highaltitude.log.20090220

[00:04] <Laurenceb> hi hallam
[00:04] <Laurenceb> http://www.youtube.com/watch?v=_RF21pfxJ8s
[00:06] <hallam> thanks, that will definitely help me get work done
[00:06] <Laurenceb> :P
[00:06] <jcoxon> hallam, a 30 day trial of python?
[00:06] <jcoxon> can't you get it free?
[00:07] <hallam> I looked closer and it's free forever for educational users
[00:07] <jcoxon> oh okay
[00:07] <hallam> this particular distribution, I mean
[00:09] <hallam> the damned auto-throttling network connection slows down over the course of downloading a 350MB file
[00:09] <hallam> starts off at 400kB/s and ends up around 40
[00:09] <hallam> it's like it's teasing me
[00:09] <SpeedEvil> hallam: are you doing other things with your connection?
[00:10] <hallam> no, it's the college limiting my bandwidth because they're stingy bastards
[00:10] <hallam> if you actually go over 1GB in 24hrs, they cut you back to sub-dialup speed
[00:10] <SpeedEvil> ah
[00:11] <hallam> and I pay 50GBP a term for this
[00:13] <SpeedEvil> My DSL connection is just unreliable enough that it typically has an IP profile of ~500K, even though 95% of the time it's at 2500.
[00:13] <SpeedEvil> OTOH - new phone line segment soon
[00:13] <jcoxon> ping natrium42
[00:20] <SpeedEvil> http://www.clusterballoon.com/ChairwayToHeaven.asp
[00:26] <Laurenceb> looks expensive
[00:27] <shellevil> yep
[00:29] <natrium42> jcoxon, hey
[00:29] <natrium42> SpeedEvil, http://natrium42.com/temp/schematic.pdf
[00:29] <jcoxon> natrium42, got hysplit automated
[00:29] <natrium42> ooh, nice :)
[00:30] <jcoxon> 24th looks good still off today's data
[00:30] <natrium42> SpeedEvil, please punch me if anything is wrong
[00:30] <natrium42> if anybody else has comments, let me know too
[00:37] <shellevil> looking
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[00:46] <shellevil> Sorry - not really able to do very critical scrutiny. The only thing that pops out immediately is is the LED resistors appropriate?
[00:46] <shellevil> they're red?
[00:47] <shellevil> The micro is specified for ~10-15mA output?
[00:49] <natrium42> yes, that should be fine
[00:49] <natrium42> you think resistors are not required?
[00:50] <shellevil> No - I think they're required, just checking the value - I don't know the micro, so don't know if 10-15mA is OK
[00:51] <natrium42> oh
[00:51] <natrium42> i just put random values for them
[00:51] <natrium42> going to calculate the resistance once i decide which LEDs to use
[00:53] <shellevil> By OK - I mean does not exceed recommended limits.
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[00:57] <hallam> Hi fergusnoble
[00:58] <fergusnoble> hallam: hello, hows it going?
[00:58] <fergusnoble> still want python fun?
[00:58] <hallam> alright, just trying to get to grips with python
[00:59] <hallam> sure, if you're keen for an hour or so, but feel free to sleep instead :)
[01:01] <fergusnoble> yeah, im happy to do an hour or so but i should sleep at some point
[01:01] <fergusnoble> be over in a sec
[01:01] <fergusnoble> should i bring my lappy?
[01:02] <natrium42> shellevil, ok thanks for checking!
[01:02] <hallam> if you like, or we can use mine
[01:02] <hallam> I plan on sleeping at 2ish
[01:02] <fergusnoble> ok, i wont bother then cos its a bit of a hassle
[01:02] <fergusnoble> be right over
[01:16] <natrium42> hey hallam, thanks for the email
[01:17] <natrium42> it's about 900 km :S
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[02:25] <hallam> hey natrium42
[02:25] <hallam> ouch, that's quite the long haul
[02:25] <hallam> if I were you I'd just ask Mark to package them carefully with a really obvious note to the customs dudes
[02:28] <hallam> g'night all
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[06:27] <natrium42> Laurenceb, how many copies of the PCB did you want again?
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[06:30] <natrium42> ah, two
[06:30] <natrium42> good good
[06:33] <natrium42> Laurenceb, your traces are too close to edge
[06:34] <natrium42> hehe, the routing is win -- looking into the mind of a madman :)
[06:37] <natrium42> i don't have time to wait for Laurenceb :(
[06:37] <natrium42> there seem to be a few problems with the PCB
[06:37] <natrium42> but i dunno if i can fix them without messing things up
[07:27] <Laurenceb> helloi
[07:27] <Laurenceb> sorry was zzz
[07:27] <Laurenceb> natrium42
[07:27] <Laurenceb> how much is there clearance off by?
[07:29] <natrium42> sorry, i already sent it off :(
[07:29] <Laurenceb> without the board?
[07:29] <natrium42> i may do another batch of PCBs after i receive this order
[07:29] <Laurenceb> ok, I dont mind
[07:29] <natrium42> yes, some of it is for my business & very time sensitive
[07:29] <Laurenceb> thanks for the help
[07:30] <natrium42> as for the fixes, i would put 24 mils between any trace and edge of pcb
[07:30] <Laurenceb> ok
[07:30] <natrium42> and keep minimum distance between traces to 7 mil
[07:31] <Laurenceb> yeah
[07:31] <Laurenceb> hadnt I already dont that?
[07:32] <Laurenceb> nvm I'll sort it
[07:32] <natrium42> near IC1, there's a trace too close to pad
[07:33] <natrium42> i can send you a .dru file i use
[07:33] <natrium42> you can use it to verify constraints
[07:33] <Laurenceb> ok, thanks
[07:36] <natrium42> sent
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[07:54] <natrium42> Laurenceb, i did order the gps pcbs for you though, so i am not all that bad
[07:58] <Laurenceb> :P
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[08:42] <jcoxon> morning
[08:44] <natrium42> hi jcoxon
[08:50] <jcoxon> hey natrium42
[08:51] <jcoxon> just running my hysplit script
[08:51] <jcoxon> its downloading the latest GFS to test :-p
[08:51] <jcoxon> do you perhaps have some ftp space i could upload them to?
[08:51] <jcoxon> which lists the files in a dir (my webserver doesn't do that and i can't be arsed to generate a page for them)
[08:58] <natrium42> sure, i could set that up
[08:59] <jcoxon> just need to list the files i guess as they'll be dated
[08:59] <jcoxon> (well the filenames are dates)
[09:00] <jcoxon> next step is to combine ht
[09:00] <jcoxon> oops
[09:00] <jcoxon> next step is to combine the traj paths with local weather
[09:09] <natrium42> and then we will be able to monitor it?
[09:10] <jcoxon> sort of
[09:29] <jcoxon> http://spacenear.us/gfs/
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[09:40] <jcoxon> natrium42, so basically i reckon i can give you 5/6 days warning of a potential oppurtunity
[09:41] <natrium42> that's very good
[09:41] <jcoxon> opportunity*
[09:41] <natrium42> should be enough time to prepare :)
[09:41] <jcoxon> okay what other things do we need to sort out?
[09:42] <jcoxon> you've sent off the pcb
[09:42] <jcoxon> guess we need to consider the logic for ballast dumping
[09:42] <natrium42> yes, a few hours ago
[09:42] <jcoxon> and also transmission gaps
[09:42] <jcoxon> as in every hour? every 3 hours?
[09:43] <natrium42> right, sat phone has limited number of minutes
[09:43] <natrium42> but spot/radio are unlimited
[09:44] <jcoxon> yeah but they are limited by power
[09:44] <natrium42> i should get some sleep
[09:44] <natrium42> g'nite
[09:46] <jcoxon> night
[09:46] <Laurenceb> hi
[09:47] <jcoxon> hey Laurenceb
[09:47] <Laurenceb> jcoxon: got a price for the valve yet?
[09:47] <jcoxon> no not yet
[09:47] <Laurenceb> ok
[09:47] <jcoxon> they wanted my address so they could send me a quote
[09:47] <jcoxon> Laurenceb, http://spacenear.us/gfs/
[09:47] <Laurenceb> natrium42: does your board have I2C ?
[09:48] <natrium42> yes
[09:48] <Laurenceb> cool, night
[09:48] <Laurenceb> 3.3v ?
[09:48] <natrium42> i put two connectors for I2C
[09:48] <natrium42> yes
[09:48] <Laurenceb> ok, the cap sensor IC uses 3.3v I2C
[09:48] <Laurenceb> thats the ballast sensing sorted :P
[09:48] <natrium42> good, lower voltage is better
[09:49] <jcoxon> Laurenceb, we are might need to have 2
[09:49] <natrium42> atmega has lower power usage if voltage is low
[09:49] <Laurenceb> oh we could add an electrolyte and some electrodes
[09:49] <jcoxon> dual ballast tank
[09:49] <Laurenceb> hmm
[09:49] Action: natrium42 Zzz
[09:49] <Laurenceb> I only have one sensor
[09:49] <Laurenceb> guess I could make another
[09:50] <jcoxon> the concept was as a redundency
[09:50] <Laurenceb> hmm
[09:50] <Laurenceb> I dont know
[09:50] <jcoxon> and so if the valve stayed open (which has happened before on a flight) we don't lose all the ballast
[09:50] <Laurenceb> yeah
[09:51] <Laurenceb> but the other valve might fail
[09:51] <jcoxon> true
[09:51] <Laurenceb> as we have so many cutdowns and arent going for very long duration we copuld go with dropped masses
[09:52] <jcoxon> i prefer the liquid ballast - we can regulate it a bit more
[09:52] <Laurenceb> how about an envelope temp sensor?
[09:52] <Laurenceb> yeah, and we have the tech to go for long duration
[09:52] <jcoxon> exactly
[09:53] <Laurenceb> shall we have an envelope temp sensor?
[09:53] <jcoxon> also by 2 ballast tanks it means that if the sensor went wrong we still know we've used only half
[09:53] <jcoxon> where would you put it?
[09:53] <Laurenceb> I have all the kit here to make one
[09:53] <jcoxon> at the vent ring?
[09:53] <Laurenceb> termocouple with trailing wire
[09:53] <jcoxon> the thing is you really don't want to mess around with the envelope
[09:53] <Laurenceb> maybe about 1m up the envelope
[09:53] <Laurenceb> yeah
[09:53] <jcoxon> even handling weakens it
[09:54] <jcoxon> and risks the long duration of the flight
[09:54] <Laurenceb> it would help with ballast drop calculation
[09:55] <jcoxon> also we might be quite far from teh envelop if we are going for a dipole vertical antenna
[09:55] <jcoxon> Laurenceb, yeah i agree
[09:55] <Laurenceb> http://wiki.ukhas.org.uk/_media/projects:first_design.png?cache=cache
[09:55] <Laurenceb> hhmm thats a good point
[09:55] <jcoxon> IR termomenter :-p
[09:55] <jcoxon> point it up and take readings :-p
[09:55] <Laurenceb> yeah, thats the best way
[09:56] <jcoxon> external temp would be definitely useful
[09:56] <Laurenceb> if you have peak heating and extern temp at nightfall you can come up with an accurate ballast drop
[09:56] <Laurenceb> drop say 70% of that, then record descent rate
[09:56] <Laurenceb> then do a secondary drop
[09:57] <Laurenceb> might want to do a small afternoon drop as well
[09:57] <jcoxon> yeah
[09:57] <jcoxon> an interesting point was made by teh guy who makes the balloons, more of a suggestion
[09:57] <Laurenceb> theres some papers on this
[09:58] <jcoxon> of at night purposely dropping to a low alt to keep warm
[09:58] <Laurenceb> hmm...
[09:58] <jcoxon> apparently icing of the envelope is a killer
[09:58] <Laurenceb> what to reduce icing?
[09:58] <jcoxon> yeah
[09:58] <Laurenceb> yeah I know
[09:58] <jcoxon> but i'm thinking that its a little too complicated
[09:58] <Laurenceb> I prefer to keep in the stratosphere
[09:58] <Laurenceb> yeah, lots to go wrong there
[09:58] <jcoxon> i agree, ride the winds
[09:59] <jcoxon> speed is better
[09:59] <Laurenceb> hmm I meant above tropopause
[09:59] <jcoxon> oh
[09:59] <jcoxon> hmmmm
[09:59] <jcoxon> i'm thinking a 11km alt
[09:59] <Laurenceb> can you run HYSPLIT at high alt?
[09:59] <Laurenceb> ~16Km
[09:59] <jcoxon> yeah
[09:59] <jcoxon> would you like me too...
[09:59] <Laurenceb> pls :P
[10:00] <jcoxon> let me just finish the bit of work - 10mins
[10:00] <Laurenceb> np
[10:03] <Laurenceb> I've got a PT100 sensor and an I2C ADC
[10:03] <Laurenceb> also humidity sensor and thermocouple
[10:06] <Laurenceb> Oh I just remembered, my origional design uses a sensortechnices pressure sensor
[10:07] <Laurenceb> its not absolutely essencial but would help for ballast drop control and altitude hold
[10:07] <jcoxon> you can get those from their webshop i think
[10:07] <Laurenceb> yeah, not the I2C
[10:08] <jcoxon> Laurenceb, so what alt?
[10:08] <jcoxon> 16km?
[10:15] <Laurenceb> yeah
[10:16] <Laurenceb> jcoxon: http://wiki.ukhas.org.uk/_media/projects:first_ideas.png?cache=cache
[10:25] <Laurenceb> annoyingly my level sensor uses two cap channels so I'm not sure if the humibity sensor can still be used
[10:29] <jcoxon> Laurenceb, http://spacenear.us/gfs/lb/
[10:30] <jcoxon> compare 2009-02-20-5.png in that dir to this one:
[10:30] <jcoxon> http://spacenear.us/gfs/2009-02-20-5.png
[10:34] <Laurenceb> yeah over twice as fast
[10:36] <jcoxon> i think 11km is the height we want to aim for to make it
[10:55] <Laurenceb> how is the altitude change computed?
[10:55] <Laurenceb> in hysplit?
[10:57] <jcoxon> that i don't know
[10:59] <jcoxon> there are quite a few articles online about how it all works
[11:30] <shellevil> envelope temp sensor - IR thermometer pointed up
[11:39] <Laurenceb> yeah, but it would need field of view restriction
[11:39] <Laurenceb> http://www.gyrocamsystems.com/images/product_views/pdf/DAT-C03-101508-ISR%20300.pdf
[11:39] Action: Laurenceb drools
[11:40] <SpeedEvil> I was meaning inside the envelope
[11:40] <Laurenceb> hmm ok
[11:40] <SpeedEvil> on the attach point
[11:41] <Laurenceb> may as well just use a thermocouple
[11:42] <SpeedEvil> To paraphrase jaws - gonna need a bigger balloon.
[11:42] <SpeedEvil> (for the cam)
[11:43] <Laurenceb> haha
[11:43] <Laurenceb> interesting that it uses mems IMU
[11:46] <jcoxon> hmmm why are we launching from canada? they have snow!
[11:47] <Laurenceb> so?
[11:47] <jcoxon> its going to be cold for natrium42 launching
[11:54] <SpeedEvil> So? He's a canadian, they are adapted to the cold. They all have a thick layer of blubber, and a luxuriant white coat of hollow fur, and big claws so they don't slide.
[11:57] <jcoxon> SpeedEvil, fair enough
[11:57] <jcoxon> have you seen my recent hysplit predictions? i've automated it all now
[11:57] <SpeedEvil> I sa<w the link you posted to flickr a couple of nights ago, looked good.
[11:58] <SpeedEvil> I think you hadn't finished then
[11:58] <jcoxon> http://spacenear.us/gfs/
[11:58] <jcoxon> basically everyday it does 6 days worth of forecasts based on the latest data
[11:59] <SpeedEvil> That's neat.
[12:00] <jcoxon> does require downloading 600mb of GFS data
[12:00] <SpeedEvil> per day?
[12:00] <jcoxon> so only once a day methinks (they release new stuff every 3 hours)
[12:00] <jcoxon> 600mb for one set, which is released every 3 hrs
[12:01] <SpeedEvil> what format is it in?
[12:01] <SpeedEvil> broken down wind vectors in voxels?
[12:01] <SpeedEvil> or something?
[12:01] <Laurenceb> how much does it change between uopdates?
[12:01] <jcoxon> its from the ARL ftp server and is converted to work with hysplit already
[12:01] Action: SpeedEvil passes Laurenceb a buggerfly flapping its wings.
[12:01] Action: SpeedEvil sighs.
[12:01] Action: jcoxon takes the easy route
[12:02] <jcoxon> Laurenceb, thats sort of the point of my system, we can see how it changes as we get closer to good days
[12:02] <Laurenceb> cool
[12:02] <jcoxon> e.g. i'm keeping an eye on the 24th/25th as i predict that would have been a good day to launch
[12:02] <Laurenceb> cant you run it on past data?
[12:02] <jcoxon> yeah
[12:02] <jcoxon> but we want to see its forecasting magic
[12:03] <jcoxon> anyone can run the past data
[12:03] <jcoxon> just need to register to run forecast stuff
[12:09] <SpeedEvil> Laurenceb: I'm on linux, and want to try dominoex and ... over GSM circuits. What's the easiest software that I can generate and recieve from wavs or other sound files?
[12:09] <jcoxon> audacity?
[12:10] <SpeedEvil> err - no
[12:11] <SpeedEvil> generate and recieve dominoex from sound files
[12:11] <jcoxon> fldigi then
[12:11] <jcoxon> you can generate to a wav file and also read wav files and decode
[12:12] <SpeedEvil> thanks
[12:12] <SpeedEvil> Wondering about using this. http://www.dealextreme.com/details.dx/sku.19634
[12:13] <jcoxon> dial up and transmit data across?
[12:13] <jcoxon> just using voice
[12:14] <jcoxon> cool idea
[12:14] <jcoxon> there are probably better formats though then dominoEx especially if you are generating it on linux
[12:21] <SpeedEvil> probably.
[12:22] <SpeedEvil> Problem is GSM is a very nonlinear medium.
[12:22] <SpeedEvil> To get decent datarates across it takes heroic efforts.
[12:22] <SpeedEvil> (synthetic voicebox driven by data, and voice recognition on the other end for ~1300bps)
[12:24] <jcoxon> i guess the bug is one way as well
[12:24] <SpeedEvil> yeah
[12:24] <SpeedEvil> Unless you poke into it.
[12:24] <jcoxon> hehe
[12:25] <SpeedEvil> Of course, it's quite possible to open it up, and do GPRS, or ...
[12:25] <SpeedEvil> But, it's not very easy
[12:26] <jcoxon> telit modules might be a little easy though a little more expensive
[12:27] <SpeedEvil> Voice isn't that bad.
[12:27] <SpeedEvil> If you're just using it as a near/post-landing locator
[12:28] <SpeedEvil> 50bps or so, and you get a position every second or 5.
[12:34] <jcoxon> could just use cell phone tracking
[12:37] <Laurenceb> back
[12:37] <Laurenceb> sorry, was at lunch
[12:37] <Laurenceb> SpeedEvil: GSM has a data mode
[12:37] <Laurenceb> not sure if you can actually use it...
[12:38] <Laurenceb> SpeedEvil: DTMF
[12:41] <Laurenceb> ~80 bps
[12:41] <Laurenceb> http://en.wikipedia.org/wiki/Goertzel_algorithm
[12:48] <SpeedEvil> yes, I'm wondering about minimal stuff though, which needs no soldering.
[12:49] <Laurenceb> whats wrong with DTMF?
[12:50] <SpeedEvil> I'm unsure DTMF will go through
[12:50] <Laurenceb> this is what its designed for
[12:50] <Laurenceb> well.... its used through GSM
[12:50] <SpeedEvil> It's not really
[12:50] <SpeedEvil> As I understand it, all GSM modems send it out of band
[12:50] <Laurenceb> when you ring up call centers ect
[12:50] <SpeedEvil> they say 'play 1' to the codec on the other end.
[12:51] <Laurenceb> oh ok
[12:51] <Laurenceb> so cant you get a modem to do that?
[12:51] <SpeedEvil> Also - there is an obvious benefit to being able to use the same format
[12:51] <SpeedEvil> of course.
[12:51] <SpeedEvil> (as radio)
[12:51] <Laurenceb> hmm
[12:51] <SpeedEvil> I'm wondering about cheap and easy ballooning.
[12:52] <SpeedEvil> A way to add GSM location to your payload very cheaply
[12:52] <Laurenceb> can you use AT commands to send DTMF then?
[12:52] <SpeedEvil> and without any hacking.
[12:52] <SpeedEvil> yes, that means opening the device, and locating the serial outs, and ...
[12:53] <Laurenceb> unless its got a port
[12:53] <SpeedEvil> it's not - power and mic is the only thing
[12:53] <Laurenceb> http://developer.sonyericsson.com/thread/23359
[12:54] <Laurenceb> get an ericsson
[12:54] <Laurenceb> they have 3.3v serial on the bottom
[12:54] <Laurenceb> also 3.3v power out :P
[12:55] <SpeedEvil> SE >31g and >3*3*2cm
[12:55] <SpeedEvil> and >$29
[12:55] <Laurenceb> hmm
[12:56] <Laurenceb> if your prepared to add a bit off mass you can get a phone
[12:56] <Laurenceb> ~85 grams
[12:56] <Laurenceb> enough power for gps and uC as well
[13:02] <SpeedEvil> Or ~10s -> 8g
[13:13] <SpeedEvil> www.smscom.cn/chi/content/download/338/1871/file/WM_PRJ_P5186_PTS_001-001.pdf - Similar pages -
[13:13] <SpeedEvil> is the docs
[13:19] Action: Laurenceb is too busy finding doppler residuals
[13:20] <SpeedEvil> ?
[13:20] <SpeedEvil> you mean trying given residual dopplers with a position solution to work out which ones are more real?
[13:23] <Laurenceb> no, looking at clock drift
[13:24] <SpeedEvil> ah
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[15:28] <Laurenceb> hi edmoore
[15:38] <edmoore> hi Laurenceb
[15:38] <edmoore> all well with you?
[15:50] <Laurenceb> hmm
[15:50] <Laurenceb> su[ppose so
[15:51] <Laurenceb> thinking of applying for: http://www.physics.ox.ac.uk/pp/Ericsson%20Industry.pdf
[15:52] <SpeedEvil> Sounds like fun.
[15:53] <Laurenceb> so did this :-S
[15:55] <edmoore> and giving up with sstl?
[15:57] <edmoore> Laurenceb: ping
[15:57] <edmoore> oh crap, I have a supervision
[15:57] <edmoore> oh no wait, it's 4.30
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[16:13] <jcoxon> afternoon
[16:14] <Laurenceb> sorry was afk
[16:14] <Laurenceb> hi jcoxon
[16:14] <Laurenceb> edmoore: yeah
[16:14] <edmoore> hi jcoxon
[16:14] <jcoxon> ooh hello
[16:15] <edmoore> is that like hello++?
[16:15] <jcoxon> :-)
[16:15] <jcoxon> sort of
[16:16] <jcoxon> encompases al
[16:16] <jcoxon> all*
[16:16] <jcoxon> edmoore, hows your week been?
[16:16] <edmoore> busy
[16:16] <edmoore> lots of work from out of no-where, + the knoweledge that i won't get much done this weekend
[16:16] <edmoore> and you?
[16:17] <jcoxon> useless week, beginning of a rotation so lots of introduction and cancelled teaching
[16:17] <edmoore> such is life
[16:17] <jcoxon> indeed
[16:17] <jcoxon> next week will be better
[16:18] <edmoore> sounds like other exciting stuff is going on though
[16:18] <jcoxon> yeah
[16:18] <jcoxon> i got off my arse and started kicking people
[16:19] <edmoore> always good :)
[16:20] <jcoxon> so things are starting to get done
[16:20] <jcoxon> been playing lots with hysplit
[16:20] <jcoxon> if only we were ready...
[16:20] <jcoxon> http://spacenear.us/gfs/2009-02-20-5.png
[16:21] <edmoore> wow
[16:21] <jcoxon> i've got hyplit working on my laptop and automated it so that we can keep an eye on the forecasts, everyday its running forecasts for the next 6 days
[16:23] <edmoore> payload built?
[16:23] <jcoxon> ummm sadly not yet
[16:24] <jcoxon> pcbs were sent off this morning for the flight 'puter
[16:24] <edmoore> that was perhaps a slightly over-optimistic question
[16:24] <jcoxon> rocketboy is on hte case of teh HF transmitter
[16:24] <jcoxon> ordered the envelopes
[16:24] <jcoxon> and am waiting for a quote on valves for the ballast
[16:24] <edmoore> uhuh
[16:25] <jcoxon> thats about it really
[16:25] <edmoore> awesomeness
[16:26] <jcoxon> now i guess we wait...
[16:26] <jcoxon> :-p
[16:26] <Laurenceb> are we going for envelope tem sensing ?
[16:27] <jcoxon> Laurenceb, i'm not sure
[16:27] <jcoxon> there are quite a few factors
[16:27] <Laurenceb> IMO we at least want envelope temp or barometric pressure
[16:29] <jcoxon> would we link these into the ballast logic then?
[16:29] <Laurenceb> yes
[16:30] <edmoore> from the pov of an interested outsider, just having the info would be extrememly useful for future attempts. if it goes wrong, the info will let you figure out why, and not just keep guessing and failing a la snox
[16:30] <Laurenceb> yeah
[16:30] <jcoxon> that is very true
[16:30] <Laurenceb> actually pressure is not so interesting
[16:30] <Laurenceb> its envelope temp that would be really handy
[16:31] <jcoxon> (edmoore, you are more then an interested outsider, you are welcome to be fully involved!)
[16:31] <Laurenceb> Ive seen a few papers on this
[16:32] <jcoxon> Laurenceb, what sort of distance could you put on a temp sensor to get it to the balloon?
[16:32] <Laurenceb> doesnt matter too much for a thermocouple
[16:32] <jcoxon> would it interfere with the dipole antenna?
[16:32] <Laurenceb> you could use a 4 wire PT100
[16:33] <Laurenceb> hmm it would have to double as the antenna
[16:33] <Laurenceb> and the RF splitters may prove problematic
[16:33] <edmoore> jcoxon: given i seem to be struggling just to do CUSF stuff atm, could be tricksy!
[16:33] <Laurenceb> but it should be quite doable, I got all the oparts to build a splitter
[16:33] <jcoxon> edmoore, i understand, all input is welcome (no requirement)
[16:34] <jcoxon> hmmmm, you see the simpicity of a dipole antenna, one arm going up to the balloon the other hanging down attracts me
[16:34] <SpeedEvil> Wouldn't simply 3 or 4 IR thermometers be interesting? Pointing down, sideways, up (at the enveolpe)?
[16:35] <edmoore> you can end-fire the dipole just as easily too
[16:36] <Laurenceb> yeah, that'd be my plan
[16:36] <Laurenceb> yeah a thermopile at the envelope would be good
[16:37] Action: SpeedEvil wonders where he saw those nice thermopiles with lenses
[16:37] <Laurenceb> chartland electronics ?
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[16:38] <RocketBoy> BBL
[16:38] Nick change: RocketBoy -> RocketBoy|Away
[16:40] <Laurenceb> http://people.csail.mit.edu/jaffer/FreeSnell/polyethylene.html
[16:41] <Laurenceb> looks a bit transparent to use a thermopile
[16:44] <SpeedEvil> oh
[16:44] <SpeedEvil> right
[16:44] <SpeedEvil> polythene
[16:44] <SpeedEvil> I thought it was multi-layer
[16:45] <SpeedEvil> Yeah - they make lenses for far IR out of PE
[16:48] <jcoxon> Laurenceb, i'm not sure then what we should do, lets run it by everyone and see what they say
[16:49] <Laurenceb> yeah
[16:49] <Laurenceb> we should be able to control altitude fine without
[16:49] <jcoxon> thats the thingy
[16:49] <Laurenceb> I just like the idea of really optimal altitude control
[16:49] <jcoxon> oh i know
[16:49] <Laurenceb> drop the exact right amount ect
[16:49] <jcoxon> henry was suggesting that if we could have an uplink then we could update it on the fly
[16:50] <Laurenceb> neat
[16:50] <Laurenceb> http://www.englishrussia.com/images/cool_cars/11.jpg
[16:50] <jcoxon> maybe instead of a dipole we could use a j-pole or slim jim
[16:50] <jcoxon> and have the payload higher up
[16:50] <edmoore> use an end-fire dipole
[16:50] <SpeedEvil> Is it sane to assume that the temperature inside the envelope is equilibrated to the outside temp?
[16:50] <edmoore> you need the radial pattern
[16:51] <SpeedEvil> Hmm. Probably not in daytime.
[16:51] <Laurenceb> SpeedEvil: no, thats the point
[16:52] <SpeedEvil> little latex or something balloon inside the big one, to carry the thermocouple/...
[16:52] <Laurenceb> it heats during the day and vents helium
[16:52] <SpeedEvil> And make it so it doesn't touch the main envelope.
[16:52] <Laurenceb> peak heating is around 2pm
[16:52] <jcoxon> the balloon has a venting ring at the bottom
[16:52] <jcoxon> which you could easily attach it to
[16:52] <Laurenceb> then it drops of slowly before falling really fast at nighfall
[16:52] <SpeedEvil> ah.
[16:53] <Laurenceb> yeah but it needs to be up inside the envelope
[16:53] <jcoxon> whether you could get it any way further up the balloon without risking damage is a difficult on to answer
[16:53] <Laurenceb> exposed to the interior convective currents
[16:53] <Laurenceb> yeah
[16:53] <SpeedEvil> The envelope is simply polythene?
[16:53] <Laurenceb> yes
[16:53] <SpeedEvil> :/
[16:53] <SpeedEvil> (WRT IR)
[16:55] <jcoxon> cause we need the most intact balloon as possible to get anywhere near what we want to do
[17:00] <SpeedEvil> I suppose you could spray a bit with PVA or something.
[17:01] <SpeedEvil> But probably a bad idea to start messing with the enveolpe
[17:01] <Laurenceb> add CO2 to the helium
[17:01] Action: jcoxon orders no messing with the envelope :-p
[17:02] <SpeedEvil> I've wondered about that - though propane, not CO2
[17:02] <SpeedEvil> as propane at least has some lift.
[17:02] <SpeedEvil> Oh - He.
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[17:08] <SpeedEvil> Hmm
[17:09] <SpeedEvil> I suppose an integrated radiometer thingy - a teeny black balloon on a wire - would be easy.
[17:10] <SpeedEvil> But that doesn't quite get you back to temperature without a balloon model.
[17:13] <Laurenceb> Jcoxon: the pressure sensor we'd want is HDIB001ABY8H3
[17:13] <Laurenceb> slightly different to on the wiki
[17:14] <Laurenceb> http://www.sensortechnics.com/download/hdi-650.pdf
[17:15] <Laurenceb> doh
[17:15] <Laurenceb> HDIB001AUY8H3
[17:24] <jcoxon> nothing from here then?
[17:24] <jcoxon> http://www.sensortechnics.com/index.php?fid=1190&fpar=0&isSSL=0&aps=0&blub=f7f20b328f7dfaee583a0f465346bc51
[17:25] <Laurenceb> couldnt find anything to match our specs :-/
[17:26] <Laurenceb> need 3.3V, I2C, 10mB to 1 Bar, absolute pressure
[17:27] <jcoxon> oh okay
[17:27] <jcoxon> hmmm sensor tech are just slow at giving quotes
[17:27] <jcoxon> nothing at farnell?
[17:27] <jcoxon> back in 20mins
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[17:27] <Laurenceb> not I2C
[17:33] <SpeedEvil> Lots of 15mb+ - but analog
[17:36] <Laurenceb> time for the riotducks methinks
[17:37] <Laurenceb> http://www.impactlab.com/wp-content/uploads/2008/06/spotafake2.jpg
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[17:44] <rjharrison_> hi all
[17:44] <rjharrison_> any exciting news?
[17:47] <SpeedEvil> Yes, Laurenceb just posted http://www.impactlab.com/wp-content/uploads/2008/06/spotafake2.jpg
[17:47] <SpeedEvil> (or not)
[17:48] <Laurenceb> riotducks ftw
[17:49] <Laurenceb> not as funny as the russian disco http://englishrussia.com/images/russian_youth/10.jpg
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[18:09] <natrium42> Laurenceb, since when do you visit ER? :)
[18:09] <Laurenceb> ER?
[18:09] <Laurenceb> oh that site
[18:09] <Laurenceb> hehe its funny
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[18:12] <Laurenceb> I'm off, cya
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[22:55] <natrium42> jcoxon, paid for the PCBs
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[23:34] <Laurenceb> hello
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[00:00] --- Sat Feb 21 2009