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[00:39] <Laurenceb> http://www.farmhousecheesemakers.com/news/all/west_country_farmhouse_cheesemakersr_plea_to_the_public_as_cheese_is_lost_in_space_24/
[00:41] <Laurenceb> they obviously did it wrong
[00:41] <Laurenceb> need to know about us :P
[00:43] <SpeedEvil> edmoore's been talking to them in some way I think
[00:45] <Laurenceb> I thought as much
[00:46] <Laurenceb> he likes mad projects :P
[00:46] <Laurenceb> http://www.pulseeng.com/index.php?950 <- looks good for data downlink from a rocket
[00:46] Nick change: KingJ -> kingj
[00:48] <Laurenceb> I think two stage 5Kg glow with a 20 gram payload will work
[00:48] <Laurenceb> a bit simpler than my previous design
[00:48] <SpeedEvil> :)
[00:48] <Laurenceb> http://pro38.com/products/pro98/motor/MotorData.php?prodid=7400M520-P
[00:49] <Laurenceb> one of those for the first stage - ~£450 in the UK
[00:49] <Laurenceb> it ends up getting a bit more delta v for the first stage #3Km/s
[00:50] <Laurenceb> not sure how that translates to re entery heating - I think heating duration is maybe more important
[00:52] <SpeedEvil> That depends on your sectional density only somewhat
[00:52] <SpeedEvil> more on your trajectory
[00:54] <Laurenceb> the good thing bout getting more delta v in the first stage is you need less overall delta v
[00:54] <SpeedEvil> yeah
[00:54] <Laurenceb> with the two stage spun solid tube launched from the first stage you need about 2Km/s for the first
[00:54] <SpeedEvil> Or more payload
[00:55] <Laurenceb> if you increase that to 3, the spun solid needs about 2km/s less
[00:55] <Laurenceb> pythagoras :P
[00:55] Action: SpeedEvil wants a c^2 drive.
[00:57] <Laurenceb> http://pro38.com/products/pro75/motor/MotorData.php?prodid=2486K510-P <- for the second stage maybe
[00:57] <Laurenceb> the accel is rather high
[00:58] <Laurenceb> several hundered G
[00:59] <SpeedEvil> The engine canna'e take it!
[00:59] <Laurenceb> a small SMD crystals should survive
[00:59] <Laurenceb> dunno...
[00:59] <SpeedEvil> yes - the electronics aren't really a problem
[00:59] <Laurenceb> you might have to go two stage to reduce the peak accel maybe :-/
[01:00] <Laurenceb> oh well I'm off, cya
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[07:58] <rjharrison> Morning jcoxon
[08:00] <jcoxon> morning
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[08:24] <rjharrison> Hi edmoore, Thanks for the Zusebit cheese update
[08:26] <edmoore> np
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[09:37] <jcoxon> morning RocketBoy
[09:41] <RocketBoy> hiya - how's it going
[09:42] <RocketBoy> just sent an email - I may launch tomorrow AM
[09:42] <jcoxon> oh cool
[09:42] <RocketBoy> depending on a number of things
[09:43] <jcoxon> fair enough
[09:43] <jcoxon> i probably won't be around
[09:43] <RocketBoy> np
[09:43] <jcoxon> good oppurtunity to get the listening network up and running again though
[09:44] <RocketBoy> yeah
[09:45] <jcoxon> we still need to fix your error
[09:45] <jcoxon> going to upgrade dl-fldigi to the latest version of fldigi
[09:45] <jcoxon> and make it more 'upgradeable' so watch this space :-)
[09:54] Nick change: kingj -> KingJ
[09:56] <jcoxon> bbl
[09:59] Nick change: KingJ -> kingj
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[15:47] <edmoore> jcoxon, natrium42 it was a SPOT gps on the cheese
[15:50] <DanielRichman> They're expensive... satellite trackers, right?
[15:55] <SpeedEvil> yes
[15:55] <SpeedEvil> they're remarkably cheap
[15:56] <SpeedEvil> 100 quid ish
[15:56] <SpeedEvil> well - cheap compared to the historical price.
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[15:59] <jcoxon> edmoore, ooo that makes more sense
[15:59] <jcoxon> clever idea
[15:59] <jcoxon> but without some hacking they aren't great for balloons
[15:59] <edmoore> yeah
[16:00] <jcoxon> also i think SPOT might start to cotton on soon :-p
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[16:13] <DanielRichman> woohoo! sd card code is working again
[16:14] <jcoxon> hehe
[16:14] <jcoxon> we should chart the ups and downs of your SD card code
[16:15] <DanielRichman> It's pretty wobbly
[16:15] <jcoxon> oh, i'm sure you'll stabalise it
[16:16] <DanielRichman> Very nearly there. The blocks of 128bytes was a bad idea and the SD card behaved strangly
[16:16] <DanielRichman> I've got it working now, just for some reason it's not writing more than 3 kb and infinite looping... probably a typo somewhere
[16:21] <DanielRichman> holy-- add the apex to the chart, tis realleh working now!
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[16:24] <DanielRichman> It appears to have successfully written about 4mb of Hello world... success!
[16:34] <SpeedEvil> meh
[16:34] <SpeedEvil> You mean 128 bytes ddon't or do work?
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[16:42] <DanielRichman> Doesn't appear to
[16:42] <DanielRichman> was behaving very strangely
[16:42] <DanielRichman> Maybe I got it totally wrong, but got bored of wrestling with 128byte blocks
[16:43] <DanielRichman> the new method is better anyway, instead of a message-per-block it just continuously writes
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[16:43] <SpeedEvil> :/
[16:44] <edmoore> hi jcoxon
[16:47] <jcoxon> hey edmoore
[16:47] <jcoxon> got it compiled
[16:47] <jcoxon> just working out how to get it to run
[16:47] <jcoxon> :-p
[16:49] <edmoore> it's easy
[16:49] <edmoore> you only need about 37 command line arguments
[16:49] <edmoore> and exactly the right format of grib
[16:49] <edmoore> piece of piss
[16:49] <jcoxon> hehe
[16:50] <jcoxon> having issue with the valid_model_run
[16:52] <jcoxon> 2 numbers - recognised the first as date and time
[16:52] <jcoxon> but then second doesn't make any sense to me
[16:52] <jcoxon> http://www.srcf.ucam.org/~cuspaceflight/websvn/filedetails.php?repname=CUSF&path=%2Flanding_prediction%2Fwebsite+prediction%2Fvalid_model_run.txt
[16:53] <edmoore> i think it might be something to do with the box grid, but i don't know. fergus wrote the php front end to it
[16:53] <edmoore> rob who wrote it is on holiday
[16:53] <jcoxon> fair enough
[16:54] <jcoxon> the code should tell me really
[16:54] <jcoxon> i'll have a work through
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[16:56] <jcoxon> but of course - unix time
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[17:03] <jcoxon> edmoore, twas unix time
[17:03] <edmoore> you said the first one was unix time?
[17:03] <edmoore> oh, i just looked at the file
[17:03] <edmoore> yes, the whole thing runs on unix time
[17:04] <edmoore> which is why there are all sorts of confusing things
[17:04] <edmoore> also why it ignores BST but also projects an hour ahead when you log onto the predictore, fooling you into thinking it is on BST when infact it is on GMT but has just made the defualt now+1hr
[17:05] <jcoxon> hehe
[17:18] <jcoxon> edmoore, woohoo
[17:18] <jcoxon> got it working
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[19:35] <jcoxon> hey RocketBoy rjharrison
[19:37] <RocketBoy> yoyo
[19:38] <RocketBoy> the flight tomorrow is off - one of the ducks didn't line up
[19:39] <jcoxon> oh well
[19:39] <jcoxon> postponed till?
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[19:39] <RocketBoy> next week
[19:40] <jcoxon> okay
[19:41] <RocketBoy> I think it will give me time to change the telemetry format to a generic XABEN
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[19:42] <jcoxon> okay cool
[19:42] <jcoxon> well dl-listening system is increasingly flexible
[19:47] <rjharrison> cool
[19:47] <rjharrison> but xaben is good
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[19:53] <RocketBoy> XABEN will use the NEMA style checksum as before
[19:53] <RocketBoy> NMEA even
[19:55] <RocketBoy> I'll do the changes tomorrow and post some wavs
[19:57] <rjharrison> cool
[19:59] <rjharrison> RocketBoy, jcoxon, natrium42 knocking up pressure sensor test
[19:59] <jcoxon> great
[20:03] <jcoxon> i've managed to fuse together cusf flight predict with hysplit
[20:03] <SpeedEvil> to do floaters?
[20:03] <jcoxon> yes!
[20:03] <SpeedEvil> neat
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[20:07] <jcoxon> jsut trying to convert the data files to kml
[20:07] <jcoxon> so it makes more sense
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[20:12] <RocketBoy> it would be nice to do variable ascent rates - I was thinking of using ballast to catch easterly ground winds by doing low AR then dump ballast just before hitting westerly JS
[20:27] <jcoxon> i'll see what i can do
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[21:55] <rjharrison> RocketBoy I was wondering where you got the coupling values from on the circuit
[21:55] <rjharrison> http://www.farnell.com/datasheets/9718.pdf
[21:55] <rjharrison> The suggested circuit has different values here
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[21:58] <SpeedEvil> the decoupling is almost irrelevant
[21:59] <SpeedEvil> It uses so little power that practically anything will work
[21:59] <SpeedEvil> what's rocketboys values?
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[22:00] <RocketBoy> the values are the same 0.01uF = 10nF
[22:01] <RocketBoy> just you wont find anyone selling you a 0.01uF cap - it will be called 10nF
[22:04] <rjharrison> It was the 470pf one really
[22:04] <rjharrison> is the 10nf a miss type
[22:06] <RocketBoy> the 470pf isn't de-coupling its high frequency cut off when the sensor is feeding a high impedance load
[22:07] <RocketBoy> but the circuit is now feeding the 51k ohm load of the potential divider (to provide the 3.3V interface)
[22:08] <RocketBoy> the 10nF and 18K/33K resistor potential divider combination gives a similar frequency roll off as the 470pF and sensor output impedance
[22:10] <RocketBoy> the sensors generate a lot of noise above about 500Hz - so the 18k/33k & 10Nf is intended to give roll off to attenuate above this
[22:17] <RocketBoy> acutally 22nF might be better
[22:22] <SpeedEvil> yeah.
[22:22] <SpeedEvil> Not as if you need fast response :)
[22:23] <RocketBoy> yeah
[22:23] <SpeedEvil> this goes into some sort of avr I assume?
[22:26] <RocketBoy> the application note talks about averaging over many samples (e.g. 64)
[22:31] <SpeedEvil> noise might be of use in that app actually
[22:31] <RocketBoy> ? randomization?
[22:34] <SpeedEvil> ADCs typically have poor linearity - if you look at the threshold voltages between - say - 34 and 35 - it may not be 1 unit away from the threshold between 35 and 36
[22:34] <SpeedEvil> Differential non-linearity
[22:37] <SpeedEvil> http://pdfserv.maxim-ic.com/en/an/AN641.pdf
[22:37] <SpeedEvil> is a good overview
[22:37] <SpeedEvil> if the gaussian noise from the sensor smears the output over several bins - it improves the averaging a bit.
[22:41] <RocketBoy> yep - agree
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[23:09] <RocketBoy> nights
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