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[11:39] <Laurenceb> hi jcoxon
[12:40] <Cooleo> http://euphoria-radio.com/blog/?p=3
[12:41] <Laurenceb> is that you?
[12:41] <Cooleo> Yeo
[12:41] <Cooleo> *Yep
[12:42] <Laurenceb> neat
[12:42] <Cooleo> :)
[12:42] <Laurenceb> I'd just go for a launch
[12:43] <Cooleo> Hehe :)
[12:43] <Cooleo> Well, It'd be up in Lowestoft Suffolk if you could get here.
[12:43] <Cooleo> (Its an Hour south of Norwich)
[12:43] <Laurenceb> I might have a parafoil ready some time soon
[12:44] <Laurenceb> after finals :-/
[12:44] <Cooleo> Cool.
[12:44] <Cooleo> What are you studying?
[12:44] <Laurenceb> physics
[12:44] <Cooleo> Nice. Guess that helps a fair bit
[12:45] <Laurenceb> are you a student?
[12:45] <Cooleo> Yeah
[12:46] <Laurenceb> what you studying?
[12:46] <Cooleo> Eurgh, Like everything. Final year of GCSE's
[12:47] <Laurenceb> oh
[12:47] <Cooleo> Haha, Wern't expecting that :)
[12:47] <Laurenceb> I see, thought you meant uni
[12:47] <Laurenceb> :P
[12:47] <Cooleo> Nope. Not for a couple of years yet
[12:47] <Laurenceb> luck :D
[12:47] <Laurenceb> *lucky
[12:47] <Cooleo> :P
[12:48] <Laurenceb> its hard work
[12:48] <Cooleo> Yeah, I would guess. What are you doing after you've finished?
[12:57] <Cooleo> Ill be right back, Need to reboot.
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[13:04] <Cooleo64> Back.
[13:08] <Laurenceb> hi
[13:09] <Laurenceb> well, hopefully I'll be doing a phd studentship at surrey satellite technology after I graduate... interview tomorrow
[13:11] <Cooleo64> Thats Cool!
[13:12] <Cooleo64> Good Luck.
[13:12] <Laurenceb> thanx
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[13:21] Nick change: Cooleo64 -> Cooleo
[13:42] <Cooleo> Hmm, 100M Test Launch looks good for second weekend in may
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[14:28] <jcoxon> afternoon all
[14:31] <Cooleo> Hey.
[14:32] <jcoxon> hey Cooleo
[14:32] <Laurenceb> jcoxon: what did you use to do the logo?
[14:32] <Laurenceb> its very good btw :D
[14:32] <jcoxon> i didn't
[14:32] <jcoxon> icez made it ages ago
[14:32] <Laurenceb> ah
[14:33] <jcoxon> i just had a copy
[14:33] <Laurenceb> cool
[14:33] <Laurenceb> what for is it in?
[14:33] <Laurenceb> *form
[14:33] <jcoxon> jpeg i think
[14:33] <jcoxon> it was on my external hard drive
[14:33] <Laurenceb> just wondering how we could redo the font
[14:33] <Laurenceb> maybe icez has the origional still
[14:34] <jcoxon> Laurenceb, haha, here is a question, what on linux are you using for your rtty decoding
[14:34] <Laurenceb> fldigi
[14:34] <jcoxon> yeah i've had a look out for him but he isn't around
[14:34] <jcoxon> (i've especially checked #space)
[14:34] <Laurenceb> right
[14:34] <jcoxon> Laurenceb, is it any good?
[14:34] <Laurenceb> seems to be
[14:34] <Laurenceb> I have this weird timing error
[14:35] <Laurenceb> but it appears to be my laptop, and fldigi can correct it
[14:35] <Laurenceb> rocketboy got my radio working on his winXP machine with truetty, so probably my soundcard IMO
[14:35] <Laurenceb> other than that its really good
[14:36] <jcoxon> hmmm okay
[14:36] <jcoxon> basically my laptop can't travel
[14:36] <jcoxon> it works but only cause i've had to fix it
[14:37] <jcoxon> and if it gets knocked it dies
[14:37] <Laurenceb> the developer is helpful as well, he gave me some tips on compiling it for AMD64
[14:37] <jcoxon> cool
[14:38] <jcoxon> so i was thinking of a replacement
[14:38] <Laurenceb> but I've not tried it with one of rocketboys radios
[14:38] <Laurenceb> it works with rtty wav files I downloaded and my radio design
[14:39] <Cooleo> Sorry to interupt, But whats the formula for the weight helium can lift?
[14:40] <Cooleo> Thanks
[14:41] <jcoxon> i think there is also a spreadsheet on the wiki
[14:41] <Laurenceb> jcoxon: planning on investing in a new laptop then?
[14:41] <jcoxon> well perhaps
[14:41] <jcoxon> i really really can't afford one
[14:41] <jcoxon> and this one works, just cuts out occasionally
[14:41] <jcoxon> but probably can manage as a desk laptop
[14:41] <Laurenceb> you can get an ok machine for £300
[14:42] <Laurenceb> but it wont be a mac :P
[14:42] <Cooleo> If you need a desktop, I can sell you a decent one, and you could put OSX on it
[14:44] <jcoxon> Cooleo, thanks, i've got a desktop
[14:44] <jcoxon> Laurenceb, i know
[14:44] <jcoxon> so i was thinking of a eeepc
[14:44] <jcoxon> its more for things like taking out to the launch
[14:44] <Cooleo> Ok, Np.
[14:45] <jcoxon> my ibook can carry on for a few more months
[14:45] <Cooleo> Which iBook do you have? I just got an G3 off ebay :)
[14:46] <jcoxon> i've got a g4 800mhz
[14:46] <jcoxon> had it for ages - this my perfect laptop
[14:46] <Cooleo> Cool :)
[14:46] <Cooleo> I took mine apart yesterday, Gotta fix a DC-IN cable and ripped the CD ribbon cable. Gah. :)
[14:48] <jcoxon> i also like the hackability of the eeepc
[14:48] <jcoxon> was going to stick a gps in it
[14:49] <Cooleo> You can also make them Touchscreen.
[14:50] <jcoxon> or...
[14:50] <jcoxon> a gumstix
[14:50] <jcoxon> inside
[14:51] <Cooleo> Nice
[14:51] <jcoxon> dual core :-p
[14:51] <Cooleo> Haha :)
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[15:07] <Cooleo> Hmm, 6 x 11" Helium balloons should be more than enough to lift 200 grams right?
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[15:29] <Cooleo> What is a good way to get a downlink straight to a PC? Ive cancelled out Bluetooth and WiFi because they can't get that far.
[15:29] <fnoble> hello
[15:30] <Cooleo> Hey.
[15:30] <fnoble> most people in the UK use the modules made by radiometrix
[15:30] <fnoble> google them
[15:30] <Cooleo> Cool Thanks.
[15:31] <fnoble> by law you can only transmit 10mW from an unmanned aerial vehicle
[15:31] <Cooleo> (Although, I do have a really small spare wireless router here with a ethernet port on it. Hmm)
[15:31] <Cooleo> Oh, Ok thanks
[15:32] <Cooleo> I found my FM transmitter, I might Mod that.
[15:32] <Laurenceb> you'll need some form of uC based board to act as a modem
[15:32] <Laurenceb> most of us use rocketboys modules
[15:33] <fnoble> yeah, might be a good idea to build a rocketboy module to start with
[15:33] <Cooleo> Cool, Thanks
[15:33] <jcoxon> rocketboy should makes some kits
[15:33] <jcoxon> they would be v. popular
[15:34] <fnoble> jcoxon: are the rocketboy schematics on the web?
[15:34] <Laurenceb> this is the sort of thing- http://wiki.ukhas.org.uk/_media/projects:dscn0979.jpg
[15:34] <Laurenceb> thats my own design, but uses the same principle
[15:34] <jcoxon> nope
[15:35] <fnoble> Lb: i was always meaning to ask, what do the pots on your board do? the blue ones
[15:35] <Laurenceb> control channel spacing and center voltage
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[15:35] <Laurenceb> on the v2 board design, theres only one pot, for channel seperation
[15:36] <fnoble> ah ok, do you do any shaping?
[15:36] <Laurenceb> yes
[15:36] <Laurenceb> 8 bit resolution
[15:36] <Laurenceb> 156 steps per bit
[15:36] <Laurenceb> ie per transmitted bit
[15:36] <fnoble> so the pots are just read by the AVR? or is there some kind of analogue front end
[15:37] <Laurenceb> theres an analogue front end
[15:37] <Laurenceb> I could email you a tarball of the whole project if you want
[15:38] <jcoxon> fnoble, i'm thinking for the launch next week to only get the flight computer to transmit the long and lat every 5 or so cycles and just transmit the altitude in between?
[15:39] <jcoxon> we never really pay any attention to its position until later on
[15:39] <Laurenceb> it doesnt work with the power saving enabled for some reason - its something I built in later to make the AVR hibernate when not transmitting
[15:40] <Laurenceb> the first byte is corrupted upon wakeup, and that will screw truetty badly, but fldigi doesnt mind too much
[15:40] <fnoble> hmm... i don't know
[15:40] <fnoble> if something goes wrong then its usefult to know which way it was starting to go
[15:40] <Laurenceb> jcoxon: using rtty?
[15:40] <fnoble> and with the counts output its going to be slow
[15:40] <jcoxon> Laurenceb, no, morse style
[15:41] Action: Laurenceb shakes his head
[15:41] <jcoxon> oi
[15:41] <Laurenceb> use rtty
[15:41] <jcoxon> not without another uC
[15:41] <jcoxon> and that defeats the object
[15:41] <Laurenceb> I'm sure rocketboy can lend you a radio
[15:41] <fnoble> Laurenceb: I might ask you for the tarball sometime, but for now it would just distract moe from work
[15:42] <Laurenceb> if not, I have one of his you can borrow :P
[15:42] <fnoble> jcoxon: im sure yo could do slow rtty from the gm862
[15:42] <Laurenceb> fnoble: I know the feeling XD
[15:42] <jcoxon> yeah but it would have no shifting
[15:42] <fnoble> do you have another spare serial port?
[15:42] <Laurenceb> I'm not actually sure how good the shifting is
[15:43] <jcoxon> well
[15:43] <Laurenceb> theoretically its not benficial
[15:43] <jcoxon> i have an Tx line spare
[15:43] <fnoble> the shifting?
[15:43] <Laurenceb> I'm struggling to understand the theory
[15:43] <Laurenceb> yes
[15:43] <Laurenceb> say you do an FFT of the incoming audio
[15:43] <Laurenceb> you want everything to end up in one frequency bin or another
[15:44] <fnoble> could fly a rocketboy radio too :)
[15:44] <Laurenceb> then compare the bins to get an output
[15:44] <jcoxon> nah its cool
[15:44] <jcoxon> i'm happy with the radio right now
[15:44] <fnoble> ok
[15:44] <jcoxon> i'm pretty good at decoding it
[15:44] <fnoble> FFT is a BAD way to decode FSK
[15:44] <jcoxon> fnoble, its a future upgrade
[15:44] <jcoxon> once this works :-p
[15:44] <fnoble> use the FFT to tune, but then MUCH better to use matched filters
[15:46] <fnoble> you can match the filter response to the output spectrum of the radio
[15:46] <fnoble> and then you minimise the amount of radio power you are wasting
[15:48] <fnoble> and i think in theory FSK is supposed to be better then OOK
[15:48] <Laurenceb> hmm
[15:48] <Laurenceb> FFT is the best in theory
[15:48] <fnoble> really?
[15:48] <Laurenceb> if you have an SSB scanner
[15:48] <Laurenceb> then audio
[15:49] <Laurenceb> your decoding digitally
[15:49] <fnoble> FFT smears the time resolution more than necessary
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[15:49] <Laurenceb> hmm
[15:49] <Laurenceb> yes, its best to be time synced
[15:49] <Laurenceb> ence my gps idea
[15:49] <Laurenceb> *hence
[15:49] <fnoble> because your FFT window is as long as the lowest frequency you want to measue
[15:50] <fnoble> which is going to be lower than the transmission frequency
[15:50] <Laurenceb> ideally your window is one bit long
[15:50] <Laurenceb> bbl
[15:50] <fnoble> also if your FFT window crosses a bit change then you get a load of harmonics
[15:50] <jcoxon> haha i didn't follow any of that
[15:51] <jcoxon> (don't worry i don't need to understand it)
[15:51] <fnoble> yeah radio theory is weird, had to try and learn some when i was working on that FEC stuff
[15:51] <fnoble> actually i need to revisit that sometime
[15:51] <jcoxon> tis black magic
[15:54] <fnoble> ok, time to get back to my physics report
[15:54] <fnoble> god damn gyroscopes
[15:54] <jcoxon> sounds fun
[15:55] <jcoxon> i'm revising how to do a endoscopy
[15:56] <fnoble> keep forgetting your doing medicine
[15:56] <fnoble> :)
[15:56] <jcoxon> i think its more 'pretending' to do medicine
[15:57] <jcoxon> i rarely do stuff, hehe
[16:04] <fnoble> what kind of medicine are you specializing in?
[16:05] <jcoxon> oh i'm still just doing general stuff
[16:05] <jcoxon> will be a few years before i need to decide if i want to specialise
[16:05] <jcoxon> not yet a doctor :-)
[16:05] <fnoble> i see
[16:06] <Tigga> fnoble: yuck, gyros
[16:06] <Tigga> they stink
[16:06] <Tigga> you just have to trust the equations and try not to think too hard :P
[16:07] <fnoble> yeah, and i have to write a full length report on some crappy experiment we did to test the formula for precession
[16:07] <fnoble> and try and make it sound like interesting science
[16:08] <fnoble> wanted to write for my abstract "checked precession formula - it works", but no, i have to spin it out to like 200 words
[16:11] <jcoxon> fnoble, we should get one of those usb mobile broadband sticks
[16:11] <jcoxon> so we can get forecasts and google maps out in the field
[16:12] <fnoble> yeah, can you get them without contract?
[16:12] <jcoxon> yeah
[16:12] <fnoble> like pay as you go or something
[16:12] <jcoxon> i've only seen contract
[16:12] <jcoxon> but i'll have a look
[16:13] <Cooleo> Ive got Google Maps on Three Mobile pay as you go and its free.
[16:13] <fnoble> yeah, maybe an internet phone would be good enough
[16:14] <jcoxon> well i have maps already on my phone
[16:14] <jcoxon> as its got gps and nav software
[16:14] <jcoxon> just found the 3 pay as you go mobile broadband
[16:14] <Cooleo> Hehe :). I picked up an old Motorola on eBay, that has a built in GPS :)
[16:15] <Cooleo> How much do they charger for the Mobile Dongle?
[16:15] <jcoxon> ?69.99
[16:16] <Cooleo> Rip off. You can buy the Three Skype Phone for £49.99 New which can connect up at a modem
[16:16] <Cooleo> on the three pay as you go mobile broadband package
[16:17] <Cooleo> *as a modem
[16:18] <jcoxon> hehe
[16:18] <jcoxon> i have a spare GM862 module
[16:18] <jcoxon> could use that if i could be arsed to wire it up
[16:18] <Cooleo> Hehe. :)
[16:18] <Cooleo> If not, You could grab a used mobile on eBay for about a tenner with a USB cable. And use that.
[16:18] <jcoxon> i'm less sure its actually worth the money
[16:19] <jcoxon> we end up getting wireless when we boogie back to churchill for brunch
[16:19] <fnoble> yeah, and can probably at least use a normal phone as a dialup modem
[16:19] <Cooleo> Yeah
[16:20] <Cooleo> You can buy the day if needs be. 50P a day
[16:21] <jcoxon> and if we pre-cache google earth
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[16:21] <Hiena> 'napot!
[16:22] <Hiena> Khm...Good afternoon!
[16:23] <jcoxon> hey Hiena
[16:23] <jcoxon> you been flying?
[16:25] <Hiena> Nope. I have a glider problem. I have to buy a new one, because my current glider getting a bit dangerous. It's a 14 years old Moyes GTR, and it's in a poor condition.
[16:26] <Hiena> The sail and the flying wires loose. And at the start acting "strange".
[16:26] <jcoxon> oh
[16:28] <Hiena> I had a spin-off at the winch start at the last weekend. I repaired the bent battens, but i'm not sure it will be flying again.
[16:29] <Hiena> Now, i'm looking for a new glider, but i really has no money to burn.
[16:30] <jcoxon> know the feeling
[16:33] <Cooleo> http://euphoria-radio.com/blog/?p=5
[16:34] <Laurenceb> fnoble: back
[16:34] <Laurenceb> I kind of see where your going...
[16:34] <Laurenceb> very odd, if you have 300 bps, so you make you fft window 1/300 seconds long, you need a 300hz seperation between 0 and 1
[16:35] <Laurenceb> but RTTY will work with a 150hz seperation
[16:35] <Hiena> Also i have a ticking "wanna go to fly" feelings too. The flying is the only thing what makes me endure my life. I need an adrenalin rush to survive the dull weekdays.
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[16:36] <jcoxon> :-)
[16:41] <Laurenceb> I think I've been thinking of OFDM... but I'm still not sure how RTTY functions with a seperation of half the bitrate
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[16:54] <Laurenceb> fnoble: I still dont think you can surpass FFT of one form or another for decoding
[16:55] <fnoble> matched filters are the usual method for fsk
[16:55] <Laurenceb> but the fact that RTTY works with as little as 150hz seperation is pretty odd... I dont get it
[16:56] <fnoble> also require less computational power
[16:56] <Laurenceb> yes, but thats due to the old school ham types who make it
[16:56] <fnoble> well, maybe they just accept a bit of harmonic noise
[16:56] <Laurenceb> I'm obviously missing something
[16:56] <Laurenceb> RTTY does work at <300Hz spacing, I've tried it myself
[16:58] <Laurenceb> I'm bidding on an RC parafoil :P unfortunately the seller seems to be bidding against me :-/
[16:58] <fnoble> i think you can have any separation, irrespective of the data rate
[16:58] <fnoble> just not if you use FFT
[16:58] <Laurenceb> shannon would suggest so
[16:59] <fnoble> dunno, im no expert
[17:00] <fnoble> but it seems that the disadvantage of the FFT is it works over a window
[17:00] <Laurenceb> http://en.wikipedia.org/wiki/Shannon_limit
[17:00] <fnoble> but a filter is continuous
[17:00] <Laurenceb> yes
[17:00] <Laurenceb> but syncronised FFT is a bit different
[17:01] <Laurenceb> you can also have multiple overlapping windows, but thats computationally nasty
[17:02] <Laurenceb> bbl
[17:02] <fnoble> i dont think the shannon limit is relavent here
[17:02] <fnoble> the channel capacity isnt the same as the frequency shift
[17:03] <fnoble> the limiting factor on separation is the radio output spectrum, you dont want the spectra of the mark and space to overlap
[17:04] <fnoble> (i think)
[17:04] <fnoble> and they can overlap, you just get more intersymbol interference
[17:17] <Cooleo> Huzzah, Rubbish Payload finished :D
[17:18] <jcoxon> that was quick
[17:19] <Cooleo> It contains a Camera and a Wifi Router :P
[17:19] <Cooleo> The router is mearly to test the serial downlink on it
[17:19] <Cooleo> and its made out of an ice cream tub :)
[17:20] <Cooleo> Just hoping someone buys my SkyBox on ebay so I can buy helium
[17:21] <jcoxon> how are you triggering the camera?
[17:21] <Cooleo> With my finger. Im making sure it starts recording before I start the flight test.
[17:22] <jcoxon> oh you are filming
[17:22] <Cooleo> Yep
[17:22] <Cooleo> Its a cheap chinese camera I got online, so I wouldn't know how to make it take pictures :P
[17:22] <jcoxon> and the wifi router is just doing wifi as a downlink?
[17:22] <Cooleo> Yes :)
[17:22] <Cooleo> I dont know what else I could really do with it
[17:22] <jcoxon> hehe
[17:22] <Cooleo> Its one of the free La Foneras.
[17:22] <jcoxon> i developed a whole payload based on a wifi router running linux
[17:22] <Cooleo> Hehe Cool.
[17:23] <jcoxon> pegasus IV
[17:23] <Cooleo> I think this one is running OpenWRT
[17:23] <Cooleo> nice. Ill look it up
[17:23] <jcoxon> never launched it as it had issues just before launch
[17:23] <Cooleo> Surely the signal would die after a certain point?
[17:23] <jcoxon> oh i wasn't going to use the wifi
[17:24] <jcoxon> you aren't actually allowed to use wifi in the air :-p
[17:24] <Cooleo> Oh right :P. I want to see them get it down
[17:24] <jcoxon> but they are cheap embedded linux boxes
[17:24] <jcoxon> with 2 serial ports
[17:24] <Cooleo> Cool.
[17:24] <Cooleo> I might look into it
[17:25] <fnoble> you know you could probably use a la fonera as the basis for a flight computer
[17:25] <Cooleo> Really?
[17:25] <Cooleo> :O
[17:25] <fnoble> yeah, they run linux dont they?
[17:25] <jcoxon> if its openwrt thats what i did
[17:25] <Cooleo> I think so, OpenWRT
[17:25] <Cooleo> Would need to flash it first though
[17:25] <jcoxon> added a gps and a phone
[17:26] <Cooleo> 16MB RAM, 8MB ROM, 153MHZ Prosseccor
[17:26] <jcoxon> used a python script in between and gnokii to communicate with teh phone
[17:26] <Cooleo> Didn't the phone cut out?
[17:26] <jcoxon> check out peg IV
[17:26] <jcoxon> Cooleo, oh yes
[17:26] <jcoxon> but it works great when you land
[17:26] <Cooleo> Ahh :)
[17:26] <Cooleo> Ahh Cool, Found it on the Wiki.
[17:27] <fnoble> yeah, if you can work out how to write software for the la fonera, it should have some free serial ports
[17:27] <fnoble> to add the gps to
[17:27] <Cooleo> People have already unlocked the serial port on it
[17:28] <Cooleo> http://www.dd-wrt.com/wiki/index.php/LaFonera_Hardware_Serial-Cable-Port
[17:28] <fnoble> awesome
[17:28] <fnoble> dont use the wifi bit though, just think of it as a cheap, mobile linux computer
[17:28] <Cooleo> Cool :D
[17:29] <fnoble> the wifi will get you into trouble :) (or most likely just not work at all)
[17:29] <Cooleo> Ill have to fix it up again. I turned it into a flapjack cooker for abit.
[17:29] <fnoble> !!? flapjack cooker
[17:29] <Cooleo> Yes
[17:29] <fnoble> it runs that hot?
[17:30] <Cooleo> The thing heats up alot. So I made it into a flapjack cooker! I got the plastic from a 9V battery box, Added Butter, Sugar, and Syrup. Cooked it for 10 minutes, then added oats, mixed it and cooked it for an hour
[17:34] <fnoble> heh
[17:34] <Cooleo> Hmm. You can power the La Fonera via USB which could be quite handy.
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[17:34] <Cooleo> I could make a USB battery pack and power it that way
[17:34] <fnoble> looks like people have added SD card interfaces for it too for logging the data to
[17:34] <fnoble> also seen an I2C interface
[17:34] <Cooleo> Yep. People even made it into a shoutcast server :P
[17:35] <fnoble> I2C is useful as lots of sensors can be interfaced via i2c
[17:35] <Cooleo> Hmm, Cool.
[17:35] <fnoble> like temperature probes, accelerometers etc.
[17:35] <fnoble> and you can add up to 256 devices on one i2c interface
[17:36] <Cooleo> Sweet
[17:36] <Cooleo> Battery life would be bad though, Right?
[17:36] <fnoble> looks like it is a bit short of i/o pins, but if you did the i2c mod you could use an i2c GPIO expander
[17:37] <fnoble> basically a chip that connects to the i2c bus and gives you a bunch of input and output pins you can control
[17:37] <Cooleo> Hmm Cool.
[17:37] <Cooleo> the I2C thing looks like it needs a PCB to make it work.
[17:39] <fnoble> looks like its done on perfboard
[17:39] <Cooleo> and man it looks confusing to wire that Serial port to it
[17:39] <fnoble> all part of the fun, figuring things like this out :)
[17:40] <Cooleo> Yep
[17:41] <Laurenceb> back
[17:41] <Laurenceb> fnoble: think I get it
[17:41] <Laurenceb> I was thinking it had to be orthogonal
[17:42] <Laurenceb> but thats no the case, the technique I was thinking of with FFT window=bit lenght is binary orthogonal frequency modulation
[17:43] <Laurenceb> so there is no "crosstalk" between 0 and 1
[17:43] <Laurenceb> the datalink will still work if that isnt the case, but I still dont see how the shaping helps...
[17:47] <fnoble> shaping stops you wasting radio power in other parts of the spectrum
[17:47] <fnoble> and stops other radio users getting pissed off
[17:48] <fnoble> because otherwise you create a big load of broadband noise on every transition
[17:49] <fnoble> try it, send some data with no shaping and you will hear clicks even if your radio is tuned really far off from where you are transmitting
[17:56] <fnoble> anyone know of good software for making scientific diagrams on mac os x?
[18:11] <Cooleo> Hmm, So the La Fonera looks a good choice for a small linux PC.
[18:19] <Cooleo> Would old Li-On mobile phone batterys be alright for power? or would they not work under the pressure?
[18:28] <Laurenceb> fnoble: sure, but for actual range I dont see the benfit
[18:28] <fnoble> yeah, smoothing my not help range
[18:28] <Laurenceb> Cooleo: it might well work
[18:29] <fnoble> although i think it may affect an FFT based decoder
[18:29] <Laurenceb> yes
[18:29] <Laurenceb> that was my point orgigionally, FFT decoders work best without shaping
[18:29] <fnoble> no, i was thinking FFT would be screwed by the noise without shaping
[18:30] <Laurenceb> Cooleo: but li-poly and li-ion dont function as well at low temperature as the single use ones
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[18:30] <fnoble> because it takes a wide chunk of spectrum
[18:30] <Laurenceb> the noise would be in other frequency bins
[18:30] <Laurenceb> and hence ignored
[18:30] <Laurenceb> single use ones= single use lithium
[18:30] <fnoble> mmm, i guess so, i mean some noise would get into the bin of other frequency
[18:30] <fnoble> but thats true of filters also
[18:31] <Laurenceb> yes, but a windowing function would take care of that
[18:31] <Laurenceb> and because the noise is so spread out, its a small effect
[18:31] <Laurenceb> unless your another radio user :P
[18:31] <fnoble> although with the FFT if the window was out it would add noise to a whole sample ,but a filter it would be less siginificant because its constantly refreshing
[18:32] <Laurenceb> yes, I think syncronised FFT windows would help a lot
[18:32] <fnoble> i mean whole bit rather than whole sample
[18:32] <Laurenceb> I undertsand you
[18:32] <fnoble> yeah, i agree, but i think its easier and as good or better to use a filter
[18:33] <fnoble> syncing the FFT would be hard i think
[18:33] <Laurenceb> I'm thinking of making a GPS syncronised ADC at some point, just a little unit with USB and audio in
[18:33] <Laurenceb> so plug in your scanner, and stick it on your usb port
[18:33] <fnoble> hmm, you could use the PPS output of the GPS
[18:33] <Laurenceb> exactly
[18:34] <fnoble> and a (D)PLL to divide that down to your baud rate
[18:34] <Laurenceb> my v2 radio board is designed so you can do this
[18:34] <Laurenceb> at the TX end
[18:34] <fnoble> but why not use a filter and not have to worry?
[18:34] <Laurenceb> its not as efficient
[18:34] <fnoble> why?
[18:35] <fnoble> i think it has the potential to be more efficient
[18:35] <Laurenceb> you dont have as much control over the bandpass shape
[18:35] <Laurenceb> *passband
[18:35] <fnoble> you do, and with an FFT, how do you choose how many and which bins to sample?
[18:36] <fnoble> im thinking digital filter
[18:36] <Laurenceb> if you have an "orthogonal" FFT theres no crosstalk between the 0 and 1 channels
[18:36] <Laurenceb> thats not possible with filters
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[18:36] <Laurenceb> well an FFT is a digital filter, only operating over discreet windows
[18:36] <fnoble> it is if the filters have no overlap
[18:36] <Laurenceb> exactly
[18:37] <Laurenceb> hence "orthogonal" in OFDM used in DVBT and other schemes
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[18:38] <Laurenceb> but I'm not sure how they achieve the time syncronised windows
[18:38] <fnoble> with a filter you can match up exactly the spectra of the radio output, which gives theoretically optimal reception
[18:38] <Laurenceb> well your ideal spectra is a delta function
[18:38] <fnoble> with an FFT, maybe you can do this by choosing bins, maybe weighting how much you take from each bin, but its harder
[18:38] <Laurenceb> ideally 0 is bin n, 1 is bin n+1
[18:39] <fnoble> and deciding which bins to choose from is the same as designing the filter, only with another level of abstraction
[18:40] <fnoble> but the frequency will drift, and the spectra isnt as simple as a delta function
[18:40] <Laurenceb> I'd do it with an Icom scanner, so you could retune the scanner to keep 0 and 1 in the same bins
[18:40] <fnoble> if your bins are too wide you let in more noise and your SNR drops
[18:40] <Laurenceb> ad that could be controlled using hamlib
[18:41] <fnoble> when i say wide, i mean also if they are the wrong shape, the response should drop off at the sides
[18:41] <Laurenceb> your bins have to be 1 data bit long
[18:41] <Laurenceb> if your going for the orthogonal case
[18:41] <fnoble> i dunno, just sounds like overcomplication
[18:41] <Laurenceb> maybe, but it gives the best performance
[18:41] <fnoble> i dont see how it does
[18:42] <fnoble> a filter can be made to act like a FFT bin
[18:42] <Laurenceb> your not getting any noise into the system you dont have to
[18:42] <fnoble> but i think it can go further and match the output spectra more closely
[18:43] <fnoble> i will find the paper i read on it, that explained the idea to me
[18:43] <Laurenceb> ok
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[18:45] <fnoble> http://rfwireless.rell.com/pdfs/TN_WJfsk.pdf
[18:47] <fnoble> it doesnt make a comparison with FFT, but explains about how achieving good performance is all about matching the input filter response to the radio spectrum
[18:47] <fnoble> which i think is easier to do with a filter than an FFT
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[18:49] <Laurenceb> true
[18:49] <Laurenceb> but its from 1980
[18:49] <Laurenceb> before dsp
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[18:52] <fnoble> doesnt matter
[18:52] <fnoble> the point is you need to match the spectra, if you can do that with FFT then ok, but I dont see how to
[18:56] <Laurenceb> an FFT isnt just a top hat function
[18:57] <Laurenceb> http://www.teemach.com/FFTProp/FFTProperties/FFTProperties.htm
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[19:02] <Laurenceb> ok, I think that as there are just two frequencies of interest, you can multiply by locally generated signals
[19:03] <Laurenceb> like a two frequency descreet fourier transform
[19:03] <Laurenceb> then integrate the output power difference over your window positions ( found from the GPS 1PPS)
[19:05] <fnoble> well, do as you wish
[19:05] <Laurenceb> :P
[19:05] <fnoble> but i still dont see how it could be better than filters :p
[19:05] <fnoble> because i think filters are optimum in theroy
[19:05] <fnoble> if you get the filter response right
[19:06] <Laurenceb> your FFT respons should be "right"
[19:06] <Laurenceb> at the sub bin level, it should match the TX spectrum in the same way your filter would
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[19:06] <fnoble> so maybe you could get it to perform the same
[19:06] <fnoble> but not better
[19:07] <fnoble> and there are more what ifs
[19:07] <fnoble> bbiab
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[19:09] <Laurenceb> we'll have to agree to disagree :P
[19:10] <Cooleo> Gah, Im screwed. French exam tommorow. Pfft. Cant speak french to save my life.
[19:11] <Laurenceb> GCSE?
[19:11] <Laurenceb> "#I cant speak french...."
[19:11] <Cooleo> Yep. Mock tommorow, Actual one May first.
[19:11] <Laurenceb> ok, not so bad
[19:11] <Cooleo> Haha, if only there was such a channel.
[19:12] <Cooleo> I dont mind the rest, but I cant do my oral exam, just because I suck at french. and I cant remeber like a 2 minute presentation in my head in a forgien langauge
[19:13] <Laurenceb> http://www.youtube.com/watch?v=ZIMzh7y_Gbc
[19:13] <Cooleo> Haha.
[19:13] <Cooleo> Ill burst in my exam singing that
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[19:16] Nick change: Laurence1 -> Laurenceb_
[19:17] <Cooleo> Hmm, Made an Internal Battery mod for my La Fonera. Looks quite nice now
[19:19] <natrium42> hi
[19:20] <Cooleo> Hey
[19:24] <natrium42> i want to go fly something :S
[19:24] <Cooleo> Theres not much pressure diffrence at 100 Meters is there? Im just thinking about using a Li-On battery for my first test.
[19:24] <Cooleo> Natrium42, FSX?
[19:25] <natrium42> dunno if i still have it installed
[19:25] <natrium42> but i mean, physically
[19:25] <natrium42> r/c airplanes or balloons
[19:25] <Cooleo> Oh right.
[19:32] <Laurenceb_> I'm bidding on an rc parafoil
[19:32] <Laurenceb_> seller looks dodgy
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[19:32] Nick change: Laurenceb_ -> Laurenceb
[19:33] <Cooleo> You've always got Paypal protection right.
[19:34] <Laurenceb> its more a case of the fact they are bidding against me
[19:34] <Cooleo> Lol.
[19:34] <natrium42> Laurenceb, just use a sniping service :P
[19:34] <Cooleo> Maybe they dont want to sell it anymore so they are bidding on it
[19:34] <natrium42> http://www.gixen.com/
[19:34] <natrium42> it's teh free
[19:40] <Cooleo> Eurgh. Melting plastic smells.
[19:41] <natrium42> hehe
[19:41] <natrium42> getting high on the fumes?
[19:42] <Cooleo> Hehe, I wish. What I need right now :p
[19:42] <Cooleo> My drill bit broke, So i've been having to make holes in the plastic with screw drivers.
[19:42] <natrium42> lol
[19:43] <Cooleo> >.<
[19:43] <Cooleo> Then I just found out my switch is too big for my casing so it sits out of the top which looks ugly as heck
[19:43] <Laurenceb> drill bits are cheap ;P
[19:44] <Cooleo> Yeah, but every bit of my cash is going towards this atm :P.
[19:44] <Cooleo> Although, Might take a trip to poundland tommorow
[19:44] <Laurenceb> I'm going to mod this parafoil so its autonomous
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[19:44] <Laurenceb> If the seller doesn tfeel the need to bid on it any more, it'll cost me less than a good servo :D
[19:46] <kc0wys_> hello, all
[19:46] <natrium42> hi kc0wys_
[19:47] <natrium42> Cooleo, just make a couple o websites for people and it should be enough
[19:48] <Cooleo> Hmm, I already Admin for a few people, I might call on my advertisers for next months fee.
[19:49] <Cooleo> Ill go Pawn my watch :)
[19:51] <natrium42> lol
[19:53] <Cooleo> Huzzah, Should be getting Helium next weekend
[19:55] <Cooleo> £17.64 from ASDA :)
[20:23] <fnoble> really? how much do yo get for that?
[20:25] <Cooleo> I think 50 x 9 Inch balloons
[20:26] <Cooleo> ill just check online
[20:26] <Cooleo> Sorry, 30 x 9 inch
[20:28] <Cooleo> Is that expensive?
[20:31] <fnoble> just thinking it might not be enough to fill a weather balloon
[20:31] <fnoble> probably will be enough for one fill
[20:33] <Cooleo> Its not for a weather balloon this time :)
[20:34] <fnoble> whats it for?
[20:34] <Cooleo> My 100 Meter Photographic Test :P.
[20:34] <fnoble> ah i see
[20:34] <Cooleo> Onesec
[20:34] <Cooleo> http://www.euphoria-radio.com/blog
[20:34] <Cooleo> Check the first post :)
[20:35] <Cooleo> Its even got the diagram of what its going to look liek
[20:35] <Cooleo> *like
[20:35] <Cooleo> I decieded to make a small prototype (Proof of concept) because I wont have the money for the parts for the proper thing for a while yet
[20:36] <fnoble> cool, can prolly get away with a lot less than 3mm rope
[20:36] <fnoble> the ligher the rope, the higher you can go
[20:36] <fnoble> but 100m of 3mm rope will be quite heavy
[20:36] <Cooleo> Yeah, Thats what im thinking
[20:37] <Cooleo> 6 Balloons I think would lift it
[20:37] <fnoble> have you worked out how much lift you will get from each balloon?
[20:38] <fnoble> be sure not to do it near any pylons!
[20:38] <Cooleo> To lift 200 Grams of Weight, I would need 2 Grams of helium :p
[20:38] <Cooleo> *300 grams
[20:38] <Cooleo> Hehe, Luckily theres not very many near here
[20:39] <Cooleo> Will be cool to see the video afterwards.
[20:40] <Cooleo> I would let it go, But I would never see it again :P
[20:41] <natrium42> Cooleo, have you seen those guys in berlin? http://www.youtube.com/watch?v=2wajklGw21g
[20:41] <natrium42> used party balloons and a camera
[20:41] <natrium42> but it wasn't tethered, they followed it visually
[20:41] <Cooleo> Oh cool
[20:42] <Cooleo> How do you see if its too high up
[20:43] <natrium42> i guess they used almost neutral buoyancy at the ground level
[20:43] <natrium42> so it didn't go high
[20:43] <Cooleo> Hmm Yeah
[20:44] <Cooleo> But its wether I want to lose a digital camera or not if it goes missing
[20:46] <Cooleo> I havent seen any diposable Digital Cameras here in the UK
[20:47] <Cooleo> unless i get a cheap one on eBay
[20:48] <Cooleo> http://cgi.ebay.co.uk/Premier-DS3081S-Digital-camera-3MP_W0QQitemZ150236338533QQcmdZViewItem
[20:48] <Cooleo> Whats that sniping service?:)
[20:49] <natrium42> gixen.com
[20:49] <Cooleo> thank you!
[20:50] <Cooleo> Sniping on that camera
[20:50] <natrium42> i used it once to get a logic analyzer
[20:50] <natrium42> was a pretty good deal
[20:50] <natrium42> :)
[20:50] <Cooleo> If I get it for say £5, Its not a major loss if it goes away
[20:50] <Cooleo> Nice :)
[20:53] <Cooleo> Natirum42, Did you do the Oylmupus Camera Modification on the Wiki?
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[20:59] <jcoxon> evening all
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[21:05] <Cooleo> Yo.
[21:26] <jcoxon> hopefully my gps module will arrive tomorrow
[21:26] <Cooleo> Woo! Just won a 2.9 Megapixel Camera on ebay for 99p plus £1.75 postage
[21:27] <natrium42> jcoxon, do you know the boomerang project
[21:27] <natrium42> ?
[21:27] <jcoxon> yup
[21:27] <jcoxon> i've seen one ;-)
[21:27] <natrium42> one of the project members has contacted me :)
[21:27] <jcoxon> there is more then one person?
[21:28] <jcoxon> :-)
[21:28] <jcoxon> i thought it was one guy
[21:28] <jcoxon> yeah its a very simple but good design
[21:28] <natrium42> http://cmb.phys.cwru.edu/boomerang/
[21:28] <natrium42> are we talking about this?
[21:28] <jcoxon> wrong thing
[21:28] <jcoxon> haha
[21:28] <natrium42> :D
[21:28] <jcoxon> i was thinking gpsboomerang
[21:28] <natrium42> anyway, he asked for permission to use halo2 pictures :)
[21:29] <jcoxon> amazign
[21:29] <jcoxon> amazing
[21:29] <natrium42> yeah
[21:29] <natrium42> i should have asked them whether they have any graduate positions available
[21:30] <jcoxon> the department i worked with in Niger have a grad programme
[21:30] <jcoxon> but it would be in
[21:30] <jcoxon> cambridge
[21:30] <jcoxon> :-)
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[21:30] <jcoxon> in North America the big one is the Uni of Wyoming
[21:30] <jcoxon> I know 2 people down there. well they are acquitances
[21:32] <natrium42> cool
[21:32] <jcoxon> shame i don't want to do balloons for a living :-)
[21:33] <Cooleo> Hmm, New Camera 113 Grams. Not the lightest thing. Plus 80 for the other stuff, 200 grams roughly in total
[21:33] <Laurenceb> yesss won the parafoil
[21:33] <Laurenceb> £19 :D
[21:34] <Cooleo> Nice!
[21:35] <Laurenceb> http://cgi.ebay.co.uk/REMOTE-CONTROL-RC-PARACHUTE-PARAGLIDER-R-C-AIRGLIDER-UK_W0QQitemZ170211594640QQihZ007QQcategoryZ19164QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
[21:35] <Laurenceb> ^ one of those (soory huge url)
[21:36] <Cooleo> Oh cool
[21:36] <Cooleo> Will you detach teh little man? Or is he staying on for the ride?:)
[21:38] <Laurenceb> I'll probably rip off most of the bottom, its a bit homosexual
[21:39] <Cooleo> Haha! :P
[21:39] <Laurenceb> then use a servo for the steering, and make a foam "airframe" for the electronics
[21:40] <Laurenceb> it'll just be based on a mega168, using the gps and a melexis gyro
[21:41] <Laurenceb> not sure if I'll keep the motor...
[21:42] <Laurenceb> I've got a brushless that could power it better
[21:43] <Cooleo> Oh right
[21:51] <Laurenceb> I'll stick a cutdown on the top, I've just had a cool idea for reusing the cutdown cable as an RC antenna
[21:51] <Cooleo> Cool
[21:54] <Cooleo> Anyone got a use for a 14" LCD panel? I just took it out of a really old laptop
[22:01] <Laurenceb> I'm ok thanx
[22:01] <Laurenceb> ok, my idea is up on the wiki :D
[22:07] <Cooleo> Im off. G'night
[22:07] <Laurenceb> cya
[22:09] <Laurenceb> woops I cant add up, I got the parafoil for £16v:-)
[22:32] <Laurenceb> cya all
[22:32] <\\dan\\> bye
[22:37] <jcoxon> right
[22:37] <jcoxon> my code is complete
[22:38] <fnoble> for firefly 3?
[22:38] <jcoxon> yup
[22:38] <jcoxon> nice and simple
[22:39] <jcoxon> but works
[22:39] <fnoble> cool
[22:39] <jcoxon> tested most scenarios,
[22:39] <jcoxon> loss of gps
[22:39] <jcoxon> restart
[22:39] <jcoxon> no reception
[22:39] <fnoble> i was thinking, surely the firefly payload will be lighter than the goliath
[22:39] <jcoxon> its gone through my head
[22:41] <jcoxon> but i'm now not a big fan of gm862 modules
[22:41] <jcoxon> they really aren't that flexible
[22:42] <jcoxon> and remember that i'm having to use a external gps module
[22:42] <fnoble> ok, cool
[22:42] <jcoxon> lets see
[22:42] <jcoxon> interesting to see what alt we get on sat
[22:43] <jcoxon> that said
[22:43] <jcoxon> the forecast isn't great
[22:44] <fnoble> ok, what balloon are you flying?
[22:44] <jcoxon> haven't decided
[22:45] <jcoxon> really depends on the weather and the forecasts
[22:45] <jcoxon> up to a 1kg
[22:45] <fnoble> ok, we have a 1.5 i think in cambridge
[22:45] <fnoble> or it might be a 1.2
[22:45] <fnoble> if we feel ambitious
[22:46] <jcoxon> hehe
[22:46] <jcoxon> well rocketboy is around
[22:46] <fnoble> ah ok
[22:46] <jcoxon> if the forecasts were correct then we might just get a window but it would be a morning window
[22:46] <jcoxon> hopefully the jetstream forecasts will change
[22:47] <fnoble> ok, lets see what happens, a week is quite a long forecast
[22:47] <fnoble> anything could still happen
[22:47] <jcoxon> yeah
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[00:00] --- Mon Apr 21 2008