highaltitude.log.20080203

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[01:11] Nick change: Laurenceb -> sweet_princess
[01:12] Nick change: sweet_princess -> Laurenceb
[01:16] <Laurenceb> dont ask
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[08:16] <Hiena> Good morning!
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[10:10] <Laurenceb> hi
[10:12] <Laurenceb> edmoore: hows life?
[10:12] <edmoore> not bad thanks laurenceb
[10:12] <edmoore> fnoble and I had a bit of a marathon routing session yesterday
[10:12] <Laurenceb> I'm thinking of applying for a phd studentship with surrey satellite technology
[10:13] <edmoore> 3pm - 3am
[10:13] <edmoore> yes I saw
[10:13] <Laurenceb> lol cool
[10:13] <Laurenceb> not sure if my skills are up to it
[10:13] <Laurenceb> but IMO I've got a lot of background and basic knowledge
[10:14] <Laurenceb> I think I could work it out pretty fast
[10:14] <Laurenceb> what are you routing?
[10:15] <edmoore> the new flight computer
[10:15] <Laurenceb> for balloons?
[10:15] <edmoore> our aim of an altoids tin has made things a bit challenging
[10:15] <edmoore> yep
[10:15] <Laurenceb> cool
[10:15] <Laurenceb> I use the autorouter :P
[10:15] <edmoore> aaaaaarrrrggghhhhh
[10:15] <edmoore> a curse upon your house
[10:16] <Laurenceb> only joking, I've sometimes used it to come up with ideas
[10:16] <edmoore> it can help
[10:16] <Laurenceb> it can give you hints to new ways to route things
[10:16] <edmoore> but I like the satisfaction of a really good manual route
[10:17] <Laurenceb> http://wiki.ukhas.org.uk/projects:aerosol
[10:17] <Laurenceb> I've got some new stuff up
[10:17] <Laurenceb> it loads a kml file off the mmc card and uses it to work out the cutdown polygon
[10:18] <Laurenceb> at the moment I'm trying to get it to find the message center automatically
[10:19] <Laurenceb> also, http://wiki.ukhas.org.uk/_media/projects:radio_project.jpg a timing diagram
[10:23] <Laurenceb> this bit looks easy: http://www.developershome.com/sms/cscaCommand.asp
[10:27] <Laurenceb> edmoore: your welcome to one of the radio board, I might even have some with headers that aren't mirrored soon
[10:27] <edmoore> that's very kind of you. we have, infact, just about finished routing our own!
[10:27] <Laurenceb> lol
[10:28] <Laurenceb> are you using transmission lines?
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[10:28] <edmoore> and henry made some radio modem pics up about a year and a half ago which we have lying around somewhere
[10:28] <Laurenceb> cool
[10:28] <Laurenceb> I'm so tempted to make a mini tracking device
[10:28] <Laurenceb> gps, radio and solar panel
[10:28] <edmoore> that would be awesome :)
[10:29] <Laurenceb> I bet it could fit in a matchbox
[10:29] <Laurenceb> just power up the gps every so often to get a lock
[10:29] <Laurenceb> grr so much to do
[10:29] <Laurenceb> what do you think of the code?
[10:31] <edmoore> I haven't looked
[10:31] <Laurenceb> http://wiki.ukhas.org.uk/projects:aerosol_code
[10:33] <edmoore> I don't really have time to look at other people's code at the min
[10:33] <edmoore> plenty of my own work to be getting on with!
[10:33] <Laurenceb> lol :P
[10:34] <Laurenceb> I've almost got it to find the SMSC , but theres annoying + signs in bad places...
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[13:05] Action: Laurenceb is trying out reed solomon correction
[13:05] <Laurenceb> this is amazing stuff
[13:06] <Laurenceb> problem is I cant work out how to cross compile it to avr32
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[13:56] <jcoxon> hey edmoore
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[15:01] <Laurenceb> hi folks
[15:01] <jcoxon> hey Laurenceb
[15:01] Action: Laurenceb is writing a reed solomon python function
[15:01] <Laurenceb> I think it would actually run on the atmega168, but theres no advantage to doing it that way when I have a linux board to play with
[15:02] <Laurenceb> however, I do plan to run [255,223] reed solomon on the avr :P
[15:03] <Laurenceb> it looks like mega168 should handle it
[15:03] <Laurenceb> you can optimise it a lot with lookup tables in flash
[15:04] <Laurenceb> oh I put a new gps module up on the wiki page
[15:05] <Laurenceb> http://www.eccpage.com/rs.c
[15:06] <Laurenceb> anyway, hows life jcoxon ?
[15:16] <jcoxon> life is okay,
[15:16] <jcoxon> quite hungover :-(
[15:16] <Laurenceb> hehe
[15:16] <Laurenceb> I'm just knackered through too little sleep
[15:16] <Laurenceb> hmm how does range() work in python?
[15:17] <Laurenceb> for (i=mm+1; i<nn; i++)
[15:17] <Laurenceb> how would I do that in python
[15:25] <Laurenceb> sorted nvm, I'll bbl
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[15:37] <Laurenceb> hmm I'm thinking you dont need 8 bits, only 7 to send ascii down
[15:37] <Laurenceb> so use the 8th bit as parity, then the parity check can go into the reed solomon decoder on the ground
[15:38] <Laurenceb> as an error estimate
[15:40] <Laurenceb> that allows you to get over the (n-k)/2 limit
[15:42] <Laurenceb> but it makes hand tuning difficult, as it wont be human readable, so I'll need to hack fldigi to mask the characters before they are displayed
[15:44] <Laurenceb> bbl
[15:47] <jcoxon> dumm dee dum dum dum
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[15:54] <jcoxon> grrrrrr
[15:55] <jcoxon> damn web host
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[16:53] <Laurenceb> back
[16:54] <Laurenceb> that was refreshing, just been for a 10 mile bike ride
[16:54] <Laurenceb> its a bit nippy
[16:55] <Laurenceb> ok I've been thinking about data compression/reed solomon encoding
[16:57] <Laurenceb> so, with a [255,64] system at 434MHz 300 baud, you could get 900km range with 4.9 bytes/second effective bandwidth
[16:57] <jcoxon> Laurenceb, very oxbridge
[16:58] <Laurenceb> its fun
[16:58] <jcoxon> going cycling and thinking about data encoding
[16:58] <Laurenceb> I met some horses
[16:58] <Laurenceb> and also some chavs
[16:58] <jcoxon> such is life
[16:59] <Laurenceb> I'm thinking you could make a long duration balloon using this technique, I'll have to put some info on the wiki
[17:00] <jcoxon> hehe, i think comms are one of hte minor problems regarding a LD balloon
[17:00] <Laurenceb> I'm sure radio hams with good antenna could pick it up from 1500km or more
[17:01] <Laurenceb> you can use binary data instead of ascii, then stick an ascii callsign on the front of the packet, and use a one time pad to stop spoofing
[17:04] <Laurenceb> I'm not sure about that iron filing technique on the wiki, it might jam
[17:06] <jcoxon> iron filing?
[17:06] <Laurenceb> http://wiki.ukhas.org.uk/ideas:ballast
[17:07] <edmoore> hi jcoxon
[17:07] <Laurenceb> I'm thinking small ball bearings at the moment
[17:08] <jcoxon> Laurenceb, oh, CNES use lead ball barrings
[17:08] <Laurenceb> you'd have to find the terminal velocity, so it was safe
[17:08] <jcoxon> why not use alcohol
[17:09] <Laurenceb> its viscousity increases quite a lot
[17:09] <Laurenceb> how do they deploy the bearings, lead is nonmagnetic... ?
[17:10] <jcoxon> Laurenceb, with a valve?
[17:10] <jcoxon> i'm not sure
[17:10] <jcoxon> hey edmoore
[17:10] <edmoore> s'up?
[17:11] <Laurenceb> I want to avoid moving parts in the release mechanism
[17:14] <Laurenceb> solid powders can jam, and heated wax/plastic systems could sublime and suffer from condensation elsewhere
[17:14] <Laurenceb> its a bit tricky
[17:16] <Laurenceb> at the moment I'm thinking a vertical tube of steel ball bearings with a neodium magnet on the bottom, and a coil to counteract the field
[17:20] <Laurenceb> of course there is always LASER ABLATION !!
[17:21] <Laurenceb> but its heavy and current hungry
[17:23] <Laurenceb> ferrofluid is another possibility
[17:26] <jcoxon> god, i really can't spell
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[17:50] <Laurenceb> http://www.youtube.com/watch?v=I5Ti6PeGdNQ
[18:01] <Laurenceb> yes, ferrofluid would certianly work, but you would need the right sort, ie something with a low freezing point
[18:01] <Laurenceb> and ferrofluid datasheets are hard to come by
[18:11] <Laurenceb> basically a flexible bag a ferrofluid with a pipe out of the bottom, and an electromagnet
[18:11] <Laurenceb> ferrotech APG 510A looks good - http://www.ferrotec-europa.de/en/htmls/fluid.data.php
[18:16] <Laurenceb> pour point = -75c .. looks feasible
[18:37] <Laurenceb> http://wiki.ukhas.org.uk/code:python_reedsolomon
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[18:42] <Laurenceb> hi natrium42
[18:43] <natrium42> hi
[18:45] <Laurenceb> I'm working on reed solomon code
[19:00] <jcoxon> right, finished transfering one page of my website to a new layout
[19:00] <jcoxon> its going to take days
[19:03] <Simon-MPFH> Anyone here know anything about Gyros?
[19:03] <Simon-MPFH> Not the sort you get from the Post Office!
[19:03] <Simon-MPFH> Like the MLX90609
[19:03] <Simon-MPFH> http://www.melexis.com/prodfiles/0005359_390109060901P002.pdf
[19:03] <Laurenceb> sparkfun
[19:03] <Simon-MPFH> I just purchased their breakout board
[19:04] <Laurenceb> cool
[19:04] <Simon-MPFH> It can give rotation as an analogue or digital SPI signal
[19:04] <Laurenceb> theres my qbasic code on the wiki
[19:04] <Simon-MPFH> link?
[19:05] <Simon-MPFH> I would love to use this Gyro to keep the wings level on a model plane
[19:05] <Simon-MPFH> Easy enough to sample the roll rate and maintain an record of the roll attitude then use ailerons to correct
[19:05] <Simon-MPFH> But, my question is:
[19:05] <Laurenceb> http://wiki.ukhas.org.uk/projects:ukhas_glider_project:slave
[19:06] <Simon-MPFH> Even if you sample very fast you are only getting point samples
[19:06] <Simon-MPFH> Surely your reference will drift and make the system useless?
[19:07] <Laurenceb> use gps to correct
[19:08] <Simon-MPFH> GPS? How can that give me attitude?
[19:09] <Laurenceb> use the heading and subtract wind
[19:09] <Simon-MPFH> Like your project on the wiki - your electronics look to be waaaaay ahead of mine!
[19:09] <Simon-MPFH> Ah, crossed wires - I'm not looking for position
[19:09] <Simon-MPFH> Rather trying to keep my wings level - I see you are using a 'thermopile' to sens the horizon?
[19:10] <Laurenceb> yes
[19:10] <Simon-MPFH> Looks like your airframe is inherently stable - ie it will recover it'self from unusual attitudes
[19:11] <Laurenceb> yes
[19:15] <Simon-MPFH> I would like to 'roll to wings level' then control speed with pitch
[19:15] <Simon-MPFH> But where is level?!
[19:15] <Laurenceb> thermopiles reading equal?
[19:17] <Simon-MPFH> Indeed - I need to learn more about thermopiles - can I buy one?
[19:18] <Laurenceb> try chartland electronics they're very good
[19:33] <Laurenceb> ok http://wiki.ukhas.org.uk/code:python_reedsolomon
[19:35] <Simon-MPFH> Ah ha - http://www.revolutionmodels.co.uk/acatalog/FMS_Co_Pilot.html all done for me :-)
[19:35] <Laurenceb> lol ok
[19:35] <Laurenceb> but the opamps aren't very good
[19:35] <Laurenceb> and its analgue
[19:41] <Simon-MPFH> I see.
[19:41] <Simon-MPFH> It will do as a starting point
[19:42] <Laurenceb> yes, I'll be interested
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[19:55] <Simon-MPFH> I will be interested to see how your airframe does - I guess it will be supersonic for some time if you drop it from 100,000 feet?
[19:56] <Laurenceb> that rogallo was launched over christmas
[20:03] <Hiena> Supersonic, without engine? Impossible. At the end of the transsonic the sockwave eats the whole kinetic energy.
[20:08] <Hiena> If you makes a perfect drop, and want to go to the supersonic, you have to design a glider which could pass through the shockwave without a damage, Anyhow, it will slow down within a seconds.
[20:22] <Hiena> But, with a small , well timed, A engine it's not impossible...
[21:01] <Laurenceb> oh yes
[21:01] <Laurenceb> reed solomon is working
[21:01] <Laurenceb> :P
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[22:23] <Hiena> Sleep.
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[23:11] <Laurenceb> grr this reed solomon code is annoying me
[23:12] <Laurenceb> works with hex but not oct
[23:12] <Laurenceb> it would help if I understood the maths, but its insane stuff
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[23:18] <Laurenceb> http://www.informit.com/content/images/art_sklar7_reed-solomon/elementLinks/art_sklar7_reed-solomon.pdf
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[23:54] Nick change: MetaMorfoziS -> MeTa[AwAy]
[00:00] --- Mon Feb 4 2008