highaltitude.log.20080104

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[10:43] <weather> Hi all
[10:43] Nick change: weather -> Laurenceb
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[10:57] <Laurenceb> hey edmoore
[10:58] <edmoore> hi laurenceb
[10:59] <Laurenceb> I'm thinking of getting one of the 5Hz gps units off sparkfun :D
[10:59] <Laurenceb> for the micro rogallo
[11:00] <Laurenceb> it looks possible to make it weigh<60 grams
[11:02] <Laurenceb> I'm thinking of making the board double as a datalogger
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[12:01] <jatkins> hi all
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[14:25] <neontube> afternoon all
[14:25] <Laurenceb> hey neotube
[14:26] <edmoore> hi neontube
[14:27] <edmoore> laurenceb, I've been trying to squeeze a complete flight computer into an altoids tin
[14:29] <Laurenceb> cool :D
[14:29] <Laurenceb> what processor?
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[14:31] <edmoore_> the pcb is shaping up, but it's kind of cramped. One entire side is just shielded metal boxes - a telit gsm module, a lassen IQ GPS, and a radiometrix radio. between them they take up all the surface area of the pcb, so the mcu and all that will have to go on the other side of the pcb
[14:31] <Laurenceb> ok
[14:31] <edmoore_> thankfully there's still plenty of room for routing on the gps/radio/gsm module side of the pcb
[14:31] <Laurenceb> so its got a single processor?
[14:31] <edmoore_> it'll run off the cortex, yeah
[14:32] <Laurenceb> will you be maving microstrip lines on the pcb?
[14:32] <Laurenceb> they take up a bit of space
[14:32] <edmoore_> though actually, telit now sell something pretty interesting looking - a telit module with integrated arm9 entirely for customer applications - amazing
[14:32] <Laurenceb> cool
[14:32] <edmoore_> microstrip?
[14:33] <Laurenceb> for rf transmission
[14:33] <Laurenceb> for your rf lines
[14:33] <edmoore_> ok
[14:33] <edmoore_> well there don't actually need to be any
[14:33] <edmoore_> which is the nice thing
[14:33] <Laurenceb> oh RS sell sarantel geohelix antenna
[14:34] <edmoore_> the telit module has a built in connector
[14:34] <edmoore_> the lassen iq has the antenna mount on the module
[14:34] <Laurenceb> thats ok, they are a pain to design
[14:34] <Laurenceb> I designed one to connect to the radiometrix module for my radio
[14:34] <edmoore_> yes, this is one of the advantages of these modules. as they're all shilded too, it should hopefully make emi issues less of an issue
[14:34] <edmoore_> well i will need one for the radiometrix
[14:35] <edmoore_> but that's not the end of the world
[14:35] <Laurenceb> yes, I'll email you my design
[14:35] <edmoore_> although.... I quite like the idea of having that external to the altoids box
[14:35] <Laurenceb> but its on my usb stick and it wont mount on kubuntu grrrr
[14:35] <edmoore_> built it onto the groundplane and antenna unit, with just the cable with signal and power
[14:35] <Laurenceb> yes
[14:35] <edmoore_> as in - pulse shaped voltages
[14:35] <Laurenceb> I'm trying to find super high voltager supplies
[14:36] <edmoore_> i don't really want it within the emi case... that might eb unfounded. something to look in to
[14:36] <Laurenceb> my CCFL moulse is outputting 4KV ac
[14:36] <Laurenceb> module*
[14:36] <edmoore_> is inductive boosting not up to it? I'm pretty ignorant on HV stuff so forgive me
[14:36] <edmoore_> you could build effectively a solid state coil
[14:37] <Laurenceb> no, I'm using capacitor multipliers, but some of ther caps are now too low voltage
[14:37] <edmoore_> tsla coil*
[14:37] <edmoore_> tesla*
[14:37] <Laurenceb> edmoore: thats exactly how it works
[14:37] <Laurenceb> except its not tesla as thats inefficient
[14:37] <Laurenceb> it draws 70mA at 5v :D
[14:37] <edmoore_> wow
[14:38] <edmoore_> that's very reasonable indeed
[14:38] <edmoore_> does is spark at all?
[14:39] <edmoore_> you *could* do a wide band telemetry transmitter
[14:39] <edmoore_> if you could module telemetry onto your HV panels
[14:39] <edmoore_> modulate*
[14:39] <edmoore_> that might be taking the iss slightly, but pretty cool :)
[14:39] <Laurenceb> rofl
[14:39] <Laurenceb> nah no sparks :D
[14:40] <Laurenceb> I just got b*llocked by the mphys projects coordinator, for complete disregard for health and safety
[14:40] <Laurenceb> well not really
[14:41] <Laurenceb> she was basically freaked out to discover I was working on a 4KV supply without a safety assesment
[14:42] <Laurenceb> I've got some HEPA filters, so they will go between the HV precipitator and the vacuum pump, then theres a mems pressure sensor
[14:43] <Laurenceb> that will be read by the AVR, which will control the pump through a pid loop using pwm and a mosfet
[14:44] <edmoore_> awesome
[14:44] <Laurenceb> I also got an aerosol generator, you can program in the particle size and density and away you go :D
[14:44] <edmoore_> so the pump is just a normal brushed DC?
[14:44] <Laurenceb> yes, with a wankle rotor on the end
[14:44] <edmoore_> teeheehee
[14:45] <Laurenceb> I've got so much cool kit :P
[14:45] <edmoore_> Take a photo!
[14:45] <Laurenceb> I will soon promise
[14:45] <edmoore_> You know for once my bench now looks like a proper elecronics bench. I finally feel I can make anything
[14:45] <Laurenceb> :D
[14:46] <edmoore_> I've got a scope, a dual PSU, and a temp controlled soldering iron.
[14:46] <edmoore_> it's all such a pleasure to use, after years of bodging
[14:46] <Laurenceb> I need my own scope
[14:46] <edmoore_> it's the best single thing I have
[14:46] <edmoore_> for example, I once had to generate a saw tooth wave from a pic
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[14:47] <Laurenceb> I use an old ATX supply as my lab supply
[14:47] <edmoore_> couldn't see if it was doing it with a multimeter, so i wired up an led to see
[14:47] <Laurenceb> yes, I know all about these tricks
[14:47] <edmoore_> and sure enough it was flashing on and off, so the pic was obviously generating the wave
[14:47] <Laurenceb> for audio frequency, you can use earphones a lot
[14:47] <Laurenceb> thats how I debugged the avr radio code
[14:48] <edmoore_> but then when i built the rest of the system, it wasn't really working properly. wasn't until I got a scope on it that i saw there was a ground loop somewhere which was really smothering the signal and smearing the peaks
[14:48] <Laurenceb> yes, ground loops are always strangely behaved
[14:48] <Laurenceb> I could get an avr programmer to work for ages once
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[14:49] <Laurenceb> discovered the mains cables going to the lab supply and pc were forming a ground loop
[14:49] <jcoxon> hey troublemakers
[14:49] <Laurenceb> hey jcoxon
[14:49] <neontube> trouble makers ? us ? never !
[14:50] <Laurenceb> right I'd beeter get back to searching for HV caps, need to get this order sent off
[14:50] <jcoxon> neontube, still got one of thats weather sat recivers lying around?
[14:50] <edmoore_> jcoxon, I must tell you about the altoids thing. sorry the rest for repeating myself
[14:51] <edmoore_> jcoxon: I've been working on a pcb to fit in an altoids case
[14:51] <edmoore_> you've got roughly 50mm x 80mm
[14:51] <edmoore_> the telit module happily takes up half of it almost perfectly
[14:52] <Laurenceb> grrr why doesnt rs have a parametric product search
[14:52] <neontube> yer playing with it now
[14:52] <neontube> well attempting to set up the antenna in the lost anyway
[14:52] <edmoore_> the lassen iq takes up about 2/3 of the remaining half
[14:52] <edmoore_> i might be able to squeeze a radiometrix into the remaining space, but I'd quite like to be terminal blocks and stuff there, and keep the noisy radio external
[14:53] <edmoore_> anyway, so hardware like that takes up all of one side of the pcb, leaving me with the other side for the MCU and all the rest
[14:53] <edmoore_> It'll be a squeeze, but I reckon it's do-able
[14:53] <jcoxon> okay cost?
[14:53] <edmoore_> and would look sooo cute
[14:53] <edmoore_> yes... well the expensive bits are the telit
[14:54] <edmoore_> the gps is £35, telit is about £65
[14:54] <edmoore_> and probably about £50 for the rest
[14:54] <edmoore_> inc external radiometrix
[14:54] <edmoore_> and pcb production
[14:54] <edmoore_> so not all that cheap. but we could make the telit optional if we wanted to sell it
[14:55] <edmoore_> and put an fbus interface in for nokia stuff
[14:55] <jcoxon> such as shame that teh telit gps module uses sirfIII
[14:55] <edmoore_> yep
[14:55] <edmoore_> well it's a nice backup
[14:55] <edmoore_> if the main gps fails we could turn on the telit one
[14:55] <jcoxon> but it just adds to the cost i guess
[14:55] <edmoore_> but i'd want to keep it off most of the time for power reasons
[14:56] <edmoore_> yes, tho we could get one of the non gps modules
[14:56] <edmoore_> but they're only slightly cheaper, so you may aswell get the gps one
[14:56] <edmoore_> i'm not sure we'll have the height to fit in a battery too. but if we do, that's be rocking
[14:56] <edmoore_> right, i need to go to the dry cleaners
[14:56] <edmoore_> i'll be back in half an hour to discuss further if u want
[14:57] <jcoxon> should be still around, am getting bored in the library
[14:58] <edmoore_> ok bbl
[14:58] <neontube> jcoxon: u interested in one of these receivers then ?
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[14:59] <jcoxon> they sound quite cool, and i saw the software you can use with your sound card to decode them
[15:00] <neontube> yer thats what i'm going to try and do
[15:00] <neontube> but i'm not sure if the frequencies its set to are still in use (presets)
[15:01] <jcoxon> well if you have a spare unit that might work
[15:01] <jcoxon> (you mentioned you had a few?)
[15:01] <neontube> yup
[15:01] <jcoxon> what is the model?
[15:01] <neontube> they were designed for the bbc micro orinaly
[15:01] <jcoxon> :-)
[15:02] <neontube> i'll take some piccies in a bit
[15:02] <jcoxon> astrid receivers?
[15:04] <neontube> griffin weather satellite reciver
[15:04] <neontube> NOAA and Meteosat
[15:04] <neontube> Noaa is the polar orbiting one
[15:04] <neontube> meteosa is the geostationary one
[15:04] <jcoxon> cool, i googled bbc micro and sat
[15:05] <jcoxon> and it came up with astrid but the sat they use doesn't seem to still work
[15:05] <neontube> u need a 1.5m dish for the for the metosat one, but it was too big to keep so binned it a year or 2 ago
[15:06] <jcoxon> don't have much space :-)
[15:07] <neontube> the antenna needed isn't much smaller
[15:07] <jcoxon> but yeah if it isn't too much hassle would be fun to play with
[15:07] <neontube> its got 3 of the 10 presets populated
[15:07] <neontube> 137.300 - 137.500 and 137.620
[15:08] <neontube> and they just push into little sockets
[15:09] <jcoxon> what are you now using as an antenna?
[15:09] <neontube> proper one that came with it
[15:09] <neontube> i'll find a pic of it
[15:10] <neontube> http://www.time-step.com/products_apt.htm
[15:10] <neontube> scroll down
[15:10] <neontube> its the first sort (simple cross design)\
[15:11] <neontube> 136.50 for NOAA 12 and 15 and 137.62MHz for NOAA 14
[15:11] <neontube> still looks like 2 of the xtals are usable the
[15:12] <jcoxon> hmmmm i've got nowhere to put an antenna, apart from my small balcony
[15:12] <jcoxon> which is south facing
[15:13] <neontube> run it down to a post in the ground outside for testing:P
[15:15] <neontube> humm... says it won't work through buildings, but i have seen one site where the guy had it in his loft
[15:15] <jcoxon> there is no reason why i couldn't mount an antenna off my balcony
[15:15] <jcoxon> would get 50% of the sky
[15:16] <neontube> well u would get part of the image
[15:16] <neontube> think it transmits line at a time in a continuos stream
[15:17] <jcoxon> sounds very coo,l
[15:18] <jcoxon> cool*
[15:19] <jcoxon> apparently for the meteosa you need south facing
[15:20] <neontube> yer
[15:20] <neontube> and the big dish
[15:20] <neontube> its got a fairly low horizon too
[15:21] <neontube> right... anttenna is in the loft
[15:21] <neontube> all i need is a 12v power supply and i'm sorted
[15:22] <neontube> but that will have to wait a while :( got to finished tidying something up before the wife wakes up
[15:22] <neontube> see if u can find out when the next pass is
[15:22] <neontube> bbl
[15:25] <jcoxon> for which sat?
[15:25] <neontube> noaa 12 or 15
[15:25] <jcoxon> okay
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[15:33] <jatkins> hi all
[15:34] <edmoore_> hi jcoxon
[15:34] <jcoxon> neontube: noaa 15 next passes 04:07pm
[15:34] <jcoxon> where i am, it rises at 4.07 and sets at 4.23
[15:34] <jcoxon> noaa 12 won't pass over
[15:36] <jatkins> jcoxon: nearly finished a camera shutter trigger with an arduino
[15:36] <jcoxon> hows that going?
[15:36] <jatkins> good, thanks
[15:36] <edmoore_> I've just read the discussion - we had one of those in our old design technology lab
[15:36] <edmoore_> ran continuously for years
[15:36] <edmoore_> with the wether
[15:36] <edmoore_> weather*
[15:36] <jcoxon> jatkins: have you wired it all up then?
[15:37] <jatkins> not quite
[15:37] <edmoore_> jatkins - what have you got to do left?
[15:37] <jcoxon> i put a little guide on the wiki
[15:37] <jatkins> oh cool
[15:37] <jatkins> I just need to solder it to the arduino
[15:37] <jatkins> I've got it to manually take a picture by crossing over both wires on the solder pads though
[15:37] <edmoore_> jatkins: awesome - you've very nearly there then
[15:37] <jcoxon> doesn't your ardunio have sockets?
[15:38] <jatkins> it's a diecimila
[15:38] <jatkins> not sure
[15:38] <jatkins> I was just going to solder to the pads on the back of the PCB
[15:38] <neontube> noaa12 dead now then ?
[15:38] <jcoxon> on the top though doesn't it have sockets you could push the wires into?
[15:39] <jcoxon> as its best not to make things too permanent
[15:39] <jatkins> oh, yeah
[15:39] <jatkins> ok
[15:39] <jatkins> thanks
[15:39] <jatkins> I'll have a go now
[15:39] <jcoxon> http://science.nasa.gov/temp/NOAA12Loc.html
[15:39] <jatkins> bbl
[15:41] <jcoxon> it has been decommisioned
[15:43] <edmoore_> jcoxon, have you any experience with usb drivers?
[15:43] <jcoxon> some
[15:44] <jcoxon> whats up?
[15:45] <edmoore_> It's one of those situations where I'm committing something to a pcb without necessarily being sure how do to the firmware
[15:45] <edmoore_> :)
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[15:46] <edmoore_> I know it's possible so I guess I may aswell go for it
[15:46] <edmoore_> there's a dedicated hardware usb port on the arm
[15:47] <jcoxon> is it slave or host usb?
[15:50] <edmoore_> i think slave
[15:50] <neontube> sat reciver powered up and tuned to 137.500 which should be noaa 15
[15:51] <neontube> just hiss and the odd stray tone on it at the mo
[15:51] <edmoore_> i'll only want to *either* have it as a mass storage device, where it has telem, and you can enter a config file, *or* both mass storage and a more interactive mode for dynamic config over the usb connection in terminal
[15:51] <jcoxon> neontube: whats your long lat?
[15:52] <neontube> dunno off top of head
[15:52] <neontube> s45 9jf if u have a post code converter
[15:52] <jcoxon> yup
[15:52] <jcoxon> on my phone
[15:52] <neontube> thats if that post code is in it
[15:53] <neontube> not that old a house
[15:53] <jcoxon> yup got it
[15:54] <neontube> its over south africa at the momment
[15:54] <edmoore_> jcoxon: show-off
[15:54] <edmoore_> :p
[15:54] <jcoxon> just cause i have a groovy phone
[15:55] <neontube> what phone u got ?
[15:55] <jcoxon> nokia navigator
[15:55] <neontube> pah
[15:56] <jcoxon> yeah its the same, 4:07:59pm rise
[15:56] <jcoxon> hehe
[15:57] <neontube> ooo i can here some extra tones now
[15:57] <neontube> very faint and very noisey
[15:57] <neontube> its just about to hit te equator
[15:58] <neontube> i need to find a realy old 5pin din connector now
[15:58] <neontube> so i can hook it up to the mic input on my laptop
[15:58] <neontube> currently using the internal monitor speaker on te reciver
[15:59] <jcoxon> old school
[15:59] <neontube> lol thats where te box came from :-P
[15:59] <neontube> my old school
[15:59] <neontube> and the others came from the electronic repair service the county concil used to run
[16:00] <neontube> when they shut down they gave all the kit away to anyone that could be bothered to fetch it
[16:00] <neontube> so i got a nice digital storage scope with digital readout tracer points,
[16:00] <neontube> and a nice 0-30v bench power supply
[16:00] <jcoxon> i've been looking for a give away like that for ages
[16:00] <neontube> plus all the satalite gear
[16:00] <jcoxon> half the reason i put up with hundreds of freecycle emails
[16:01] <neontube> lol
[16:02] <neontube> well so far i have found 1 reciver box, 3 interface boxes (convert to the BBC user interface) and one down converter for the old dish
[16:03] <jcoxon> cool
[16:03] <neontube> but i deffinatly used to have another reciver
[16:04] <neontube> as i remeber the monitor speaker had come unglued from the case, and te one thats currently bleeping on my desk is intact
[16:07] <jcoxon> signal getting stronger?
[16:08] <neontube> seems to be
[16:08] <neontube> but the antenna is in the loft so i don't expect great things
[16:09] <jcoxon> :-)
[16:10] <jcoxon> well it should have risen now
[16:10] <neontube> it should sound like this
[16:10] <neontube> http://homepages.tesco.net/~a.wadsworth/NOAA.wav
[16:11] <jcoxon> very repetitive
[16:11] <neontube> ooo getting it now
[16:12] <neontube> very shitty and noisey
[16:12] <neontube> will move antenna out to the garden tommorow ;)
[16:13] <jcoxon> j pass is some java software to predict the sat passes
[16:16] <neontube> oooo right over head now and getting some fairly good signal
[16:17] <neontube> deffinatly need to move the antenna outside though
[16:18] <neontube> jcoxon: u got a link to that software
[16:19] <jcoxon> J pass?
[16:19] <neontube> yer
[16:19] <jcoxon> http://science.nasa.gov/Realtime/JPass/20/
[16:19] <jcoxon> in control make sure to change the satellites to all
[16:25] <neontube> what did u get as my location frm that post code
[16:26] <jcoxon> yup
[16:26] <jcoxon> oh
[16:26] <jcoxon> one sec
[16:26] <jcoxon> 53.17 1.4004
[16:30] <neontube> off to b&q tommorow to get a wall bracket for the anteanna then :P
[16:31] <jcoxon> haha
[16:31] <jcoxon> guess weather sats could be considered high altitude :-p
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[16:32] <neontube> 3000km :P
[16:33] <jcoxon> that'll do
[16:34] <edmoore_> jcoxon:
[16:34] <edmoore_> whoops
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[16:34] <edmoore_> jcoxon: with the gm8blah modules, on the breakout board, with their smd connector to the pcb, does the chassis still mount flush to the board?
[16:35] <jcoxon> yes
[16:35] <jcoxon> the breakout board has some holes to poke the little case pins throught
[16:35] <jcoxon> though*
[16:36] <edmoore_> aha yep
[16:36] <edmoore_> 8 in total?
[16:36] <edmoore_> 3 each on one pair of opposite sides, 1 each on the other pair of opposites?
[16:38] <jcoxon> can't remember
[16:39] <jcoxon> i don't have it in front of me
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[16:39] <jcoxon> jatkins: hows it going?
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[16:39] <jatkins> was just gonna ask you for help :)
[16:39] <jcoxon> i just thought, are you using a transistor or wiring directly?
[16:40] <jatkins> wiring directly -- I was going to ask if you used a transistor
[16:40] <jcoxon> i didn't
[16:40] <jcoxon> but
[16:40] <jcoxon> i just realised that the arduino uses 5v and the camera most likely 3.3v
[16:40] <jcoxon> everything i use does 3.3v
[16:40] <jatkins> ok
[16:41] <jatkins> is it ok if I paste my code?
[16:41] <jcoxon> go for it
[16:41] <jatkins> int camGPIO = 12;
[16:41] <jatkins> void setup()
[16:41] <jatkins> {
[16:41] <jatkins> // nothing to setup
[16:41] <jatkins> }
[16:41] <jatkins> void loop()
[16:41] <jatkins> {
[16:41] <jatkins> pinMode(camGPIO, OUTPUT);
[16:41] Channel flood from jatkins -- kicking
[16:41] <jatkins> digitalWrite(camGPIO, LOW);
[16:41] jatkins kicked from #highaltitude by zeusbot: flood
[16:41] <edmoore_> haha
[16:41] <edmoore_> whoops
[16:41] <jcoxon> oops
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[16:41] <jcoxon> damn zeusbot
[16:41] <jcoxon> sorry jatkins
[16:41] <edmoore_> makes a cool noise
[16:41] <jatkins> lol
[16:41] <jcoxon> forgot that zeusbot is mean
[16:42] <edmoore_> just to loose the silly underscore, sorry everyone as i'm about to flood
[16:42] <edmoore_> l
[16:42] <jatkins> so I'm using GPIO 12 and the GND pin
[16:42] <edmoore_> l
[16:42] Last message repeated 8 time(s).
[16:42] Channel flood from edmoore_ -- kicking
[16:42] <edmoore_> l
[16:42] edmoore_ kicked from #highaltitude by zeusbot: flood
[16:42] <jcoxon> yup
[16:42] <jatkins> does the code look ok?
[16:42] <jcoxon> didnt' see it all :-)
[16:42] <jatkins> oh right
[16:42] <jcoxon> stick it on a page on the wiki and i'll have a look
[16:42] <jatkins> ok
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[16:43] <edmoore_> fun
[16:43] Nick change: edmoore_ -> edmoore
[16:44] <jcoxon> you enjoy that?
[16:44] <jatkins> http://wiki.ukhas.org.uk/camera_shutter_code
[16:44] <edmoore> yes, great fun
[16:44] <jatkins> lol
[16:44] <edmoore> I love the constipation adverts they show during countdown
[16:44] <jcoxon> jatkins: nope
[16:44] <jcoxon> i'll update it
[16:45] <jatkins> thanks
[16:46] <jcoxon> done
[16:46] <jcoxon> firstly you only need to setup the pin once as an output
[16:46] <jcoxon> so stick that in the setup bit
[16:46] <jatkins> ok
[16:46] <jatkins> I had it like that before
[16:46] <jcoxon> and then all you are doing is making the pin do 5v
[16:46] <jcoxon> sleep 500
[16:46] <jatkins> ok
[16:46] <jcoxon> then 0v
[16:47] <jcoxon> sleep 5000
[16:47] <jatkins> so 5v won't hurt the camera?
[16:47] <jcoxon> yeah it might
[16:47] <jcoxon> best to do a voltage divider
[16:48] <jcoxon> and i have to go so edmoore shall explain
[16:48] <jcoxon> cya all
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[16:48] <jatkins> ok
[16:48] <jatkins> edmoore: 'lil help? :)
[16:48] <edmoore> ok
[16:48] <jatkins> thanks
[16:48] <edmoore> helpfully, I know nothing about the arduino programming language...
[16:48] <jatkins> cool
[16:48] <jatkins> they have a nice reference on their site
[16:48] <edmoore> do you have any resistors?
[16:49] <edmoore> ok well that's cool then
[16:49] <jatkins> no
[16:49] <jatkins> but gpio 13 has a built in transistor
[16:49] <jatkins> ..but that probably won't help
[16:49] <edmoore> not for a voltage divider
[16:49] <jatkins> ok
[16:49] <edmoore> a voltage divider uses resistors to let you make a smaller voltage
[16:49] <edmoore> they're very simple
[16:49] <jatkins> oh, cool
[16:49] <edmoore> you stick two resistors in series
[16:50] <edmoore> we'll call them R1 and R2
[16:50] <jatkins> ok
[16:50] <edmoore> connecting the top one to 5V and the bottom one to 0V
[16:50] <edmoore> to basically 5V is connected by 0V but with two resistors end-t-end in between
[16:50] <jatkins> ok
[16:51] <jatkins> would I get a resistor from rapid?
[16:52] <edmoore> yep
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[16:52] <edmoore> anywhere
[16:52] <jatkins> ok
[16:52] <edmoore> you can get an entire range of resisots
[16:52] <edmoore> you don't tend to by them in anything less than by the 50
[16:52] <edmoore> they're dirt cheap
[16:52] <jatkins> ok
[16:53] <edmoore> there we go: http://www.doctronics.co.uk/voltage.htm
[16:53] <edmoore> so basically you can make a smaller voltage by using the voltage in the middle of two resisots. that link explains it
[16:53] <jatkins> ok
[16:53] <jatkins> thanks
[16:53] <jatkins> http://www.rapidonline.com/products.aspx?tier1=Electronic+Components&tier2=Resistors+%26+Potentiometer
[16:53] <jatkins> which category do I need?
[16:54] <edmoore> http://www.rapidonline.com/productinfo.aspx?tier1=Electronic+Components&tier2=Resistors+%26+Potentiometer&tier3=Metal+Film+Resistors&tier4=MR25+Metal+film+resistor+kit&moduleno=65199
[16:54] <jatkins> thanks
[16:54] <edmoore> that'll keep you going for years
[16:55] <jatkins> yep
[16:56] <jatkins> I should probably just buy a pack and leave it for now then
[16:56] <jatkins> (until it comes)
[16:56] <edmoore> ok
[16:56] <edmoore> however
[16:57] <edmoore> infact don't worry
[16:57] <edmoore> what camera have you got?
[16:57] <jatkins> vivitar vivicam 3720
[16:57] <jatkins> i'll get you a link
[16:58] <jatkins> http://www.ciao.co.uk/Vivitar_ViviCam_3720__6661504
[17:02] <Laurenceb> hi all
[17:02] <jatkins> hi
[17:02] <neontube> ello
[17:02] <neontube> LB, u missed the exciting weather satellitte passing over earlier
[17:02] <neontube> :p
[17:03] <Laurenceb> :D
[17:04] <Laurenceb> my HVB supply has too much ripple :S
[17:04] <edmoore> jatkins: probs best to leave it until jcoxon comes back - he's done it before and I wouldn't want to advise you of anything without being sure it wouldn't break your cam
[17:04] <Laurenceb> HV*
[17:04] <neontube> if anyone is ordering anything in the next week or so from an electronics firm, i need a 137.100 meg xrtl
[17:04] <edmoore> that's pretty high
[17:04] <Laurenceb> yes
[17:04] <jatkins> edmoore: ok, thanks for your help
[17:05] <neontube> its another one of the weather satelites, means i can upgrade this reciver
[17:06] <Laurenceb> I was looking into HFterm the other day
[17:06] <Laurenceb> for recieving
[17:06] <neontube> cool
[17:06] <Laurenceb> there also MMTTY
[17:07] <Laurenceb> but thats windows only
[17:08] <Laurenceb> jcoxon: is that arduino code?
[17:09] <jatkins> http://wiki.ukhas.org.uk/camera_shutter_code ?
[17:09] <Laurenceb> yes
[17:09] <jatkins> yep
[17:09] <Laurenceb> I see
[17:09] <Laurenceb> why dont you try c?
[17:09] <Laurenceb> its hardly any harder
[17:10] <jatkins> don't have a pic
[17:10] <Laurenceb> nah, for your arduino
[17:10] <jatkins> didn't know you could
[17:10] <jatkins> have you done it?
[17:11] <Laurenceb> I think you will be able too, it might be worth looking into, once you've got some more experience
[17:11] <jatkins> ok, thanks
[17:11] <jatkins> you can delete the page
[17:11] <Laurenceb> no, I've been using the chips on breadboard
[17:11] <Laurenceb> ?
[17:11] <jatkins> it was just to show jcoxon my code
[17:11] <Laurenceb> why its useful
[17:11] <jatkins> ok
[17:11] <Laurenceb> soory I wasnt being uptight
[17:12] <jatkins> np
[17:12] <jatkins> it's not a final version
[17:12] <jatkins> doesn't work
[17:12] <Laurenceb> :(
[17:12] <jatkins> at least it might hurt the camera
[17:12] <Laurenceb> have you tried it with an led?
[17:13] <jatkins> i've done the example code on pin 13
[17:13] <jatkins> i don't have a led on its own
[17:13] <Laurenceb> are there leds on the board?
[17:13] <jatkins> yep
[17:13] <jatkins> one is connected to gpio 13 for testing
[17:14] <Laurenceb> I see, so your flashing it?
[17:14] <jatkins> have done before, but that code was to trigger camera shutter
[17:14] <jatkins> i'm gonna use a resistor now though
[17:15] <jatkins> http://wiki.ukhas.org.uk/camera_shutter_code?rev=1199465116
[17:15] <Laurenceb> well if your sure about the camera interface, you should be fine :D
[17:15] <jatkins> :)
[17:16] <Laurenceb> but I'd get a multimeter to check out the camera with
[17:16] <Laurenceb> you can pick them up for £5 or so, and the cheap ones seem to work ok
[17:17] <jatkins> ok
[17:18] <Laurenceb> I know it probably looks expensive, but if you equip yourself with a few parts, e.g multimeter, good iron, resistors, breadboard, leds, capacitors, you'll be sorted
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[17:20] <[1]jatkins> sorry about that
[17:20] <[1]jatkins> internet went off
[17:22] <edmoore> Laurenceb: here here
[17:22] <[1]jatkins> I was thinking of using custom-built lightweight helium tanks instead of a balloon
[17:22] <[1]jatkins> and just venting it at altitude
[17:23] <Laurenceb> ?
[17:23] <edmoore> getting a few useful tools and parts
[17:23] <[1]jatkins> don't know if it would work
[17:23] <Laurenceb> as a physicist i can say that will not work
[17:23] <[1]jatkins> oh
[17:23] <Laurenceb> sorry
[17:23] <[1]jatkins> too low air pressure?
[17:24] <Laurenceb> the tanks would be way too heavy
[17:24] <Laurenceb> way way waaaayyyyy to heavy
[17:24] <[1]jatkins> oh
[17:24] <edmoore> well no - helium works because at a given pressure, it weighs less than air
[17:24] <[1]jatkins> would a lightweight material just burst?
[17:24] <edmoore> this is true for almost any given pressure
[17:25] <Laurenceb> imagine a 1L bottle filled with hemium, that will lift about a gram
[17:25] <edmoore> now you have to contain it somehow
[17:25] <[1]jatkins> ok
[17:25] <edmoore> but in a way that lets it be at the same pressure as outside
[17:25] <edmoore> or near enough the same pressure as outside
[17:25] <[1]jatkins> sorry - I meant wouldn't the low air pressure cause a lightweight material to burst
[17:26] <Laurenceb> a "material" wont "burst"
[17:26] <edmoore> no, it's just that 'tanks' sort of implies you're storing it at a higher pressure
[17:26] <[1]jatkins> oh
[17:26] <Laurenceb> theres a difference between solids liquids and gasses
[17:26] <edmoore> you don't want that, you want it to be at the same pressure as the outside, or close to it
[17:26] <[1]jatkins> ok
[17:26] <edmoore> and that means you have to let it expand as it goes up so it keeps close the the same pressure as the outside
[17:27] <[1]jatkins> oh, ok
[17:27] <edmoore> and it just so happens that a balloon is about the best way to do that
[17:27] <edmoore> it's a light, stretchy tank
[17:27] <[1]jatkins> ok
[17:27] <edmoore> at sea level, air has a mass of about 1.22kg per cubic meter
[17:27] <[1]jatkins> ok
[17:28] <Laurenceb> jatkins: http://www.apqj64.dsl.pipex.com/sfa/slg_structure.htm
[17:28] <edmoore> at sea level, helium has a mass of about 0.22kg per cubic metre
[17:28] <Laurenceb> that might help explain the basics
[17:28] <[1]jatkins> thanks
[17:29] <edmoore> so at sea level (which means, at the pressure and temperature you get at sea level) then 1 cubic meter of helium will have a bouyancy of about 1kg
[17:29] <[1]jatkins> ok
[17:29] <edmoore> because 1.22 - 0.22 = 1
[17:29] <[1]jatkins> yep
[17:29] <edmoore> so as you go up, the pressure decreases
[17:29] <[1]jatkins> yeah
[17:29] <edmoore> the air at 30km has a mass of about 0.006 kg per cubic meter
[17:29] <[1]jatkins> ok
[17:30] <edmoore> if you keep the helium stored in the same tank, which can't expand, so is at a fixed pressure, it'll still have a mass of 0.22kg per cubic metre
[17:30] <[1]jatkins> so it won't provide lift?
[17:30] <edmoore> so the helium will have a much higher mass per cubic meter (density) that the surrounding air, and the thing would sink
[17:30] <[1]jatkins> ok
[17:31] <[1]jatkins> I was thinking of building a buoyancy system to stay aloft for a long time
[17:31] <edmoore> so you have to let the helium pressure stay the same as the otuside pressure, and a stretchy latex balloon is a good way of doing that
[17:31] <[1]jatkins> yep
[17:31] <edmoore> you'd need a balloon too
[17:31] <[1]jatkins> yeah
[17:31] <edmoore> you could store some extra helium in tanks though
[17:31] <[1]jatkins> ok
[17:31] <edmoore> but it's complicated, and probably best left until you reach that stage
[17:31] <[1]jatkins> ok
[17:32] <edmoore> you'll get the scientific background for it in no time, don't worry
[17:32] <[1]jatkins> was thinking of using pumps to compress at apogee, decompress at perigee basically
[17:32] <[1]jatkins> lol
[17:32] <[1]jatkins> so you wouldn't have to vent helium
[17:32] <Laurenceb> that is actually a good idea
[17:32] <Laurenceb> but hard to do in practice
[17:32] <[1]jatkins> yeah
[17:32] <[1]jatkins> the pumps would be quite heavy
[17:32] <Laurenceb> as you need a strong light weight tank and pump system
[17:33] <[1]jatkins> yep
[17:33] <[1]jatkins> it could be useful for a high altitude 'satellite' project for instance
[17:33] <edmoore> yes, it's all about that balance I was talking about before christmas between mass and energy
[17:33] <[1]jatkins> ok
[17:34] <edmoore> and this things only really become practical and much bigger (nasa style) scales. That's not to say it can't be done, but is much much hadrer to do at our scale
[17:34] <[1]jatkins> yep
[17:34] <edmoore> there's nothing wrong with the idea in theory, tbhough
[17:34] <[1]jatkins> ok
[17:34] <Laurenceb> yes, I think nasa have done experiments along those lines
[17:34] <[1]jatkins> i.e. it could be used for a project like spirtofknoxville atlantic crossing
[17:35] <[1]jatkins> they have a whole facility for balloons
[17:35] <Laurenceb> yes, thats very interesting
[17:35] <[1]jatkins> http://www.csbf.nasa.gov/
[17:35] <Laurenceb> I want to do something long duration
[17:35] <[1]jatkins> ...balloons that go up to 49km
[17:35] <[1]jatkins> an atlantic crossing would be very cool
[17:36] <Laurenceb> right I've gtg, cya all
[17:36] <[1]jatkins> cya
[17:36] <[1]jatkins> bbl
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[17:36] <[1]jatkins> thanks
[17:36] Nick change: [1]jatkins -> jatkins
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[21:22] <edmoore> evening everyone
[21:27] <natrium> hey edmoore
[21:28] <edmoore> how's it going?
[21:30] <natrium> not bad, you?
[21:31] <edmoore> pretty good. Fiddling the books so I can afford a telit module
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[22:32] <jcoxon> evening all
[22:40] <jcoxon> edmoore, hows planning to use the gm862 module
[22:41] <jcoxon> just thought, if you use the gm862-gps module you lose a serial port
[22:41] <edmoore> I really only want it as a dum gsm module
[22:42] <edmoore> wasn't planning on requiring the more clever pythony features
[22:42] <edmoore> although i'll build the option in to use them, even if it's just io holes
[22:42] <jcoxon> well don't get the gm862-gps
[22:42] <edmoore> but yes, I'm using it
[22:42] <edmoore> i won't
[22:42] <jcoxon> just get the gm862
[22:43] <jcoxon> they are pin compatible so it wouldn't take much to upgrade them
[22:43] <edmoore> it's a done deal
[22:43] <jcoxon> out of interest whats the cheapest you've found them?
[22:44] <edmoore> i'll team up with fnoble and tell the guys it's the only way forward and they need to pay for it
[22:44] <edmoore> i've not really looked beyond sparkfun
[22:44] <edmoore> interestingly, have you seen the gm864 pro?
[22:44] <edmoore> or 863 pro
[22:44] <edmoore> or something
[22:44] <jcoxon> no
[22:45] <edmoore> it's the size of the surface mount one, but it has a built in arm9 entirely for customer applications
[22:45] <edmoore> and they provide linux for it
[22:45] <edmoore> that really really is a flight computer on a chip
[22:45] <edmoore> and a very powerful one too
[22:46] <jcoxon> hmmm i can't find it
[22:47] <jcoxon> found it
[22:48] <jcoxon> oooo it is nice
[22:48] <jcoxon> yuk bga
[22:48] <edmoore> you could actually sticky tape it on its back and solder directly to the pins
[22:48] <edmoore> you wouldn't need half of them
[22:49] <jcoxon> they are all nice modules
[22:49] <jcoxon> slightly expensive but good modules
[22:49] <edmoore> yep
[22:50] <edmoore> it's depressing that they can put them in phones for probably £3
[22:53] <jcoxon> indeed
[22:55] <jcoxon> so for your black box you are going to use an ARM?
[23:01] <edmoore> yep
[23:02] <edmoore> lpc2148
[23:02] <edmoore> the box is sort of red and white, to be fair to it
[23:02] <edmoore> with a nice hinge
[23:03] <jcoxon> for arguments sake can't you get away with just using the gm862's python interpreter?
[23:09] <edmoore> for what?
[23:09] <jcoxon> as a flight computer
[23:10] <edmoore> it's not really suitable for real time control
[23:10] <edmoore> this is going to be a full flight computer, not just a balck box
[23:10] <jcoxon> okay
[23:10] <jcoxon> what happened to the black box :-)
[23:11] <edmoore> just it'll be simpler firmware for black box usage
[23:11] <edmoore> the hardware'll be there
[23:11] <edmoore> but there's not really a reason not to stick in the extra functionality. It's not like I'm using some flakey operating system :p
[23:12] <edmoore> actually i'm not sure flaky is a word one can desribe python with
[23:12] <jcoxon> i think the phrase is 'inappropriate'
[23:13] <edmoore> but anywho, i'll build it in if space permits. It's just some more IO pins that are already there
[23:13] <jcoxon> for embedded at least
[23:14] <jcoxon> well perhaps i could put some code for you
[23:14] <jcoxon> and you could make the main processor hold a gpio line to gnd
[23:14] <jcoxon> if it goes high or floats or something
[23:14] <jcoxon> the gm862 processor takes over
[23:15] <jcoxon> and just does very simple gps -> sms
[23:15] <edmoore> that's what I was thinking....
[23:16] <edmoore> there's a goos safety net there
[23:17] <jcoxon> some sort of loop that every 10secs check a gpio for its status
[23:17] <jcoxon> if its high it just runs some sort of firefly like code
[23:19] <edmoore> the arm won't ever hang
[23:19] <jcoxon> ha
[23:19] <edmoore> no seriously, it's got 2 hardware watchdogs
[23:20] <edmoore> it'll reset itself if the hardware watchdog isn't pinged occassionally. it's exactly as you describe but just within the chip
[23:21] <edmoore> it resets the chip, even
[23:21] <jcoxon> well that rules out my input to the project :-p
[23:21] <edmoore> I mean there's probably 9000 times for change of a python script hanging than this hanging, so the safety net should probably be the other way round - but that's not a luxury we have :)
[23:22] <edmoore> 9000 times more chance of a*
[23:22] <edmoore> lol no, I do quite want to use the pythons tuff
[23:22] <edmoore> I'm just not sure what for yet...
[23:22] <jcoxon> whatever
[23:22] <jcoxon> you just feel sorry for me
[23:22] <jcoxon> :-p
[23:22] <edmoore> ha
[23:22] <edmoore> well there's all that gpio
[23:23] <edmoore> I dunno. we'll see how it goes. Need to sit down with a piece of paper and plan it all
[23:23] <jcoxon> :-)
[23:23] <jcoxon> twas just teasing
[23:30] <natrium> jcoxon, when's firefly II launch? :P
[23:30] <jcoxon> oooo when its finished :-)
[23:31] <jcoxon> but in a couple of weeks, soon
[23:31] <jcoxon> i've got exams in a week so thats slightly in hte way
[23:31] <jcoxon> but after that
[23:31] <jcoxon> ...
[23:31] <natrium> Real Soon (TM)
[23:31] <jcoxon> i've rigged the camera
[23:31] <natrium> lectures start on monday :/
[23:32] <jcoxon> so got to finish the code, make the radio transmitter and also interface teh data logger
[23:32] <natrium> yeah, better finish the code before it finishes you
[23:32] <natrium> sorry, i went edmoore there
[23:32] <jcoxon> haha
[23:32] <jcoxon> actually the code is coming along nicely
[23:32] <jcoxon> considering its about version 7 of yours and Nick's code
[23:33] <edmoore> am I an adjective now?
[23:33] <natrium> looks like it :P
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[23:38] <Laurenceb> hi all
[23:46] <edmoore> hi lb
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[23:52] Nick change: jcoxon_ -> jcoxon
[00:00] --- Sat Jan 5 2008