15:38] <edmoore> Just needs careful design
[15:38] <edmoore> I profess ignorance about the telescope bit, however.
[15:38] <Jirotka> how is that?
[15:39] <edmoore> well, I don't know much about telescopes.
[15:39] <edmoore> so I'm not sure what is achievable within mass/size budgets and so on
[15:39] <edmoore> or the relative merrits of the different designs
[15:39] <Jirotka> thats true, but it mostly depends on what it is u want to look at with your telescope
[15:40] <edmoore> I was thinking the moon - we always see it there a few pixels wide on our mission shots
[15:40] <edmoore> and it's an easier target for the sort of thing I think we'd be realistically looking to achieve
[15:41] <edmoore> also needs less magnification to fit the whole moon into a photo frame, and a less-impossibley-accurate pointing system
[15:42] <Jirotka> ya that would be beautiful.. i once had the chance to get a telescope 8000 feet up on a mountain and when i looked at the moon up there it was so clear and steady that it blew me away... i cant imagine what it would be like from 100000 feet!
[15:42] <edmoore> same!
[15:43] <edmoore> that's why I'm so keen to give it a try
[15:43] <edmoore> the challenge would be to design and build the entire system to be about 4kg
[15:43] <Jirotka> that would be kinda difficult :-P
[15:44] <edmoore> what's the lightest mirror of a reasonable size - say 12cm?
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[15:46] <edmoore> hi Bluenarf
[15:46] <Bluenarf> hai
[15:48] <Jirotka> thats hard to say, im not an expert on that... but maybe it would be a good idea to use a lens telescope if it only has an apperture of 12cm
[15:49] Nick change: Bluenarf -> EI5GTB
[15:49] <edmoore> Jirotka: what is a lens telescope - mirrorless?
[15:51] <Jirotka> its a refractor, instead of using a mirror to reflect and focus the incoming light, it uses a lens to refract and focus it
[15:53] <edmoore> cool
[15:53] <edmoore> though... sounds like more glass
[15:55] <Jirotka> ya im not sure myself, a mirror would probably be better afterall... but i know from my telescope that those can get really heavy cause they need a certain thickness in order to avoid deformation
[15:55] <Jirotka> but i think for a mission such as yours, the most interesting thing to look into would be infrared astronomy
[15:55] <Jirotka> ever heard of it?
[15:55] <edmoore> heard it it, yeah
[15:55] <edmoore> not sure quite how I'd go about it though
[15:55] <edmoore> in terms of CCDs and the like
[15:56] <edmoore> though I read that some CCDs can be modded to be sensitive to IR
[15:56] <edmoore> I was thinking of an off-the-shelf SLR for this
[15:58] <Jirotka> i dont know much about the CCDs for such an undertaking, but the interesting thing about an observation platform 30km above ground, is that at that height u receive much of the infrared radiation from space, which usually is blocked to earthbound observers by waterparticles in the lower parts of the atmosphere
[15:59] <Jirotka> an infrared panorama of the milky way would be neat!
[15:59] <edmoore> ok fascinating
[16:00] <edmoore> I presume that thought to detect infrared, you need a chilled detection instrument?
[16:00] <Jirotka> probably
[16:00] <edmoore> dark is easy for visible, cool for a sensor could be quite tough - i'm not sure how the signal to noise stacks up for this as I've no intuition
[16:01] <Jirotka> me neither.. but for cold, isnt it already quite cold up there?
[16:01] <edmoore> well, -40
[16:01] <edmoore> not that cold in the grand scheme of things
[16:02] <Jirotka> i once had a teacher who did research work on infrared astronomy for the university of chicago at south pole station.. i could ask him
[16:02] <Jirotka> (if i reach him)
[16:03] <Jirotka> he should know more about that topic than i do
[16:03] <edmoore> that would be great
[16:04] <edmoore> sounds like there's lots of potential
[16:04] <edmoore> what brings you to highaltitude anyway?
[16:10] <Jirotka> well, im sort of obsessed with everything that has to do with aeronautical engineering and space exploration.. and one day i stumbled across a really nice picture of the earth from what looked like it was taken from space, but i kept reading and it said that it was taken by a high altitude balloon that was build for something like $1500
[16:11] <edmoore> so you've come to the right place :)
[16:11] <Jirotka> it looks like i have :)
[16:12] <Jirotka> and now i want to build a balloon myself
[16:13] <edmoore> awesome
[16:14] <edmoore> do you have any electronics experience?
[16:15] <Jirotka> thats where the problems kick in.. i dont really have any electronics experience, although i always wanted to learn more about it
[16:16] <Jirotka> same can be said about programming
[16:16] <edmoore> it's not a problem, you can pick it up pretty quick
[16:16] <edmoore> link 1: sparkfun.com
[16:16] <Jirotka> i really hope so!
[16:16] <edmoore> they have lots of toys that are perfect for ballooning - micrcontroller boards, gps etc
[16:17] <edmoore> and good tutorials
[16:17] <edmoore> and a great forum
[16:17] <Jirotka> cool
[16:17] <edmoore> i recommend their 'beginning embedded electronics' tutorial
[16:17] <edmoore> I also recommend googling around for 'arduino'
[16:18] <Jirotka> i ordered a book about starting with electronics, too.. i hope it will be helpful
[16:18] <edmoore> it's a board with just a basic microcontroller and other stuff on it, and it will be ideal for a balloon mission
[16:20] <Jirotka> thank you so much... what about the programming part? whenever i read through some mission designs, they involved a lot of programming
[16:21] <edmoore> inevitably they do - arduino is good because it teaches you programming aswell
[16:22] <edmoore> it's a fairly good integrated environment
[16:22] <Jirotka> good - gives me some hope :)
[16:42] <gordonjcp> you can actually program arduinos without the bloody awful "IDE" thing
[16:43] <edmoore> yes... but i think bloody aweful might be the better aproach in this case
[16:43] <gordonjcp> edmoore: well, only up to the point that its limitations and bugs prevent you getting the job done
[16:43] <edmoore> vs shipping the poor guy a 600 page 168 programmers model and a hex number pad
[16:43] <edmoore> (I exaggerate, obviously)
[16:43] <gordonjcp> like having to bodge around its inability to use header files
[16:44] <edmoore> sure, I guess actually there may be some mileage to jumping straight to win-avr or similar
[16:44] <gordonjcp> you can just use straight avr-gcc and avrdude, and use an editor that works
[16:44] <edmoore> Jirotka: what's your operating system?
[16:44] <gordonjcp> you can still use the arduino libraries, but you're not hampered by the semi-broken preprocessor and the horrible editor
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[17:53] <hallam> hello chaps
[17:53] Nick change: hallam -> hallam-food
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[18:50] <hallam> Hi Steve
[18:50] <RocketBoy> hey henry
[18:50] <jcoxon> evening RocketBoy
[18:52] <RocketBoy> anybody got anything planned - or is the weather too pants?
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[18:52] <jcoxon> the weather is pretty awful
[18:52] <jcoxon> i don't think there are any launches planned
[18:52] <jcoxon> i might be able to slip a launch in around Jan 3/4 perhaps
[18:53] <jcoxon> if the weather is good
[18:54] <edmoore> friday is good
[18:54] <edmoore> friday 9am
[18:54] <jcoxon> hehe
[18:54] <edmoore> but nowt planned as far as I know
[18:55] <jcoxon> actually i could also do 27/28
[18:55] <jcoxon> i haven't got much to fix
[18:55] <RocketBoy> what was last sunday like - it was a great day at EARS still air and clear skys
[18:55] <edmoore> RocketBoy: what is the proper name for the antenna which is 2 dipoles at 90 degrees?
[18:55] <RocketBoy> crossed dipole
[18:56] <jcoxon> RocketBoy, the weather has been pretty rubbish lately
[18:56] <jcoxon> i think last weekend wasn't great
[18:56] <edmoore> ok, thought so. google being lame
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[18:57] <RocketBoy> a crossed dipole over a groundplabe is quite a good satellite (or payload) antenna
[18:57] <RocketBoy> groundplane
[18:57] <rjharrison> Evening all
[18:58] <rjharrison> RocketBoy if possible would you mind sending me a DIP DAC I'm struggeling to find anything less than 7 quid.
[18:58] <edmoore> RocketBoy: tis why I'm looking at it
[18:58] <edmoore> gets rid of the overhead null problem
[18:58] <rjharrison> I'll cover your costs
[18:59] <RocketBoy> rharrison - i check what I have in a mo and U can choose
[19:00] <rjharrison> I was wondering if there was a capacitor solution to moving up and own the voltages. One would imagine that it would be possible to select a cap / resistor that would slow down the drop from say 2.7v to 2.5v
[19:00] <RocketBoy> edmoore: or a QFHA would be a good choice - esp at 868MHz
[19:01] <edmoore> they do look cool :)
[19:01] <rjharrison> The DAN of the antenna world
[19:01] <rjharrison> DNA even
[19:02] <RocketBoy> rharrison: yep you can get some shaping that way - a low pass filter at least - but an RC doesn't really provide the ideal shape
[19:02] <rjharrison> Ok I'll stick to the DAC
[19:03] <rjharrison> We can only really shape the voltage steps into the tx. We can't play with the RF out and filter that can we?
[19:03] <rjharrison> Not sure if the latter is even remotely possible
[19:03] <RocketBoy> I'm sure you could do the shaping with analoge components - but its probably simpler/easier to do it dans la domain digital
[19:04] <RocketBoy> you cant really pay with the RF out - otherwise you are probably voiding the licenece exempt bit
[19:04] <rjharrison> :)
[19:05] <rjharrison> OK
[19:05] <RocketBoy> the only thing I think you could do is sniff the output with a small antenna and use the
[19:05] <RocketBoy> output as a feedback on frequency
[19:05] <rjharrison> I'll stay on the input side to be fair I have exactly no idea how to manipulate the output any way
[19:05] <RocketBoy> to get frequency stability
[19:06] <rjharrison> Sounds like an area best left alone. Would you mind awfully sending a DAC if you have one spare.
[19:06] <rjharrison> I'll cover costs etc...
[19:06] <RocketBoy> probably not worth it though - simpler just to tempreture stabilize the unit
[19:07] <RocketBoy> yep - I'll check in 10mins
[19:07] <rjharrison> I have a smeking suspicion that the internal payload on icarus won't drop below 8'c
[19:07] <hallam> it's amazing what a difference the extra thermal insulation on the radio on the last few NOVA flights made
[19:07] <hallam> so much better freq stability
[19:07] <rjharrison> Ok perhaps it does then :)
[19:08] <rjharrison> THanks henry. Is that local insulation around the radiomertix
[19:09] <jcoxon> yeah we should really record the drift from each mission and compare
[19:09] <hallam> yes
[19:09] <hallam> foam and multiple layer insulation IIRC
[19:09] <hallam> i.e. layers of space blanket separated by that thin lightweight flexible foam padding stuff
[19:09] <rjharrison> We should try to standardise the information we report back from each alunch
[19:10] <rjharrison> I'll give that a go on the next launch
[19:10] <hallam> I think we should really try harder to collect accurate data on balloon fill and payload weight
[19:10] <hallam> which is something we pretty much never do
[19:11] <hallam> should use a newtonmeter to measure the excess lift just before release
[19:11] <rjharrison> Yep that would be good and record the balloon weight
[19:11] <rjharrison> Unfilled :)
[19:11] <edmoore> it would have been pretty garbage based on last flight
[19:12] <edmoore> need some good filtering
[19:12] <edmoore> maybe a generally more cunning way
[19:14] <hallam> metering gas into the balloon would be nice, but it's not something that everyone can do
[19:14] <natrium42> hi peeps
[19:14] <edmoore> sure, but high quality data is probably more important in this case
[19:14] <rjharrison> hi natrium42
[19:15] <natrium42> saw discovery canada channel interview yesterday :)
[19:15] <edmoore> that was rob, iirc
[19:15] <natrium42> yep
[19:15] <natrium42> you have the recording, right?
[19:15] <rjharrison> What does IIRC stand for
[19:15] <natrium42> or do you need it?
[19:15] <natrium42> if i recall correctly
[19:15] <edmoore> natrium42: i don't think we do, no
[19:16] <natrium42> edmoore, i could digitize it if, you want
[19:16] Action: natrium42 has it in HD
[19:16] <edmoore> i think the itvlocal ones is one of the best we had - very neat and rounded
[19:16] <edmoore> natrium42: that would be awesome!
[19:16] <natrium42> or wait, not HD sorry
[19:16] <natrium42> ok, i will try to get it to my computer from PVR later
[19:16] <hallam> cool, I'd love to see that
[19:17] <edmoore> cheers
[19:17] <natrium42> edmoore, do you have videos of the other ones?
[19:17] <edmoore> itvlocal.com
[19:17] <edmoore> then the anglia region
[19:17] <edmoore> then look back down for space teddies
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[19:18] <edmoore> The next thing to do. Really should be soon. All we need is a plan. Nothing else stopping us. So let's get on with it
[19:19] <natrium42> yeah, do something quick :)
[19:20] <hallam> fly a ZP, any ZP, with badger and no cameras, just to get experience
[19:20] <rjharrison> Hey you best be quick I have a zp ready to go soon
[19:20] <rjharrison> :)
[19:20] <rjharrison> No pressure
[19:20] <hallam> bad pun :P
[19:21] <edmoore> :)
[19:21] <edmoore> yeah, that'll be useful data
[19:21] <edmoore> can qualify the thermal model
[19:21] <edmoore> then nothing can stop us
[19:21] <rjharrison> Though I think I may need to get clearance as it is a little larger
[19:21] <edmoore> I'm not sure we do
[19:21] <edmoore> we don't need clearent to launch a zp
[19:21] <edmoore> clearence*
[19:21] <edmoore> sorry, to launch a 3kg balloon
[19:22] <edmoore> and that could take of 13m in dia
[19:22] <hallam> IIRC rjh doesn't have clearance to launch anything at the moment
[19:22] <edmoore> oooh
[19:22] <edmoore> yes
[19:22] <hallam> airspace, schmairspace
[19:22] <RocketBoy> rharrison: in my DIL A2D & D2A collection i have:
[19:22] <RocketBoy> AD7524
[19:23] <RocketBoy> AD7543
[19:23] <rjharrison> I'm not going to be very good at this but something that works between 3 and 6v would be good
[19:23] <RocketBoy> AD7580
[19:23] <rjharrison> I'll look at the datasheets
[19:23] <RocketBoy> wikewise
[19:24] <RocketBoy> I have about 1 doz each of the 1st two and 5 of the last one
[19:25] <RocketBoy> AD7524 is a 5V DAC
[19:25] <jcoxon> what temperatures do CPUs become unhappy at?
[19:25] <edmoore> 120+?
[19:25] <jcoxon> (i've had to detach the fan on my old ibook i'm fixing
[19:25] <jcoxon> )
[19:25] <edmoore> depends on their rating
[19:26] <edmoore> you do start reducing their life though if you keep em running hot
[19:26] <hallam> a fan will make a lot of difference
[19:27] <jcoxon> apparently G4s are rated above 100
[19:27] <hallam> even a little bit of forced convection really helps
[19:27] <edmoore> if i had to switch back to xp... obviously would get putty
[19:27] <edmoore> but which of the mingw/cygwin/why-did-i-leave-unix-oh-god emulators is best?
[19:27] <RocketBoy> likewise AD7543
[19:28] <jcoxon> hallam, i've removed the DVD drive so there is a lot more space in there
[19:28] <edmoore> jcoxon: keep it vertical
[19:28] <jcoxon> will reattach the fan eventually once i've fixed everything else
[19:28] <jcoxon> so edmoore i've got this large bay now in the laptop...
[19:28] <RocketBoy> AD7580 is an A2D
[19:28] <edmoore> put a something in it
[19:29] <hallam> fan, gps
[19:29] <jcoxon> usb hub + gps
[19:29] <hallam> ed, I like cygwin and xming
[19:29] <edmoore> badger board
[19:29] <jcoxon> 3g modem
[19:29] <edmoore> hallam: thanks
[19:29] <hallam> xming is a nice no-hassle free x server for windows
[19:30] <edmoore> am thinking I can't afford macs forever, and I spent 40 mins trying to get some fpga software work on 64 bit linux yesterday, to no avail
[19:30] <edmoore> so xp still has some draw
[19:30] <hallam> you can always put osx on it like Fergus did
[19:30] <RocketBoy> AD7524 is 8 bit parallel data entry
[19:30] <rjharrison> RocketBoy I'll have a look on farnel and get a 7 pound one at 2.7v I think. That way it will work with the low power lassen IQ
[19:30] <edmoore> hallam: there are differing definitions of 'on'
[19:31] <edmoore> i include sound/hibernation etc as my definiton of 'on'
[19:31] <hallam> http://videolectures.net/tict08_ventskovsky_yas/ check out the sweet nosecone mechanism at 04:17
[19:31] <edmoore> otherwise it's sort of badly welded to the side of my laptop, rather than on my laptop
[19:31] <hallam> funny, I was about to suggest that James should badly weld a fan to the side of his laptop
[19:31] <RocketBoy> and the AD7543 is 12 bit with serial interface - so I'd say that was the one for you? - less wires to solder
[19:32] <hallam> one imagines the compatibility issues will improve with time
[19:32] <jcoxon> hallam, hehe
[19:32] <jcoxon> this poor laptop, its been completely bastardised
[19:32] <jcoxon> 14" motherboard in a 12" case etc
[19:33] <edmoore> hallam: ha, that is awesome
[19:33] <edmoore> lets do it for no reason
[19:33] <edmoore> ok, sport time
[19:33] <edmoore> need to run about
[19:33] <edmoore> bbl
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[19:35] <rjharrison> Whould this DAC do the trick RocketBoy
[19:35] <rjharrison> http://uk.farnell.com/analog-devices/ad7302bnz/8bit-dac-3v-5v-dual-7302-dip20/dp/1079330
[19:35] <natrium42> rjharrison, where did you get the ZP from?
[19:37] <rjharrison> It's a solar airship from the toy shop. 11 pounds
[19:37] <rjharrison> 16 dollers
[19:37] <rjharrison> :)
[19:37] <rjharrison> Probably be crap but you never know!
[19:38] <natrium42> it will be awesome if it works :)
[19:39] <hallam> rjh, what is your flight plan for that?
[19:40] <RocketBoy> harrison yep the 7302 looks OK - I can put a couple of the AD7524 or 7543 in the post
[19:40] <hallam> payload/altitude/time aloft
[19:40] <rjharrison> fill with 1m3 attach beacon no cam and bye bye
[19:40] <hallam> launch at what time of day?
[19:40] <rjharrison> RocketBoy Would really appreciate that. I'm a bit crap at these things but i will give it a go
[19:41] <rjharrison> I like the idea of serial so I may have found another
[19:42] <hallam> if you have 5 spare pins, parallel might be easier / less complicated
[19:42] <RocketBoy> yep
[19:42] <hallam> you can just use the most sig bits and tie the others low
[19:43] <RocketBoy> yep - or hi depending on spec sheet
[19:43] <hallam> I forget which CPU you're using and programming language?
[19:44] <hallam> the serial ones need 4 wires anyway if they're SPI
[19:45] <rjharrison> Yep I think I'll go with // rather than try to send serial data
[19:45] <rjharrison> Good point hallam
[19:46] <RocketBoy> if anyone else wants some shout now - while I have them out
[19:46] <rjharrison> I was looking at http://uk.farnell.com/analog-devices/ad7303bnz/8bit-dac-7303-dip8/dp/1079413
[19:46] <hallam> it's definitely worth learning how to use serial buses at some point, but parallel is easier for now
[19:46] <rjharrison> I like simple
[19:46] <rjharrison> atmega8 with lots of spare pins ATM
[19:47] <hallam> one of the nice things about the PIC built-in "DAC" / voltage reference is that you can use two pins to set the analog voltages corresponding to the high and low ends of the scale
[19:47] <hallam> which is good for us, because we want the output to swing over a pretty narrow range for the radiometrix
[19:48] <hallam> I forget exactly, but something like 1 to 1.4V
[19:48] <rjharrison> I'm going to have to implement that somehow
[19:48] <hallam> with the one you linked, you can set the upper end of the scale, which is better than nothing, but it's good to be able to set both ends
[19:49] <hallam> that said, if you have 8 bits then it probably doesn't matter
[19:49] <rjharrison> Ok I'll look for that in a //
[19:49] <rjharrison> I couold just try without the dac and see how I get on
[19:59] <RocketBoy> rharrison: they should be in the post tomorrow
[19:59] <RocketBoy> assuming the other 1/2 remembers to do it
[20:03] <RocketBoy> BBL
[20:04] <rjharrison> Thanks
[20:57] <rjharrison> hallam, You use 7bit ascii on badger Is that to save the last bit esp as we don't need it for the telemitary
[21:06] <hallam> yeah, fergus' decision I think
[21:06] <hallam> I used 8bit on the earlier NOVA computers
[21:07] <hallam> I think 8 bit is a better idea for forward compatibility to when we finally get around to error correction
[21:07] <hallam> ASCII is a terribly wasteful way to send numbers
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[22:22] <edmoore> hi jcoxon
[22:22] <jcoxon> hey
[22:23] <edmoore> Project: The Hobble Near-Space Telescope (TM)
[22:24] <jcoxon> hehe
[22:24] <jcoxon> nice
[22:25] <Bluenarf> ha
[22:25] <edmoore> work starts tomorrow
[22:25] Nick change: Bluenarf -> EI5GTB
[22:26] <jcoxon> stablising i assume
[22:27] <edmoore> yup
[22:27] <edmoore> that'll be the tricky bit
[22:27] <jcoxon> reaction wheels?
[22:27] <edmoore> in yaw
[22:27] <EI5GTB> your actrually doing a near space telescope?
[22:27] <edmoore> yeah why not
[22:28] <edmoore> it's been up there on the list of 'cool things to do' for a while
[22:29] <EI5GTB> cool
[22:30] <jcoxon> the BLAST stuff would be a good thing to look at
[22:30] <edmoore> looked at it
[22:30] <jcoxon> :-)
[22:30] <EI5GTB> bed tiime here
[22:31] <EI5GTB> this place is to messy to maintain a calm atmosphere
[22:31] <edmoore> what time is it for you?
[22:31] <EI5GTB> 22:31
[22:32] <EI5GTB> its either bed, r sit here and get frustrated over everything.. ::P
[22:32] <edmoore> :)
[22:32] <jcoxon> hmmmm 59 degrees and the fan hasn't turned on
[22:32] <jcoxon> uhoh
[22:32] <EI5GTB> KABIOOOM
[22:32] <EI5GTB> night
[22:32] Action: EI5GTB has gone to bed (room to messy to continue operations)
[22:40] <edmoore> need to find a decent light telescope first
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[22:54] <jcoxon> bbiab
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[22:59] <hallam> ed, I can stick some pretty high magnification lenses on my star tracker
[22:59] <edmoore> I'm thinking an DSLR and a 5" reflector telescope :)
[23:00] <edmoore> though a star tracker would be ideal for pointing assistance
[23:02] <hallam> what are your plans for actuators?
[23:03] <edmoore> doodling now
[23:05] <natrium42> heh, cool
[23:05] <hallam> model aeroplane motors on sticks might do the trick
[23:05] <edmoore> on sticks?
[23:05] <edmoore> I just want a nice crisp moon shot filling the frame]
[23:06] <edmoore> maybe try andromeda - it's the same angular width as the moon
[23:06] <akawaka> http://apod.nasa.gov/apod/ap061228.html
[23:07] <edmoore> akawaka: amazing illustration - thank you
[23:07] <hallam> on sticks for more moment arm
[23:07] <hallam> nice shot
[23:08] <hallam> with props, of course
[23:08] <hallam> there should be enough air to work with
[23:08] <edmoore> oh I see
[23:08] <hallam> I wouldn't bother with reaction wheels
[23:08] <akawaka> you could consider using a webcam rather than an slr
[23:08] <edmoore> would like to be propless ideally
[23:09] <edmoore> indeed - for composite type things
[23:09] <natrium42> peroxide rockets?
[23:09] <edmoore> but slr would be nice for the quality
[23:09] <natrium42> i wonder how well reaction wheels would work
[23:10] <natrium42> and how light they could be made
[23:10] <edmoore> sounds like a job for mr. experiment man
[23:10] <natrium42> laurence?
[23:11] <edmoore> no, a fictional character
[23:12] <natrium42> exactly
[23:14] <edmoore> this is mr experiment man (I apologise in advance) http://www.king-mag.com/online/wp-content/uploads/2008/11/itdept.jpg
[23:14] <natrium42> lol XD
[23:15] <hallam> oh sweet jesus
[23:16] <hallam> trouble with reaction wheels is you have to desaturate them, though maybe you could use air damping for that
[23:16] <hallam> they're a lot of hassle though
[23:16] <hallam> I shared a lab with someone using them over the summer
[23:16] <hallam> little propellor-based thrusters would be much easier IMO
[23:16] <edmoore> did he smell?
[23:16] <natrium42> hallam, how well would they handle vibration?
[23:16] <hallam> she was better looking than that guy
[23:17] <edmoore> i think I would only want to use them for a few secs at a time
[23:17] <hallam> then what? if you turn them off you get the opposite torque
[23:17] <edmoore> some big clunking orthogonal gyros would be nice
[23:17] <edmoore> just to damp out crap
[23:17] <edmoore> hallam: yes - but I don't care at that point
[23:18] <edmoore> it can do it's own spinny thing
[23:18] <hallam> ok, so then you wait 20 minutes for the air to damp the rotation before you take the next exposure?
[23:18] <edmoore> i stick massive paddles out the side to damp it faster :)
[23:20] <hallam> well, your call
[23:20] <edmoore> will do some research
[23:20] <hallam> but I think a few small propellors would be lighter and more effective
[23:20] <natrium42> hallam, you're right
[23:20] <natrium42> it's hard to controll a spinnig mass quickly enough
[23:20] <natrium42> *spinning
[23:21] <hallam> the rig they were using in my lab had enormous reaction wheels and they didn't have much control authority
[23:22] <natrium42> perhaps propellers or compressed air engines would be better
[23:22] <edmoore> I'm not going near compressed air
[23:22] <edmoore> -40 tends to arse things up
[23:23] <natrium42> there are peroxide rocket engines :P
[23:23] <edmoore> :)
[23:23] <hallam> you have free reaction mass all around you, may as well use it
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[23:44] <natrium42> hallam, that dude (?) edmoore linked to does
[23:44] <edmoore> ?
[23:44] <natrium42> <edmoore> this is mr experiment man (I apologise in advance) http://www.king-mag.com/online/wp-content/uploads/2008/11/itdept.jpg
[23:44] <edmoore> reaction mass
[23:44] <natrium42> mass is mass.
[23:44] <edmoore> i can imagine his reaction mass is undamped though
[23:45] <natrium42> XD
[23:45] <edmoore> spends a few minutes oscillating after every reach for a slice of pizza
[23:45] <natrium42> haha
[23:48] <edmoore> you only need about 1/125th of a sec to get the moon, I seem to remember
[23:48] <edmoore> this is def possible
[23:48] <edmoore> sure, andromeda would take very much longer
[23:50] <jcoxon> ooo what have i missed
[23:51] <edmoore> Hobble
[23:51] <edmoore> and how the andromeda galaxy is about 3 times the angular width of the moon
[23:51] <edmoore> so could be another good target for the hobble near-space telescope
[23:54] <jcoxon> how about webcam astronomy
[23:55] <jcoxon> might make life easier
[23:55] <jcoxon> especially due to the low temperatures
[23:55] <edmoore> like slr photography but lower resolution
[23:56] <jcoxon> its pretty impressive what gets done with water cooled CCD with hundreds of images that are then postprocessed
[23:56] <edmoore> more impressive with hundreds of slr pics :p
[23:58] <jcoxon> hehe fair enough
[00:00] --- Thu Dec 11 2008