highaltitude.log.20081021

[00:06] <rjharrison> The zeusbot took some hassle tonight
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[00:13] <rjharrison> nights guy
[00:13] <rjharrison> nights guys even
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[09:07] <rjharrison> Moring edmoore
[09:07] <edmoore> hello thar
[09:08] <rjharrison> Got GPS conversion to decimal working last night
[09:08] <rjharrison> What I would have given to have had that last weekend
[09:10] <edmoore> it's not too trixy
[09:10] <edmoore> and now you can do all sorts of delicious fun
[09:10] <edmoore> http://wiki.ukhas.org.uk/ideas:landing_spot_prediction
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[09:14] <rjharrison> Be interesting to get that to work on the atmega8
[09:15] <rjharrison> I didn't realise that the gps coods could not go striaght into google. Bit of a major oversight really.
[09:15] <edmoore> shouldn't be too bad actually
[09:15] <edmoore> the code isn't that big
[09:15] <rjharrison> No fp on the atmega8
[09:15] <edmoore> i think google maps can deal with them but earth can't
[09:16] <rjharrison> Humm I couldn't get google maps to work. Perhaps I didn't put the correct units on the digits
[09:17] <rjharrison> Hey ho at least i got it right
[09:17] <rjharrison> Well found it I mean
[09:17] <edmoore> you don't need fp units to do fp
[09:17] <rjharrison> No I saw tht from the conversion last night
[09:17] <edmoore> you can emulate it with software. takes a bit more code space and a lot more cycles
[09:17] <rjharrison> pad with 0
[09:18] <rjharrison> and int dev and then move back down
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[09:25] <rjharrison> edmoore I may have an easier system
[09:25] <edmoore> oh?
[09:26] <rjharrison> Not as scientific. But distance to limit line / altitude and drop on threshhold
[09:28] <rjharrison> limit line = uk boundary lines
[09:29] <rjharrison> Making some prudent assumptions about descent rate
[09:29] <edmoore> sure
[09:29] <edmoore> we have done simpler things like that too
[09:29] <edmoore> radius limit and so on
[09:29] <rjharrison> The theory is the same but simple math by removing some calcs
[09:30] <rjharrison> If I write some suedo code i may pass it by you for some expert opinion
[09:30] <edmoore> i'm not sure I'm best qualified but will happily look over it
[09:30] <edmoore> you could check out the line crossing algorithm if you want
[09:31] <edmoore> that's a simple algorithm that sees if you're inside a polygon or not
[09:34] <edmoore> right, lectures. bbl
[09:34] <rjharrison> Basically I want to jettison the balloon if dist_to_bound/alt < threshold
[09:34] <rjharrison> Chers
[09:34] <rjharrison> ttfn
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[14:29] <rjharrison> Hi Edmmore
[14:29] <rjharrison> opps )
[14:29] <rjharrison> no conv. on HA since you left for lectures this morning
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[14:41] <edmoore> rjharrison: yo
[14:41] <edmoore> such is life
[14:41] <edmoore> I am about to hit the library anyway
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[15:05] <SpeedEvil> http://www.bunny-comic.com/?id=1246
[15:06] <jcoxon> hehe
[15:07] <gordonjcp> heh
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[16:27] <jcoxon> rjharrison, did you use a UV lense on your camera?
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[16:43] <rjharrison> Yes jcoxon
[16:44] <rjharrison> Did you get that bit about using a guide for cutting. Made all the difference.
[16:46] <rjharrison> The uv lense was a cheep optical glass window to seal the box from the environment. Placed on foam, drew circle cutout circle leaving a ride about 1/2 way through the sheet for it to rest against and then low melt glued into place
[16:47] <rjharrison> Effectively sealing the box from the elements save a very thin breathing hole underneath where the antenna cable protruded from the flight box. There was about a 2mm gap around the wire to allow for pressure changes
[16:48] <rjharrison> uv lense 52mm from jessops 15quid can prob get them cheaper. It was convenient 4 me
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[16:56] <jcoxon> rjharrison, oh thanks
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[17:11] <Laurenceb> hello
[17:16] <Laurenceb> edmoore: that question about Z transforms, I think it can be done with fourier transforms provided certain criteria are met
[17:17] <edmoore> like you don't want any transient response information?
[17:17] <Laurenceb> yeah
[17:17] <edmoore> well a FT is just a laplace/z-transform in the limit
[17:18] <Laurenceb> it needs to be stable and causal :P
[17:18] <edmoore> take away the real component of the exponential index and hey presto
[17:18] <edmoore> *why* that makes a different, I'm not entirely sure
[17:18] <Laurenceb> wihich per a parafoil and a heavyside step function control input is not the case
[17:18] <edmoore> I have often tried to work out why making your index complex rather than imaginary should suddenly vomit out the transient
[17:18] <Laurenceb> *for
[17:19] <Laurenceb> well... the maths works
[17:19] <edmoore> exactly
[17:19] <Laurenceb> so, I'm thinking can you stick in a simple trial controlloop to make it solvable?
[17:19] <edmoore> but I do want an intuition for why, one day
[17:20] <edmoore> that would probably make sense, though I think it's very much within the bounds of conventional discrete control theory - i.e. z-transforms
[17:20] <Laurenceb> yeah
[17:21] <Laurenceb> it appears you could only solve a parafoil with fft if its got some feedback to stop it spiralling in response to a heavyside test input function
[17:22] <edmoore> can you just call it a test function like the rest of the world :p
[17:22] <edmoore> step function*
[17:22] <Laurenceb> the spiralling is not stable in the control theory sense at least
[17:23] <edmoore> well...
[17:23] <edmoore> it's desperately non linear
[17:23] <edmoore> so it's not really in control theory
[17:24] <edmoore> I would just make happy fairly assumptions about equilibrium and assume deviations from it are small enough to be absorbed by your gain and phase margins
[17:24] <edmoore> fairy*
[17:26] <Laurenceb> yeah
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[17:26] <Laurenceb> I have some test data recorded at 5Hz for proportional control where I released a rogallo off target by ~30 degrees
[17:26] <natrium42> hello *
[17:27] <Laurenceb> hi
[17:27] <Laurenceb> http://wiki.ukhas.org.uk/_media/projects:ukhas_glider_project:rogallonowind.png
[17:27] <Laurenceb> and http://wiki.ukhas.org.uk/_media/projects:ukhas_glider_project:fft.png
[17:27] <Laurenceb> is the fft
[17:27] <natrium42> ooh
[17:28] <edmoore> from my lecture this morning on some fairly unpleasant integral:
[17:28] <edmoore> "It could be anything, it could be 'christmas tree' ... so lets call it tau."
[17:28] <natrium42> what manoeuvre is that?
[17:28] <Laurenceb> natrium42: its from last year
[17:28] <Laurenceb> well, I think its equivalent to a step function input
[17:29] <Laurenceb> in which case I could try some funcky control theory on it
[17:29] <Laurenceb> I also tuned the PID loop by hand, so I can see if I got the same results
[17:30] <SpeedEvil> http://www.youtube.com/watch?v=7obLT4s2-HA&NR=1
[17:30] <SpeedEvil> tea with chopsticks!
[17:30] <SpeedEvil> surface tension ++
[17:32] <edmoore> actually these notes are unintelligible
[17:32] <edmoore> "Sigma is the charge on the surface of the surface."
[17:32] <Laurenceb> lol
[17:33] <edmoore> followed by some notes on the calculation - "What'll kill you is the minus sign at the end of the day. It'll slaughter you like a pea."
[17:33] <Laurenceb> speedevil: wtf
[17:34] <Laurenceb> high voltages?
[17:34] <SpeedEvil> high voltages?
[17:34] <Laurenceb> oh... its on the iss
[17:34] <Laurenceb> I thought he was using static on the droplet surface to control them
[17:35] <jcoxon> wow these conversations are really weird= control theory, chirstmas trees, tea and chopsticks
[17:37] <edmoore> "If you look at *anything* side on and it looks like a rod THEN IT'S A ROD"
[17:37] <edmoore> some advice from dynamics lecturer for this examples paper
[17:37] <Laurenceb> I see
[17:38] <natrium42> edmoore, so tell the prof that he looks like a rod from the side
[17:38] <natrium42> the conclusion follows
[17:38] <edmoore> he has big curly hair so it wouldn't work
[17:38] <natrium42> bah
[17:39] <edmoore> my favourite quote from some notes about the engineering course, which just about sums up cambridge - "Any evidence of coping will be penalised"
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[17:39] <natrium42> lol
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[17:40] <Laurenceb> I'm basically trying to look like I'm doing some work atm
[17:40] <Laurenceb> havent got a clue what I'm doing
[17:40] <natrium42> Laurenceb, just try to look annoyed
[17:40] <edmoore> I have come from the library to my laptop, at 5.00, to use matlab to try and solve a question on bit error rates
[17:40] <edmoore> I have yet to open up matlab
[17:41] <edmoore> this is dire
[17:41] <Laurenceb> I dont get this use of matlab for everything
[17:41] <natrium42> i just had a midterm exam
[17:41] <edmoore> it's the most important bit of software ever made
[17:41] <natrium42> german, so it was damn easy...
[17:41] <Laurenceb> you can use c and this stuff called paper
[17:42] <edmoore> Laurenceb: or you can use matlab
[17:42] <Laurenceb> can matlab do symbolic integration?
[17:42] <edmoore> yes, though i would use something else for that
[17:42] <edmoore> what it can do is eye digrams
[17:42] <Laurenceb> qed
[17:43] <Laurenceb> maple+c+paper
[17:43] <edmoore> when you have to 2^5 bit combinations, doing it by hand becomes tedious
[17:43] <Laurenceb> is all we ever use in physics
[17:43] <Laurenceb> none of this matlab nonsense
[17:44] <edmoore> I suppose matlab does analysis
[17:44] <edmoore> so isn't so useful to physicists
[17:44] <Laurenceb> lol
[17:45] <Laurenceb> I was reading a paper on control loops for galileo reception, and there code was in matlab
[17:45] <edmoore> all of industry uses matlab
[17:45] <Laurenceb> I just dont get it
[17:45] <edmoore> simulink
[17:46] <edmoore> now you get it
[17:46] <Laurenceb> it would be just as easy to use c
[17:46] <Laurenceb> no
[17:46] <edmoore> unfortunately it would be actually very much harder to use c
[17:46] <Laurenceb> as most of the techniques the used werent supported in matlab
[17:47] <Laurenceb> so they were fassing about with stuff that could as easily have been written in c
[17:47] <edmoore> b = a + c'
[17:47] <Laurenceb> sure they had some fancy graphics, but thats what gnuplot is for
[17:47] <edmoore> where each of them are 17 x 17 square matrices
[17:47] <Laurenceb> edmoore: a library
[17:48] <edmoore> so you're basically writing a very large collection of C libraries
[17:48] <edmoore> to do numerical analysis and manipulation
[17:48] <edmoore> and at the end you will end up with..... matlab
[17:48] <Laurenceb> no you c&p
[17:49] <edmoore> but when you want to quickly crunch some data, you don't want to write huge chunks of tangentially related code
[17:49] <Laurenceb> but with matlab you still have to write it in c to actually use it on your system
[17:49] <edmoore> then spend hours debugging it
[17:49] <Laurenceb> sure
[17:49] <Laurenceb> its ok for just testing things
[17:49] <Laurenceb> but you can also do that with maple
[17:50] <edmoore> and octave
[17:50] <edmoore> and numpy
[17:50] <edmoore> I don't see what your point is
[17:51] <Laurenceb> that people are excessive with their use of matlab
[17:51] <edmoore> intepreted, very high level languages are much better than f**king around with c every time you want to do some engineering/physics
[17:52] <Laurenceb> the physics community wouldnt agree :P
[17:52] <Laurenceb> *everything* uses c/c++
[17:52] <edmoore> ok, just engineering then
[17:54] <Laurenceb> can matloab export eps graphics?
[17:55] <edmoore> of course
[17:55] <Laurenceb> ok, one positive
[17:55] <Laurenceb> but loads of papers with matlab graphics seem to use png or even jpeg
[17:56] <Laurenceb> which is pretty retarded
[17:56] <edmoore> i always just dump the eps into latex direct
[17:56] <edmoore> nice and easy
[17:56] <Laurenceb> yeah
[17:57] <Laurenceb> its cool being able to zoom into a figure in a pdf
[17:57] <edmoore> right, hall time
[17:57] <edmoore> bbl
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[17:57] <Laurenceb> cya
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[18:33] <rjharrison_> Opps looks like left myself logged on at work
[18:33] <rjharrison_> :-]
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[18:36] <rjharrison_> EI5GTB How is you AVR stuff going?
[18:39] <Hiena> Muahahahaha... There will be some really heavy lifting.... I've got a material for the balloon. It will be almost 6.5 meter diameter and nifty 135 qubic meter capacity. At 35 degree delta T it will provide netto 9 kg lift.
[18:41] <Ei5GTB_> rjharrison, its not..
[18:41] <Ei5GTB_> i gave up when i wasnt good at it
[18:42] <Hiena> And the guys from the university said, if the things would be fly they will gives me 200 qubic meter nitrogen for free. That means, it'll fly even without the sunpower!
[18:43] <gordonjcp> nitrogen is an ineffective lifting gas
[18:44] <Ei5GTB_> so is neon
[18:44] <Ei5GTB_> but you dont hear me complaining
[18:45] <Hiena> Why? It's cheap, and has 0,02 kg/qubic meter lift compaired to the same temperature air. At this scale it's same as the estimated weight of the ballon.
[18:48] <Hiena> One 20 sq.meter balloon material costs 1.5 EUR and weights, 0.430 kg. The total surface od the balloon is 127.3 squaremeter, which is with the wires and the ductapes is around 4 -4.5kg.
[18:50] <Hiena> If we fill it with nitrogen it has enough capacity to lift a 200g drops without external heat surce.
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[20:05] <rjharrison_> EI5GTB aww you shouldn't give up
[20:05] <rjharrison_> I had a real battle at first but it worked out in the end
[20:06] <EI5GTB> yea, when it came to interrupts, i just packed it in!
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[20:29] <jcoxon> evening all
[20:48] <jcoxon> hey G8KHW
[20:49] <G8KHW> lo jcoxon
[20:50] <jcoxon> was just saying hi :-)
[20:51] <G8KHW> yeah hi lo
[20:51] <G8KHW> ;-)
[20:54] <jcoxon> pretty much finished my payload case - thet joy of hotwire cutters
[20:54] <rjharrison_> Excellent
[20:55] <jcoxon> need some more hot glue gun sticks
[20:55] <rjharrison_> Lets have a pic at your hot wire cutter
[20:55] <jcoxon> oh no - its very scrappy
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[21:02] <rjharrison_> aww
[21:03] <jcoxon> hehe
[21:11] <jcoxon> G8KHW, in the rtty string what is the APU16N bit?
[21:17] <G8KHW> its used by APRS i think as the destination for broadcast position packets
[21:17] <jcoxon> oh okay
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[21:20] <G8KHW> here is an example packet
[21:20] <G8KHW> IZ3LCJ>APU16N,WIDE2*,qAo,IR3CO-5:=4548.14N\01217.48E-IZ3LCJ op.MAURO QRV 145.650 R2TV-145.450
[21:21] <G8KHW> thats from IZ3LCJ
[21:21] <jcoxon> okay
[21:22] <SpeedEvil> Auxillary Power Unit 16 of course!
[21:22] Action: SpeedEvil thinks 16 APUs might be overkill.
[21:24] <jcoxon> you never know
[21:30] <jcoxon> hmmm i wonder when the UTARC trans-atlantic season start
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[21:31] <rjharrison_> Is that when they send balloons accross to us from the US
[21:31] <jcoxon> yeah
[21:31] <jcoxon> very exciting 3 days of tracking
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[21:32] <rjharrison_> Hey to they broadcast the frequencies
[21:32] <jcoxon> its on 10metres i think
[21:32] <rjharrison_> Blimy that's some antenna
[21:36] <gordonjcp> jcoxon: I remember hearing bips and beeps from weather balloons on the, ahem, 11m band in the late 70s/early 80s
[21:37] <jcoxon> oh cool
[21:38] <jcoxon> yeah the Spirit of Knoxville is very cool
[21:38] <jcoxon> they have an IRC channel for htelaunch
[21:38] <jcoxon> lots of people - especially the US balloon guys go on it
[21:38] <jcoxon> its a lot of fun
[21:39] <rjharrison_> What is the channel
[21:39] <jcoxon> ummm i can't remember off hand
[21:39] <jcoxon> its dead right now
[21:42] <jcoxon> oasis.liveharmony.org #SNOX
[21:42] <rjharrison_> Thanks JC I'm going to add that and watch it
[21:42] <jcoxon> used the zeusbot archive search
[21:43] <jcoxon> haha its just natrium and I
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[22:25] <rjharrison_> A bit of photoshop http://www.robertharrison.org/files/icarus/IMG_0435%20-%20Curves.JPG
[22:25] <rjharrison_> Any thoughts?
[22:27] <gordonjcp> rjharrison_: nice
[22:27] <gordonjcp> what was shopped?
[22:28] <gordonjcp> incidentally did you spot the contrail?
[22:28] <rjharrison_> Can you miss it
[22:28] <gordonjcp> not really
[22:28] <rjharrison_> The one on the water :)
[22:28] <rjharrison_> Just adjusted the colors the orginal was a bit washed out
[22:29] <rjharrison_> That contrial is cool though it makes you realise how high you are
[22:33] <gordonjcp> ye
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[23:49] <edmoore> all
[23:49] <edmoore> hello
[23:51] <rjharrison_> hi ed
[23:51] <rjharrison_> Off to bed i'm afrid
[23:51] <rjharrison_> nights all
[23:57] <rjharrison_> BTW edmoore: If you get a sec have a look at http://www.robertharrison.org/files/icarus/IMG_0435%20-%20Curves.JPG
[23:57] <edmoore> rjharrison_: nice
[23:58] <edmoore> playing with the levels?
[23:58] <rjharrison_> Bit of colour correction to make it look more real
[23:58] <edmoore> :)
[23:58] <rjharrison_> check out the contrail on the water
[23:59] <edmoore> it does look pretty awesome, I must say
[00:00] --- Wed Oct 22 2008