highaltitude.log.20080718

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[09:06] <edmoore> kc0wys: greetings
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[09:51] mc- (n=mfcastle@cpc4-glfd1-0-0-cust538.glfd.cable.ntl.com) joined #highaltitude.
[09:52] <mc-> natrium42, got the serial logger, thanks
[09:56] <mc-> morning edmoore, been catching up on the logs, saw the kiteplane on rcgroups, looks nice
[09:56] <mc-> I think I gave you some fibreglass spars, have you seen them?
[09:57] <edmoore> mc-: I am going home this w/e
[09:57] <edmoore> Will have a look
[09:58] <mc-> it looks like a few mins works to build a wing, (I'm sure it isn't)
[09:58] <mc-> I'll see what John B has to say about that
[09:58] <edmoore> is this for a kite?
[09:59] <mc-> http://www.rcgroups.com/forums/showthread.php?t=368337
[09:59] <mc-> I just hate it when someone says they 'whipped up' this plane
[09:59] <edmoore> yeah, looks fun
[09:59] <edmoore> :)
[10:00] <edmoore> you could drop the whole thing on a wee drogue
[10:00] <edmoore> release the drogue and deploy the kite wing
[10:00] <mc-> it takes me weeks to build a ARTF plane
[10:00] <edmoore> and it would rock
[10:00] <edmoore> wait till retirement - you can do a John.
[10:00] <edmoore> Though John seems to have annoyingly enviable levels of natural talent
[10:01] <mc-> I can't wait til retirement, I want to do it now
[10:02] <edmoore> I guess it's a making time thing. Commit to a lathe, blood sweat and tears till you start making nice stuff, etc etc. I once read 5bears.com from start to finish, and it was pretty inspiring. That's the kind of mechanical standards we should aim for.
[10:03] fnoble (n=fnoble@chu-gw.churchillcambridge.co.uk) joined #highaltitude.
[10:03] <edmoore> hi fnoble
[10:03] <edmoore> good to see you
[10:03] <fnoble> hello, just got your foreward
[10:03] <fnoble> looks good
[10:03] <mc-> hi fnoble
[10:03] <fnoble> hi mc-
[10:03] <edmoore> fnoble: doesn't it!
[10:03] <fnoble> sitting in churchill bar atm
[10:04] <fnoble> like the old days
[10:04] <edmoore> Do you see what I mean about how it'd be nice to mass produce them and badgers?
[10:04] <mc-> enjoying holidays?
[10:04] <fnoble> waiting for the helium
[10:04] <edmoore> fnoble: is everything cleared with peter Kirwan?
[10:04] <edmoore> That mate hates suprises.
[10:04] <edmoore> man*
[10:04] <fnoble> think so, rob was dealing with it
[10:04] <fnoble> if he has to leave then he will introduce me
[10:05] <edmoore> double check - this is the kind of stuff that can go from having churchill available to not having churchill available.
[10:05] <edmoore> Who has a car?
[10:05] <fnoble> mc-: yeah going well, up in Camb playing with balloons and rockets
[10:05] <fnoble> how about you?
[10:06] <fnoble> edmoore: do yo have the link to the quadracopter vid?
[10:06] <fnoble> couldnt find it on engineering tv
[10:06] <edmoore> fnoble: yes will find - who is driving on wed?
[10:06] <fnoble> dunno, will have to see if the forecast stays good, and it looks like sf still hasn't sent my order!!
[10:06] <fnoble> grrrr
[10:07] <mc-> is that http://www.peterkirwan.com/ ?
[10:07] <edmoore> mc-: no.
[10:07] <edmoore> fnoble: http://www.wikio.co.uk/video/304542
[10:08] <edmoore> mc-: he's the maintenance manager at Churchill.
[10:08] <edmoore> But the kind of mine you need to keep happy in order to get anything at all done there.
[10:08] <edmoore> man*
[10:09] <mc-> Yes, I know Alan in the mfring eng dept, he helped me so much..
[10:10] <mc-> 5bears.com is impressive, but I'll never be able to do that sort of thing..
[10:10] <edmoore> fnoble: so you've started work on v1.2?
[10:10] <fnoble> yeah, a bit
[10:10] <edmoore> mc-: he couldn't until her started!
[10:10] <edmoore> he*
[10:11] <edmoore> fnoble: microSD?
[10:11] <fnoble> ive just been fixing the obvious things
[10:11] <fnoble> yp :)
[10:11] <fnoble> *yup
[10:11] <fnoble> saves so much space
[10:12] <mc-> 5bears even built his own spot welder...
[10:12] <edmoore> indeed!
[10:12] <edmoore> sapce enough for batt management and radio. wooooooooo
[10:12] <edmoore> oh we should have a looksee at xmegas, maybe
[10:12] <fnoble> brb
[10:13] <edmoore> they seem to have built in 12bit DACs - though they're not particularly proven yet.
[10:13] <edmoore> ok
[10:18] <mc-> now I know how a capacitive spot welder works, and I have a nice big cap in my junk box...
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[10:27] <edmoore> fnoble_ or fnoble, are you back?
[10:27] <edmoore> mc-: yep, very useful little tools!
[10:27] <edmoore> perfect for that RC turbine
[10:29] <fnoble_> hello again
[10:29] <fnoble_> just met peter
[10:29] <edmoore> fnoble: cool - how was he?
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[10:32] <edmoore> fnoble_: ping
[10:32] <fnoble_> he was ok, made sure i knew he was serious though
[10:33] <edmoore> cool. is the helium delivered?
[10:33] <fnoble_> hopefully everything goes smoothly, i see now why this could make or break our relations with churchill
[10:34] <fnoble_> nope, not yet
[10:34] <edmoore> His buzzwords are safety and common sense, so if you give off odours of them he'll be totally happy.
[10:34] <fnoble_> okk
[10:35] <edmoore> ok well it sounds like everything is cool.
[10:35] <fnoble_> im thinking for v1.2 of not bothering with the avr
[10:35] <edmoore> Sorry if I'm jumpy, I spent a lot of time trying to build a decent relationship with him during the ball.
[10:35] <fnoble_> the radio is working well off the onboard dac for now
[10:35] <edmoore> woah hang yourself on.
[10:36] <edmoore> really?
[10:36] <fnoble_> and i think we should increment more slowly
[10:36] <fnoble_> want to get the design off to be made asap too
[10:36] <edmoore> I'm fairly unconvinced you could run control lops and kalman filters at the same time as a 300 baud radio
[10:36] <edmoore> operating at a fairly reasonable duty cycle
[10:37] <edmoore> maybe we could make an external radio for when we run on other devices.
[10:37] <edmoore> actually wait
[10:37] <edmoore> we'd also loose the usart that that would free up
[10:37] <edmoore> making comms with servos very difficult
[10:38] <edmoore> I'm unconvinced.
[10:39] <fnoble_> well... version 1.3 can be made more suitable for running heavy kalman stuff
[10:39] <fnoble_> and without pulseshaping the radio uses very little resources
[10:39] <edmoore> what about the extra UART?
[10:39] <fnoble_> even with can be made very slim with some optimisation
[10:40] <edmoore> we'd be locking 1.2 out of running parafoils or other dynamic things
[10:40] <fnoble_> well, we still have an I2C and an SPI free in hardware and we can do software serial for slower async stuff
[10:40] <fnoble_> for now
[10:40] <fnoble_> well then could use an external radio on a para
[10:40] <fnoble_> what do we need the extra hardware serial port for?
[10:40] <edmoore> To run these robot servos
[10:41] <edmoore> which go at 1MBit
[10:41] <fnoble_> just the servos?
[10:41] <fnoble_> and they are async?
[10:41] <edmoore> they are async, and for the parafoil I think it would only be servos
[10:41] <edmoore> though having a space usart is very useful.
[10:41] <edmoore> spare*
[10:42] <edmoore> what's the reasoning for loosing the avr?
[10:42] <fnoble_> hmmm... well could make a board that runs the servos and radio that hangs off the i2c
[10:42] <fnoble_> it saves a lot of time and complexity
[10:42] <fnoble_> makes it less likely that the new board wil have problems
[10:43] <fnoble_> priority is to get a good stable board for the balloon asap
[10:43] <edmoore> well an avr needs a crystal, +V, 0V
[10:43] <edmoore> and it would run telit and radio
[10:43] <edmoore> so....
[10:43] <fnoble_> and a lot of re-routing all the stuff we have already done
[10:43] <fnoble_> would be happier to leave it
[10:44] <edmoore> if you put the pad down, we can just jumper direct to the telit and radio if we decide not to use the avr
[10:44] <fnoble_> not leave it long but wait until we have a good board in hand
[10:44] <fnoble_> we dont have much time to mess around
[10:44] <fnoble_> we need a good board ready to fly within a few weeks
[10:44] <fnoble_> ideally
[10:45] <fnoble_> ok, ill look into it some more
[10:46] <fnoble_> but even if you dont want to call it v1.2 and call it 1.15 instead, need to send of a design like today or maybe monday at the latest
[10:46] <edmoore> Well test the waters on the money front
[10:46] <fnoble_> and know that when it comes it will work pretty much streight away with the software we have already
[10:46] <edmoore> I mean there's nothing wrong with making one now and iterating faster, if we can afford it
[10:47] <edmoore> rather, if we can afford to make 1.3 when we want to.
[10:47] <fnoble_> yeah exactly, i dont think they will mind us spending the money on pcs
[10:47] <edmoore> So can this one have battery monitoring?
[10:47] <fnoble_> ill chat it through with the others though
[10:47] <edmoore> a battery warning/power save mode would be a useful thing.
[10:48] <fnoble_> *pcbs
[10:48] <fnoble_> but maybe its easy to add it on
[10:48] <edmoore> You know I have no objections to iterating incrementally, so long as we don't loose out on a 'new board' funding slot cos of this'n.
[10:48] <fnoble_> so you think the avr should hang off the spi bus
[10:48] <fnoble_> and leave the i2c for external stuff
[10:49] <edmoore> no
[10:49] <edmoore> i was thinking
[10:49] <edmoore> hang it off the i2c
[10:49] <edmoore> then use the avr's spi to drive a dac
[10:49] <edmoore> and usart to drive the telit
[10:49] <fnoble_> could even use one of the other dedicated spis on the arm to give a direct bridge
[10:49] <edmoore> as it has 1x spi, 1x i2c, 1x usart
[10:51] <edmoore> and then maybe for 1.3 there could be a higher speed link between arm and avr, and have a more conventional dual-chip arrangement - on does more cpu stuff, the other does more i/o
[10:51] <edmoore> one does*
[10:52] <edmoore> talk to me.
[10:53] <edmoore> also, who's gonna make it - these half-pric people?
[10:54] <edmoore> if you want a 2nd pair of eyes to look over routing, do send me some stuff.
[10:54] <fnoble_> edmoore: ?
[10:55] <edmoore> what are you questioning?
[11:00] <edmoore> fnoble_: do you know of any epoxy that is transparent to IR?
[11:01] <fnoble_> hmm, thats wierd, all your messages just came through in a block
[11:02] <fnoble_> hence my question mark - didnt get any replies till now
[11:02] <edmoore> oh sorry
[11:02] <edmoore> is this ok now?
[11:02] <fnoble_> dunno who will make it, prolly olimex
[11:02] <fnoble_> yeah seems better
[11:03] <fnoble_> and yes battery mgmt is a must for the next revision i think
[11:03] <edmoore> I guess soon we'll have to start think about/talk to henry about martlet flight computer too
[11:03] <fnoble_> just sucks without it
[11:03] <edmoore> yeah - it should at least be able to do all ballooning things properly
[11:03] <fnoble_> yeah, im looking at the $10 cmos cameras on sf
[11:04] <fnoble_> look nicer than the ones i was trying to use
[11:04] <edmoore> So will we have more IO be able to be broken out usefully?
[11:04] <edmoore> and is adjusting the position of the jtag too upsetting to contemplate?
[11:05] <fnoble_> i hope so
[11:05] <edmoore> also, more questions - do you think there's any merit in a simple LPF on the i/p to the radiometrix?
[11:05] <fnoble_> thinks like that are higher on my priority list
[11:06] <edmoore> ok - we should at least make this as perfect for ballooning as we can.
[11:06] <edmoore> Let's make up some cutdown pcbs then on the remeaining sace on the eurocard
[11:06] <edmoore> space* having difficulty typing atm.
[11:06] <fnoble_> i will send you the design before it gets sent off, don't worry
[11:07] <fnoble_> yup ok
[11:07] <mc-> btw I got an olimex PCB made at 0.8mm thick, it's only a few $ extra.
[11:08] <fnoble_> rob a was going to do some analysis on how effective an analogue RC lp filter would be on the radio input
[11:08] <fnoble_> but i think he put it on a back burner
[11:08] <fnoble_> may put on pads for it though
[11:08] <fnoble_> just in case
[11:09] <edmoore> ok - could jsut go for something about right and stick a micro pot on
[11:09] <edmoore> although I don't know how well they work at low tempts
[11:09] <fnoble_> yeah was going to look at making all the connectors come out at the ends
[11:09] <edmoore> yes was about to ask that
[11:10] <fnoble_> see... there is a lot to do to get what we already have polished before we start adding new stuff!
[11:10] <edmoore> something that makes it easier to itegrate into a box would be a good thing.
[11:11] <edmoore> maybe stick the jtag at one end and everything else at the other if that helps
[11:11] <edmoore> we shouldn't even need jtag once usb boot is working
[11:11] <fnoble_> yeah, will try that
[11:11] <edmoore> and if everything else is at one end, it makes it easier to integrate onto a front panel
[11:11] <fnoble_> well... need it to debug
[11:11] <fnoble_> yup
[11:12] <fnoble_> i think the sma for the radio will have to go at the other end
[11:12] <edmoore> oh for sure, but once we're into the more operational side of things
[11:12] <fnoble_> which i think is good, keeps the noisy things down one end
[11:12] <edmoore> as opposed to the dev side of things
[11:12] <fnoble_> away from the gps
[11:12] <fnoble_> yup
[11:12] <edmoore> agreed, though when it's all in a box?
[11:13] <fnoble_> will try and make the external connector bigger too
[11:13] <edmoore> I'd have though you'd ideally want one panel with all the connectors on
[11:13] <fnoble_> with more useful pins on it, like some analogue inputs and maybe the other spi or i2c if its easy to route
[11:13] <edmoore> 1 gps ant, one radio, one usb, and a bunch of i/o that our cutdown triggers can plug into
[11:13] <edmoore> and then maybe a D-type for everything else
[11:13] <edmoore> and LEDs!
[11:14] <edmoore> We'll need LEDs on the panel
[11:14] <fnoble_> we are approaching 4-layer territory with the routing though
[11:14] <fnoble_> :)
[11:14] <edmoore> it can be done w/o! we cn be ninja baout it
[11:15] <edmoore> I guess really you can have connectors coming off different bits of the board- as long as it all ends up in that front panel
[11:15] <edmoore> what are we making it out of? ali?
[11:15] <edmoore> can cam precision do anodizing?
[11:17] <edmoore> Oh, and remember the accelerometer footprint :D
[11:18] <fnoble_> yeah
[11:18] <fnoble_> i have a contact for anodising
[11:18] <fnoble_> if we need
[11:18] <fnoble_> do some really nice type 3 hard finishes
[11:19] <fnoble_> its rediculously tough, i had to scratch away the anodise at one point on the torch to make an electrical connection to the boday
[11:19] <edmoore> ok
[11:19] <edmoore> then we should laser etch badgerworks on it
[11:19] <edmoore> or something
[11:20] <fnoble_> was ver difficult, sandpaper and stanley knives wouldnt even mark it!
[11:20] <edmoore> what's your take on a single massive conectors vs more individual dedicated ones?
[11:21] <fnoble_> dunno, i think the board should maybe have very general one
[11:21] <edmoore> I think we'll always need cutdowns, so may aswell find a robust 3-pole connector and throw 3 of them on the front
[11:21] <edmoore> sure, but for the enclosure
[11:21] <fnoble_> and then the front panel can break it out to more specific ones for cutdowns, cameras etc
[11:21] <fnoble_> dunno
[11:22] <edmoore> enclosure = front panel
[11:22] <fnoble_> depends whetehr the cutdown boards are going in the warmbox too
[11:22] <edmoore> no
[11:22] <edmoore> they'll be potted and exposed to the elements - you want a short distance between the cap and the cutdown itself
[11:22] <fnoble_> well i think we should stick with our bus idea
[11:22] <edmoore> to help with losses and reduce the weight of high current wire needed
[11:23] <edmoore> well that's a fairly complex cutdown. Can we be sure on getting the lengths?
[11:23] <fnoble_> yup
[11:23] <edmoore> do we actually honestly really need more microchips in there?
[11:23] <fnoble_> in theory most things can just hang off the single 10way ribbon
[11:24] <fnoble_> maybe not :)
[11:24] <edmoore> yuck
[11:24] <edmoore> no no no
[11:24] <fnoble_> but it is useful for doing more clever things
[11:24] <edmoore> like what
[11:24] <fnoble_> like getting the cutdown to check continuity and measure current and voltage etc
[11:24] <edmoore> ok fair point
[11:25] <edmoore> can we have intelligence though that lets them be used discretely
[11:25] <edmoore> like 'line high for more than 1s - bang'
[11:25] <fnoble_> checking the igniter actually fired
[11:25] <edmoore> ok, so we need lines to each board then
[11:25] <edmoore> 2 for i2c, and 2 power
[11:25] <edmoore> agreed?
[11:26] <edmoore> 4 lines*
[11:26] <edmoore> good god I'm having typing issues
[11:28] <edmoore> how often will we need to daisy-chain one off another? I'm just thinking more of a start topology from the front panel might make sense
[11:28] <edmoore> so still have, say, 3 connectors on the front. We can find some decent 4-pin weatherproof miniature connectors easily enough
[11:28] <edmoore> and then things like temperature sensors can go on there too.
[11:29] <edmoore> or rather, they can use those connectors.
[11:29] <edmoore> and I guess we can find some i2c <> UART bridge chips if we ever get desperate.
[11:29] <fnoble_> why star not daisy?
[11:30] <edmoore> because I would imahine more often you don't need to plug another cutdown into the one that's near the balloon
[11:31] <edmoore> so say you have one cutdown you want going down to the bottom of the payload and you want another one up in the rigging, it's just a pita to have to plug one into the other
[11:31] <edmoore> you may aswell plug both into the front of the box
[11:31] <edmoore> you can do it daisy chain too - it's all transparent to the bus
[11:31] <fnoble_> but then put the flight computer in the middle of the cable
[11:32] <fnoble_> it doesnt have to be at the end
[11:32] <edmoore> what cable do you have in mind for this?
[11:32] <fnoble_> but yes i agress, its more flexible maybe to have a couple of connectors in parallel on the panel
[11:32] <fnoble_> ribbon cable i was thinking
[11:32] <edmoore> no.
[11:33] <fnoble_> i guess the connectors are a bit sucky though
[11:33] <fnoble_> but you can get sub-D connectors that crimp onto ribbon
[11:34] <fnoble_> anyway, from the boards point of view it doesnt care right?
[11:34] <edmoore> can't have ribbon cable flapping around in -60 and subject to lots of forces, and maybe rain. I think we'd want sealed environmental connectors - let me find a pic of the sort of thing I'm thinking
[11:34] <edmoore> no, it's just just an i2c bus o the board
[11:34] <fnoble_> i think i know what your thinking of
[11:34] <fnoble_> i agree actually
[11:34] <fnoble_> i wasnt thinking properly
[11:34] <edmoore> shielded cable at the very least
[11:34] <edmoore> if we've got meters of i2c cable exposed to the elements
[11:34] <fnoble_> yeah, with IP rated connectors
[11:35] <edmoore> it may be just about robust enough, but you don't want, say, the gsm antenna screwing it up
[11:35] <edmoore> which it almost certainly will
[11:35] <fnoble_> yup
[11:35] <edmoore> you can get thin 4-cored shielded (armoured braded even) cable.
[11:35] <edmoore> that will be able to cope with a 2-balloon type scenario
[11:35] <fnoble_> i think armoured would introduce needless weight
[11:35] <edmoore> where everything is going crazy around it
[11:36] <fnoble_> but something robust and very flexible certainly
[11:37] <fnoble_> also thinking i might but a batt for the gps on the board
[11:37] <fnoble_> or at least a connector
[11:37] <edmoore> it's not that heavy - the kind of stuff that the hlf to sma converter is made from
[11:38] <fnoble_> thats juts think coax
[11:38] <edmoore> yes, batt backup would be a good idea
[11:38] <fnoble_> shielded is good, but i mean armoured cable is very heavy
[11:38] <edmoore> is the sleeving not a mela braid?
[11:38] <fnoble_> yup
[11:38] gerard_mp (n=gerard@18.Red-79-146-100.staticIP.rima-tde.net) joined #highaltitude.
[11:38] <gerard_mp> hi?
[11:38] <fnoble_> i thought you meant the stuff wound with thick steel wires
[11:38] <fnoble_> hello
[11:39] <edmoore> fnoble_: nope
[11:39] <edmoore> I'm trying to find an example of what i mean
[11:39] <fnoble_> ok
[11:39] <gerard_mp> does anybody know where I could buy a parachute (in europe)
[11:39] <edmoore> yes
[11:39] <gerard_mp> we've seen that our one is too small... argh
[11:39] <gerard_mp> the payload will be 4kg
[11:39] <edmoore> there's an italien aerospace comapny that have just been told a load of thiers are scrap
[11:39] <edmoore> which has made my day
[11:40] <edmoore> hi gerard_mp, let's size this parachute up for you then
[11:40] <gerard_mp> what?
[11:40] <gerard_mp> ¿?
[11:40] <edmoore> what kind of landing velocity are you looking for, and if you're not sure (no reason you would be) then shall we work one out?
[11:40] <fnoble_> so they finally realised being 50mm out wasnt good enough tolerence for ESA then :)
[11:40] <gerard_mp> hmm maybe 5m/s
[11:40] <edmoore> fnoble_: something like that!
[11:40] <edmoore> ok
[11:41] <gerard_mp> the one I have is from the-rocketman
[11:41] <gerard_mp> 5ft model
[11:41] <fnoble_> gerard_mp: you came to the right place at the right time, edmoore is a bit of a parachute pro
[11:41] <gerard_mp> it's rated for 5ms/s -> 2.5kg
[11:41] <gerard_mp> :)
[11:41] <gerard_mp> hehe
[11:41] <edmoore> well, the equation of drag is this: D = density*velocity^2*Cd*Area
[11:42] <edmoore> where D = drag and Cd = co-efficient of drag (which describes how draggy a body is for a given area)
[11:42] <edmoore> a parachute is in equilibrium, so Drag = weight
[11:42] <edmoore> 4*9.8 = 50 Newtons weight
[11:42] <edmoore> Cd for a simple parachute will be about 0.8
[11:43] <edmoore> density at sea-level is 1.22
[11:43] <edmoore> oh wait, forgot a factor of a half
[11:43] <gerard_mp> ok
[11:43] <edmoore> 0.5*density*v^2*Cd*A
[11:44] <edmoore> 0.5*v^2*density is normally called 'q' - the dynamic pressure
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[11:45] <edmoore> so re-arranging, Area = weight/(1.22*0.5*0.8*25)
[11:46] <gerard_mp> but which material do u use?
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[11:46] <fnoble_> hi james
[11:46] <jcoxon> hey fnoble_
[11:47] <fnoble_> brb helium!
[11:47] <edmoore> = 4 square meters. Diameter = 2.25 square meters
[11:47] <edmoore> sorry, 2.25 meters - a big parachute
[11:47] <edmoore> material I would recommend is rip-stop nylon
[11:48] <gerard_mp> do u think it's better to buy it... because being my first flight I'm not really shure and I haven't got any model to follow
[11:48] <jcoxon> fnoble_, edmoore launch going ahead?
[11:48] <edmoore> perhaps more important is the shape. the Cd depends on the 'type' of parachute. The best thing to do is find a supply of parachutes first, see what kind of parachute they are (there are many many different types) and then re-run these calculations, knwing the actual Cd, to find the right diameter
[11:48] <edmoore> jcoxon: weather is crap
[11:49] <edmoore> postpone to wed
[11:49] <jcoxon> oooooooooooooooo
[11:49] <edmoore> gerard_mp: yes
[11:49] <jcoxon> :-p
[11:49] <edmoore> buy the first one
[11:49] <jcoxon> am i still invited?
[11:49] <edmoore> probs - i can't be there, upsettingly.
[11:49] <edmoore> unless they launch at like 4pm
[11:49] <edmoore> when I could probably get the time off work.
[11:50] <edmoore> so gerard_mp : let's find an online parachute seller.
[11:50] <gerard_mp> edmoore: do u know of any online shop?
[11:50] <gerard_mp> ok hehe thanks
[11:52] <edmoore> gerard_mp: whilst i am looking, I would also recomment padding the bottom and the corners of your payload
[11:52] <edmoore> with lots of foam
[11:52] <edmoore> it looks like you have some pointy bits, which will hurt even at 5m/s
[11:53] <edmoore> gerard_mp: does it have to be european?
[11:53] <gerard_mp> hmmm yes the external structure will break I know, but we''l try to put foam
[11:53] <gerard_mp> well it should send it fast hehe
[11:54] <edmoore> http://www.the-rocketman.com/chutes.html
[11:54] <edmoore> the 7ft parachute would be ideal
[11:55] <edmoore> ask them how long it would take to get it to you.
[11:55] <gerard_mp> yes, the shop where I bought a few months ago :)
[11:55] <gerard_mp> thanks edmoore
[11:56] <edmoore> aerocon systems wil be cheaper
[11:56] <edmoore> but they're not very fast on delivery
[11:58] <edmoore> http://www.redarrowhobbies.com/top_flight.htm
[11:58] <edmoore> the 90" one might be good
[11:58] <edmoore> crossform parachutes are quite stable - they do not oscillate much
[11:58] <edmoore> and you can build them yourself fairly easily
[11:59] <gerard_mp> the ones from rocketman are very nice
[11:59] <edmoore> yep. never used the, but they look pretty decent.
[12:00] <gerard_mp> do you make them yourself?
[12:00] <edmoore> gerard_mp: This summer I am working on the parachute landing system for ExoMars - so I have parachutes on the brain at the moment!
[12:01] <gerard_mp> I'd like to see some photos of yours to see how do u prepare them
[12:01] <edmoore> but these are fairly high tech parachutes designed for opening supersonically, and they are not that applicable to balloon payloads.
[12:01] <edmoore> Certainly - soon I will be flying a payload with a dual stage recovery
[12:01] <edmoore> so a small drogue to about 1000m, then a large main parachute
[12:02] <edmoore> as here in england wherever you go you are quite close to the sea, so we seek to minimise the drift in the wind on the way down.
[12:02] <gerard_mp> we'd like to launch our payload in 2 weeks but the parachute we have is not big enough argh....
[12:02] <edmoore> well if you could get some ripstop nylon, you could try and mke an X-form parachute
[12:02] <gerard_mp> like the ones from rocketman?
[12:02] <edmoore> also, there are other ways....
[12:02] <edmoore> your payload is 4kg right?
[12:03] <gerard_mp> yes
[12:03] <gerard_mp> so heavy hehe....
[12:03] <edmoore> indeed - but consider putting a large plat plate of blue polystyrene on the top
[12:03] <edmoore> say about 1M diameter
[12:04] <edmoore> let me work out how much drag that would give you...
[12:04] <edmoore> I'm just thinking if you add enough drag to the payload, you will then bring it down into a range where your current 5ft parachute would be usable
[12:05] <edmoore> you would have to have the parachute a long way behind the main payload, so it is clear of the aerodynmic effects that this flat plate will produce
[12:05] <edmoore> otherwise the parachute will be less effective.
[12:05] <edmoore> before I look into this - would putting a flat plate on be an option?
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[12:06] <edmoore> if you cover it in gold blanket, it would make it really easy to spot, and if you put the gps antenna on the top, it would be really well isolated from the interference of the radio on the bottom
[12:06] <edmoore> assuming you connect the blanket to 0V
[12:08] <gerard_mp> yes the flat plate would be good
[12:08] <gerard_mp> do u mean a flat plate between the cords right?
[12:09] <edmoore> well, no just a large flat plate bolted onto the top of the payload
[12:09] <edmoore> http://flickr.com/photos/meteotek08/2672451600/
[12:09] <gerard_mp> over the gps antenna?
[12:10] <edmoore> so cut a circle of perhaps 1M diameter (I will work out exactly hat diameter in a second) and bolt it down onto the top
[12:10] <edmoore> you could have to put the gps antenna on top of this plate
[12:10] <edmoore> or actually you could just cut an opening in the middle of the plate
[12:10] <edmoore> that bit doesn't matter as it would be in the air flow
[12:11] <edmoore> i just wonder if you were planning on pointing your camera up?
[12:11] <edmoore> it might get in the way of that
[12:11] <edmoore> cut holes for the chords too, obviosuly
[12:11] <gerard_mp> but the wind will break the plate or not?
[12:11] <gerard_mp> hmm well yes... but if we need to put it...
[12:11] <edmoore> you would have to re-inforce it
[12:12] <edmoore> some carbon fibre rods from a model shop, maybe
[12:12] <edmoore> of some string from the edges down to the bottom of the payload
[12:12] <edmoore> or*
[12:12] <edmoore> that would provide a good way to secure it too
[12:12] <gerard_mp> which material should be the plate?
[12:13] <edmoore> I would say perhaps some of the blue polystyrene you have used
[12:13] <edmoore> or actually, if you can get some ripstop nylon, use that
[12:13] <edmoore> and make a web with some carbon fibre bars
[12:13] <edmoore> it doesn't actually need to be carbon fibre
[12:15] <gerard_mp> what about making little parachutes around the payload? attached to the structure
[12:15] <edmoore> same principle, though I think this would have less chance of tangling.
[12:16] <edmoore> double check with rcoketman to see if they could express ship a bigger one to you
[12:16] <edmoore> I sent something from here (oxford) to rome last week. I sent it at 5pm UK times and it arrived at 10am Rome time.
[12:16] <edmoore> overnight.
[12:17] <gerard_mp> well I have to go right now
[12:17] <gerard_mp> I'll be here later
[12:17] <gerard_mp> thanks!!
[12:17] <edmoore> ok. i'll be around all day
[12:18] <gerard_mp> ok
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[12:18] <jcoxon> slow day in the office?
[12:20] <edmoore> youbetcha
[12:20] <edmoore> running some provisional sims before we set the cluster off running monteCarlos for about a months and a half.
[12:20] <edmoore> so it's a bit stop and start
[12:20] <edmoore> just going to stick lunch in microwave
[12:20] <edmoore> brb
[12:28] <kc0wys> hey everyone
[12:29] <kc0wys> i keep missing everone because i forget that mirc is minimized :|
[12:29] <jcoxon> hey kc0wys
[12:29] <jcoxon> long time...
[12:29] <kc0wys> ya
[12:29] <kc0wys> can't stay long, but i have made some progress
[12:30] <kc0wys> gps, adc, and on screen display code all works
[12:30] <kc0wys> kc0wys.com/projects/ensure/2
[12:31] <jcoxon> wow kc0wys thats sooo good
[12:31] <jcoxon> love the pelican case - a bit heavy but so cool
[12:32] <edmoore> back
[12:33] <kc0wys> thx, yea weight is a slight issue, but it should be below 6 lbs when i'm done -- ensure 1 was 8 lbs
[12:33] <edmoore> kc0wys: lovely job. got a launch date?
[12:33] <kc0wys> i keep setting launch dates and missing them
[12:33] <kc0wys> so launch date is asap :)
[12:34] <edmoore> lol
[12:34] <jcoxon> edmoore, its really interesting to see how we've gone small
[12:34] <jcoxon> and the rest of the world has gone big
[12:35] <kc0wys> in terms of balloons?
[12:35] <edmoore> jcoxon: in my shed there is a balloon that can take 100kg to 28km
[12:35] <jcoxon> and we have cheap payloads while others spend more time
[12:35] <jcoxon> nah not balloons - payloads
[12:35] <edmoore> and I have been on the phone with morning organising a drop test of 1000kg from 35km :p
[12:35] <jcoxon> yeah yeah - you're so cool in your mars lander teams blah
[12:35] <jcoxon> hehe
[12:35] <edmoore> but yes, for our personal stuff, we are going small
[12:36] <edmoore> well, minimal anyway. but then the flights have just been testing stuff really.
[12:36] <kc0wys> jcoxon: it's the second-system affect
[12:36] <kc0wys> http://en.wikipedia.org/wiki/Second-system_effect
[12:37] <jcoxon> hehe
[12:37] <kc0wys> well i g2g
[12:37] <jcoxon> i think a lot is to do with our strict radio rules - so we use small radios and also the risk of the sea so our payloads are cheap
[12:37] <kc0wys> this is true
[12:38] <edmoore> badger1.2 is getting SSE
[12:38] <edmoore> fergus has talked me about of it, thankfully
[12:38] <kc0wys> oh boy, time has flown, i've gotta go, cya all and good luck :)
[12:39] <jcoxon> cya
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[12:40] <jcoxon> bbiab got to pack my car
[12:40] <edmoore> ok
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[13:21] <edmoore> hi jcoxon
[13:24] <jcoxon> hey edmoore
[13:25] <edmoore> how's it going?
[13:28] <jcoxon> not bad
[13:28] <jcoxon> just packing before going home
[13:29] <edmoore> I might go home this evening too.
[13:29] <edmoore> Sis is dissappearing to spain on Sunday
[13:29] <edmoore> spose i should say goodbye
[13:29] <jcoxon> hehe, might be an idea
[13:30] <edmoore> And I want to build my dual deploy chute, more importanly!
[13:30] <jcoxon> haha
[13:30] <edmoore> hopefully going to fly it next nova
[13:30] <jcoxon> i've got to do some bad ass revision
[13:30] <jcoxon> so weds will be badger
[13:30] <edmoore> got something which i think is quite simple and robust now. I hope.
[13:30] <edmoore> provisionally
[13:30] <edmoore> I don't think I can make it, which is pooey
[13:30] <jcoxon> tis a shame
[13:31] <jcoxon> i think i might miss it as well
[13:33] <jcoxon> going to finish my wireless cutdowns this weekend
[13:35] <edmoore> cool
[13:35] <edmoore> I think ferg and i will be designing ours
[13:35] <edmoore> and get a batch made
[13:35] <jcoxon> wireless?
[13:35] <edmoore> nope
[13:35] <edmoore> wired
[13:35] <jcoxon> okay
[13:36] <jcoxon> oooo there are new royal geographic soc grants out
[13:50] <jcoxon> right i'm off
[13:50] <jcoxon> cya
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[18:55] <kurtfz> hello
[18:55] <kurtfz> :)
[19:04] <kurtfz> how can I connect to the GM862 module from Telit using gumstix?
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[19:26] <natrium42> sure, why not
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[19:35] <edmoore> should be no problem, kurtfz
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[19:56] <jcoxon> evening all
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[20:00] <jcoxon> wow everyone is returning
[20:01] <icez> yeah :P
[20:01] <jcoxon> cause of the mailing list email? :-)
[20:01] <icez> uhm
[20:02] <icez> there's a mailing list?:S
[20:02] <jcoxon> guess not!
[20:02] <jcoxon> its now a google group
[20:02] <icez> I really should clean up my email.
[20:02] <icez> I have too many mailinglists I don't read
[20:03] <jcoxon> fair enough
[20:03] <icez> so I have 1095 new emails
[20:03] <jcoxon> haha
[20:03] <jcoxon> so hows things icez
[20:03] <jcoxon> ?
[20:03] <icez> I gotta clean that up
[20:03] <icez> oh busy with school, transfering to university from college in a couple months
[20:04] <jcoxon> know the feeling
[20:04] <icez> you?
[20:05] <jcoxon> finished teaching for hte year today
[20:05] <jcoxon> got exams next week
[20:06] <icez> cool
[20:06] <icez> and not so cool:P
[20:06] <jcoxon> yeah
[20:07] <jcoxon> but once they are done i get some holiday for some ballooning
[20:11] <icez> cool
[20:12] <icez> I wanna get back to programming stuff
[20:12] <icez> I need to catch up with all the new stuff
[20:12] <jcoxon> :-)
[20:12] <icez> then maybe join a project when I feel comfortable enough not to mess everything up
[20:12] <jcoxon> hehe
[20:18] <edmoore> yo
[20:18] <jcoxon> hey edmoore
[20:18] <edmoore> all well?
[20:18] <jcoxon> yup, finally home
[20:19] <edmoore> cool
[20:19] <edmoore> I might head gome in a bit
[20:19] <edmoore> or tomorrow morning
[20:19] <edmoore> tough choice
[20:19] <jcoxon> oooo tough
[20:19] <edmoore> might have a slice of toast and a red bull and hit the road
[20:19] <edmoore> m25 should be clear by now
[20:20] <jcoxon> good luck!
[20:39] <edmoore> jcoxon: you're a medic, you know about plastic surgery. Google Jocelyn Wildenstein. I can't quite put a finger on it, but I reckon she's had something done. Corner of her eyes or something, just looks... well tell me what you think - am I on to something?
[20:39] <kurtfz> jcoxon, chatted with you previously one time about interfacing gm862 and gpsstix
[20:40] <jcoxon> edmoore, i think she has!
[20:40] <jcoxon> hey kurtfz
[20:40] <jcoxon> yeah i remember
[20:40] <kurtfz> I have currently tried connecting RXD, TXD, VCC, GND to GM862 evaluation board (RX-0, TX-I, 3.8V, GND)
[20:40] <edmoore> botox?
[20:40] <kurtfz> the HWUART
[20:40] <kurtfz> tried using kermit -l /dev/ttyS1 to breathe life into gm862
[20:40] <jcoxon> kurtfz, okay, but
[20:40] <kurtfz> but no reply back when sending AT
[20:41] <jcoxon> hmmmm
[20:41] <kurtfz> the voltage on the evaluation board is ~3.28V relative to GND
[20:41] <jcoxon> does txd go to txd and rxdt o rxd?
[20:41] <kurtfz> there are 4 holes marked at the HWUART
[20:41] <kurtfz> on the gpsstix
[20:41] <jcoxon> yu
[20:41] <jcoxon> p
[20:42] <kurtfz> I clipped on on VCC to 3.8V
[20:42] <kurtfz> GND to GND
[20:42] <kurtfz> RXD to RX-0
[20:42] <kurtfz> TXD to TX-I
[20:42] <kurtfz> that should be it right?
[20:42] <jcoxon> have you tried rxd to txd and txd to rxd
[20:42] <natrium42> shouldn't it be the other way around?
[20:43] <kurtfz> nope
[20:43] <kurtfz> should I?
[20:43] <jcoxon> yeah
[20:43] <kurtfz> no risk of frying anything then?
[20:43] <jcoxon> if you think about it, the txd (transmit) should go to a rxd (recieve) line
[20:43] <natrium42> wait, RX-0 means RX output from data set
[20:44] <natrium42> right?
[20:44] <natrium42> so it seems correct to connect it to RXD
[20:44] <jcoxon> (i've written it down as rx to tx and tx to rx
[20:44] <jcoxon> )
[20:44] <kurtfz> ok, I'll try
[20:44] <jcoxon> but it does ring some bells that its not the normal way
[20:45] <kurtfz> which program is suited to send and receive AT keywords?
[20:45] <jcoxon> there potential is another reason why its not working - i seem to remember that you need to check the GPIOs to get HWUART working, one sec i'll check
[20:45] <jcoxon> kermit would be best
[20:45] <kurtfz> k
[20:46] <jcoxon> on a side note i've found an interesting book http://www.amazon.com/Floating-Space-Airship-Program-Apogee/dp/1894959736
[20:47] <jcoxon> just got it - its basically about hte first few years of JP Aerospace
[20:48] <kurtfz> what's the connection with GPIO and UARTS?
[20:48] <kurtfz> don't really get that part
[20:48] <jcoxon> on my wiki?
[20:48] <jcoxon> oh sorry on the gumstix
[20:48] <jcoxon> basically the processor has a limited set of 'lines' yet has more functions
[20:49] <jcoxon> so you can change the functions of some of the lines, either from GPIOs to UARTS for example (this is only on selected lines)
[20:49] <jcoxon> kurtfz, are you using a verdex or a connex?
[20:50] <kurtfz> I'm using the Verdex XL6P
[20:51] <kurtfz> sandwiched between gpsstix and netSD :)
[20:51] <jcoxon> okay
[20:51] <jcoxon> here are the things we want to test
[20:51] <jcoxon> first
[20:51] <jcoxon> lets see if the serial port is actually working
[20:52] <jcoxon> the best way to do this is a loop back, so briefly (don't solder it!) connect the gumstix HWUART txd to rxd
[20:52] <jcoxon> when you open kermit and type you'll see it appear if the serial port is working
[20:53] <kurtfz> ok, shall try
[20:53] <kurtfz> I have started soldering
[20:53] <edmoore> http://www.break.com/index/it-guy-vs-dumb-employees.html giggling gently
[20:53] <kurtfz> using the IC clip wires they had at sparkfun.com
[20:54] <jcoxon> this is only a test so don't connect rxd to txd permentantly
[20:54] <jcoxon> (thats what i meant)
[20:55] <kurtfz> kermit -l /dev/ttyS1 and then connect right?
[20:56] <jcoxon> also do 'set carrier-watch off'
[20:56] <jcoxon> and 'set speed 115200'
[20:57] <kurtfz> hm, the screen just freezed
[20:57] <jcoxon> arrrghhh
[20:58] <jcoxon> try again :-)
[20:59] <kurtfz> I just type something and press Enter?
[20:59] <jcoxon> just typing should work
[20:59] <kurtfz> the cursor resets to the beginning of the line
[21:00] <kurtfz> that's normal?
[21:00] <jcoxon> do you see text as you type?
[21:00] <kurtfz> yes
[21:00] <jcoxon> now disconnect the link between rx and tx
[21:00] <kurtfz> aaah ;)
[21:01] <jcoxon> does the text continue to appear when you type?
[21:01] <kurtfz> nei
[21:01] <jcoxon> so the serial port works :-)
[21:01] <jcoxon> that makes me happy
[21:01] <jcoxon> right so its not hte gumstix
[21:01] <kurtfz> when sending an AT command from kermit
[21:01] <jcoxon> next attach tx to rx and rx to tx between the gumstix and gm862
[21:01] <kurtfz> I just write AT something and push Enter?
[21:02] <jcoxon> yeah
[21:02] <jcoxon> it'll respond OK
[21:02] <kurtfz> how do I escape from kermit
[21:03] <jcoxon> ctrl \ C
[21:03] <kurtfz> all in once or sequentially?
[21:03] <kurtfz> nothing happens
[21:04] <jcoxon> i do ctrl and \ together
[21:04] <jcoxon> then c
[21:04] <kurtfz> nothing
[21:04] Action: kurtfz closes putty
[21:05] <jcoxon> oh
[21:05] <kurtfz> ok, new kermit
[21:05] <jcoxon> so connect up the gm862 and gumstix
[21:05] <kurtfz> no response
[21:06] <jcoxon> hows it connect?
[21:06] <kurtfz> at the terminal
[21:06] <kurtfz> TXD to RX-0
[21:06] <kurtfz> RXD to TX-I
[21:06] <jcoxon> GND to GND?
[21:06] <kurtfz> sure
[21:07] <jcoxon> and then a seperate power supply
[21:07] <kurtfz> vcc is from gumstix
[21:07] <kurtfz> vcc to 3.8V
[21:07] <jcoxon> hmmmm, no don't do that
[21:07] <jcoxon> gm862 needs it own power supply
[21:07] <kurtfz> I mentioned that above
[21:07] <jcoxon> oh
[21:08] <jcoxon> the gumstix vcc shouldn't be connected to anything
[21:08] <kurtfz> what's the reason it's there?
[21:08] <jcoxon> well the gm862 requires 3.8v and up to 2A
[21:08] <jcoxon> the gumstix vcc provides 3.3v and nothing like 2As
[21:09] <kurtfz> 2A would drain a battery
[21:09] <kurtfz> depending on the battery of course :)
[21:10] <jcoxon> its not all teh time
[21:10] <jcoxon> but momentarily the gm862 can draw 2A
[21:10] <kurtfz> where do I get an approximate 3.8V , 2A++ power supply ?
[21:11] <jcoxon> a single 3.7v lipo battery
[21:11] <jcoxon> perfect
[21:11] <jcoxon> the gm862 is basically made for those lipo batteries
[21:11] <kurtfz> 3.7v verses 3.8v ?
[21:11] <kurtfz> versus
[21:11] <jcoxon> don't worry about that
[21:12] <jcoxon> its in the gn862 manual
[21:15] <kurtfz> I am looking up the batteries (also a temporary power adapter would be nice)
[21:15] <kurtfz> most of them have copper contacts (3) and no wires
[21:15] <jcoxon> they sell them on sparkfun
[21:15] <jcoxon> i'll find hte link
[21:16] <kurtfz> k
[21:16] <jcoxon> http://www.sparkfun.com/commerce/product_info.php?products_id=340
[21:17] <kurtfz> "This is the highest energy density currently in production" <-- currently could be interpreted as current in a hurry ;)
[21:18] <jcoxon> yeah
[21:19] <kurtfz> using any particular charger for this one?
[21:19] <jcoxon> a LiPo charger
[21:19] <jcoxon> i don't thnk it matters but again sparkfun does a good one
[21:20] <kurtfz> always wondered about 2000mAh and mAh unit
[21:20] <kurtfz> it's nothing but coulombs rights?
[21:20] <jcoxon> so it'll do 2000mA for an hour
[21:21] <kurtfz> just a number for the total amount of charge delivered per hour
[21:21] <kurtfz> you were content with the capacity it delivered during a balloon flight?
[21:22] <jcoxon> yup
[21:22] <jcoxon> the gm862 only draws 100mA or so normally
[21:22] <jcoxon> it just spikes at 2As occasioanlly
[21:22] <jcoxon> so the gumstix won't be able to take that
[21:23] <kurtfz> gm862 goes automatically in sleep mode when not requesting jobs using AT commands?
[21:23] <jcoxon> nah it just waits
[21:23] <jcoxon> i reckon the gm862 isn't powering up properly as you are only providing 3.3v
[21:23] <jcoxon> it really wants 3.8v
[21:24] <kurtfz> you had it running throughout the whole flight and only SMSing when below some altitude?
[21:24] <jcoxon> yup
[21:25] <kurtfz> I gotta get a battery soon and come back and ask you guys
[21:25] <kurtfz> later
[21:25] <jcoxon> hope that helps :-)
[21:25] <kurtfz> kinda regret not ordering the battery with this shipment
[21:25] <kurtfz> thanks, bbl
[21:26] <jcoxon> no problem
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[21:26] <kurtfz> one more thing
[21:26] <jcoxon> sure
[21:26] <kurtfz> should I connect GND from gumstix to GND on gm862?
[21:27] <jcoxon> yes, you need to complete teh circuit
[21:27] <kurtfz> is that necessary with the battery and all
[21:27] <jcoxon> yeah
[21:27] <kurtfz> the minus lead of the battery goes also onto GND?
[21:27] <jcoxon> yup, common ground
[21:27] <kurtfz> I see there are 2 GND holes on the evaluation board
[21:28] <jcoxon> which eval board do you have?
[21:28] <jcoxon> the breakout one
[21:28] <jcoxon> ?
[21:28] <kurtfz> yeah
[21:28] <jcoxon> okay cool
[21:28] <kurtfz> ditched the rs232 and usb version since I have serial capability using gumstix
[21:28] <jcoxon> fair enough
[21:29] <kurtfz> not sure if that was wise of me :)
[21:29] <kurtfz> ok, bbl
[21:29] <jcoxon> it'll be fine - once it works
[21:29] <jcoxon> cya
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[00:00] --- Sat Jul 19 2008