highaltitude.log.20090613

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[08:40] <jcoxon> morning all
[08:40] <jcoxon> Bill Brown Flight today with live streaming
[08:40] <jcoxon> ping natrium42
[08:45] <jcoxon> at http://www.batc.tv/ and go to WB8ELK
[08:45] <jcoxon> at 2.30 BST
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[10:56] <DanielRichman> What size resistor should I protect the LED-side of an opto isolator with?
[11:22] <SpeedEvil> ohms law
[11:22] <SpeedEvil> keep it under 20mA
[11:22] <SpeedEvil> the voltage across the LED should be 0.9V or so
[11:23] <DanielRichman> ok
[11:25] <SpeedEvil> (at 20mA it's 0.9V rather)
[11:29] <DanielRichman> Hmm. It appears to work with a 390 Ohm resistor, but shall I use a ~45 Ohm one just in case?
[11:30] <DanielRichman> SpeedEvil,
[11:31] <SpeedEvil> work out the current into the LED - look at the datasheet, workout the worst-case output current, and see if it's adequate
[11:31] <SpeedEvil> what's it driving?
[11:31] <SpeedEvil> and what sort of opto - optotransistor?
[11:32] <DanielRichman> http://www.maplin.co.uk/Module.aspx?ModuleNo=2198 - It's driving the camera shutter
[11:32] <SpeedEvil> have you measured the current the shutter draws?
[11:33] <DanielRichman> virtually nothing
[11:33] <SpeedEvil> the key is 'transfer ratio'
[11:33] <DanielRichman> Had the multimeter in 200mA mode (most sensitive) and it was still 0.00
[11:33] <SpeedEvil> no, it's not
[11:34] <SpeedEvil> put the multimeter on 200mV mode - and you've got a 200nA fullscale meter
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[11:34] <SpeedEvil> (if it has 1 megohm input impedence)
[11:34] <SpeedEvil> Anyway
[11:34] <DanielRichman> Besides, it's probably not a great reading since the shutter is multiplexed
[11:35] <SpeedEvil> the transfer ratio means - broadly that if you put in 10mA - say - you get transfer ratio * .13 (13% current transfer min) - from the output transistor
[11:35] <SpeedEvil> yeah
[11:36] <SpeedEvil> the low-current modes you can get on 200mV can be handy occasionally
[11:36] <DanielRichman> cool
[11:36] <SpeedEvil> (though are not very accurate, are very sensitive)
[11:37] <SpeedEvil> In practice - you probably want to go with a resistor that results in 20mA - simply as it's possible it may require more current at -55C - though this is unlikely
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[11:38] <SpeedEvil> Or at least try it to see if it triggers with 2* what you have, so you know you've got the margin
[11:38] <SpeedEvil> 2* the resistance - half the current that is
[11:38] <DanielRichman> I know it triggers with 390R
[11:38] <DanielRichman> so I'll use 100R?
[11:39] <SpeedEvil> yes, that should work fine then.
[11:39] <SpeedEvil> and give you lots of margin
[11:40] Action: SpeedEvil needs coffee.
[11:40] <SpeedEvil> brb
[11:58] <DanielRichman> It works!
[12:00] <SpeedEvil> So does my coffee.
[12:00] <SpeedEvil> :)
[12:00] <DanielRichman> :)
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[12:02] <DanielRichman> Today's featured article: The British Empire :)
[12:04] <sbasuita_> DanielRichman, perhaps it has something to do with the men with funny hats marching round on bbc 1
[12:07] <DanielRichman> How do you connect the 1/4wave antenna to the radiometrix? Coax soldered directly to ntx2 pins?
[12:07] <sbasuita_> DanielRichman, yeh
[12:07] <DanielRichman> I guess soldering the pins to a trace on the pcb, then connecting that trace to the antenna is a bad idea
[12:07] <sbasuita_> DanielRichman, bnc connector on the pcb?
[12:07] <SpeedEvil> as long as it's a short trace
[12:07] <DanielRichman> it's ~2cm
[12:07] <DanielRichman> 0.4mm wide
[12:07] <SpeedEvil> is the PCB double sided?
[12:07] <DanielRichman> no
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[12:11] <sbasuita_> home hub is killing me....
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[12:11] <DanielRichman> and your file transfer -.-
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[12:12] <sbasuita> DanielRichman, can you put a connector on the pcb so we can swap the antennas?
[12:12] <DanielRichman> sbasuita, no.
[12:12] <sbasuita> DanielRichman, why?
[12:12] <DanielRichman> because I have already etched the pcb
[12:12] <SpeedEvil> hot-melt works
[12:12] <DanielRichman> and I don't have a female BNC connector
[12:13] <sbasuita> DanielRichman, its not like there's a rush to launch
[12:13] <SpeedEvil> Also - BNC is stupidly large
[12:13] <DanielRichman> sbasuita, it's a bad idea
[12:14] <SpeedEvil> but - practically - resoldering takes a minute.
[12:14] <sbasuita> k
[12:15] Action: DanielRichman solders in the radiometrix
[12:15] <DanielRichman> but doesn't solder the three tx out pins
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[12:20] <DanielRichman> dok
[12:20] <DanielRichman> **atmega is now on air
[12:21] <DanielRichman> and another battery is flat.
[12:22] <DanielRichman> Only two things left are the aerial and the external temperature sensor
[12:22] Nick change: kingj -> KingJ
[12:41] <SpeedEvil> And the spanish inquisition!
[12:46] <DanielRichman> sbasuita,
[12:46] <DanielRichman> I need a few packs of those batteries
[12:46] <sbasuita> k
[12:46] <sbasuita> come and pick them up
[12:46] <DanielRichman> just bring them in on monday
[12:47] <DanielRichman> sbasuita, Is your homehub stable now?
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[12:51] <sbasuita_> (that wasn't the homehub)
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[13:17] <cuddykid_> hi guys! Is there any picture or explanation of how to build a simple cutdown device? I am off to Maplin soon, so was wondering what to look out for
[13:20] <SpeedEvil> there aare some on the wiki - try searching 'cutdown'
[13:20] <SpeedEvil> Some nichrome wire is popular - though I don't know if they do that
[13:20] <DanielRichman> Never tried it myself - or even considered it, but there's the explosive type, the hotwire through rope type, and the mechanical let-go type
[13:22] <cuddykid_> thanks, i will probably look for something like nichrome wire to burn and release balloon
[13:22] <SpeedEvil> I prefer high-temperature ceramic resistors that are rated for 350C
[13:23] <SpeedEvil> apply 1W, and a minute or so later, the resistor rises through 100C
[13:23] <SpeedEvil> a little later, it's at 180C, and that'll cut most any plastic
[13:24] <cuddykid_> i will look for some, they sound perfect!
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[14:24] <sbasuita> Awww... alpha isn't doing my linear programming for me :(
[14:52] <sbasuita> jcoxon, any news on that launch stream?
[14:52] <sbasuita> i'm at batc.tv but nothing is streaming on the channel
[14:54] <sbasuita> Ah, nevermind. Chat says stream starts about half 3
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[16:12] <Laurenceb> hi
[16:13] <Fighter1405> Hey
[16:13] <Laurenceb> http://www.youtube.com/watch?v=wSIWpFPkYrk
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[18:28] <Fighter1405> Heya
[18:29] <sbasuita> Fighter1405, hallo
[18:30] <Fighter1405> How are you doing?
[18:31] <sbasuita> very tired
[18:31] <sbasuita> not sure why
[18:31] <Fighter1405> Ouch :(
[18:32] <sbasuita> more like: sigh
[18:32] Action: SpeedEvil is also very tired.
[18:32] <SpeedEvil> I suspect it may be because I got 4h sleep last night though.
[18:33] <sbasuita> sleep is such a pain...
[18:33] <jcoxon> hey all
[18:34] <jcoxon> did bill brown launch
[18:34] <SpeedEvil> I'm going to sleep again.
[18:34] <jcoxon> night SpeedEvil
[18:35] <sbasuita> jcoxon, doesn't look like it judging by the stream
[18:35] <sbasuita> jcoxon, or the lack of
[18:37] <jcoxon> oh well
[18:37] <jcoxon> usually its quite good
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[18:39] <Fighter1405> What communication options are available without a license?
[18:41] <sbasuita> Fighter1405, depends on your country
[18:41] <Fighter1405> UK
[18:41] <DanielRichman> Balloon to ground?
[18:41] <Fighter1405> Most likely yes
[18:41] <sbasuita> Fighter1405, ok, we're using radiometrix modules which work on unlicensed parts of the 70cm band
[18:41] <Fighter1405> grount to balloon sounds more complex
[18:41] <Fighter1405> *ground
[18:42] <SpeedEvil> it is.
[18:42] <Fighter1405> What sort of range do they have sbasuita?
[18:42] <sbasuita> you're limited to 10mW transmit power
[18:42] <SpeedEvil> Fighter1405: few hundred Km
[18:42] <sbasuita> Fighter1405, http://www.radiometrix.co.uk/products/ntx2nrx2.htm
[18:42] <SpeedEvil> at 50bps
[18:42] <Fighter1405> Thanks
[18:42] <Fighter1405> I'm assuming there is no age limit for launching these things?
[18:42] <DanielRichman> Fighter1405, basically, in the radio link, there's gotta be lots of beef somewhere, and the other bit can be weak: Ie. Beefy transmitter, weak reciever or weak transmitter and beefy receiver.
[18:42] <sbasuita> Fighter1405, NTX2 and NRX2 are transmit and receive respectively (but you already worked that out ;P)
[18:43] <DanielRichman> A beefy transmitter requires a license
[18:43] <sbasuita> Fighter1405, no
[18:43] <Fighter1405> Great :p
[18:43] <Fighter1405> Communication seemed like a good place to start, being what I know least about
[18:44] <sbasuita> Fighter1405, just ask lots of questions and you'll soon be up to speed
[18:44] <Fighter1405> Thanks, I will do. This channel seems like a great resource
[18:45] <Fighter1405> Hoping to eventually launch something from cambridge
[18:46] <sbasuita> Yeah, that seems like the UK's de-facto launch site
[18:47] <Fighter1405> So that transmitter and reciever works by default without a license?
[18:47] <sbasuita> Fighter1405, i wouldn't recommend using the radiometrix receiver
[18:47] <sbasuita> Fighter1405, but definitely the trasmitter is good to go
[18:47] <Fighter1405> ok, what reciever would you recommend? Something just plugged into a laptop?
[18:49] <sbasuita> Fighter1405, there are a wealth of radio receivers - I wouldn't know where to begin
[18:49] <sbasuita> Fighter1405, jcoxon kindly lent me his yaesu ft-790r (70cm band transceiver) which is working like a charm
[18:49] <Fighter1405> Is it standard to use a laptop to interpret the information? Or more standard to go with an external device?
[18:50] <sbasuita> Fighter1405, you would use a normal transceiver, and connect the audio out of that to the audio in of your laptop
[18:50] <sbasuita> then use software to do digital decoding
[18:50] <Fighter1405> I see, vaguely :p
[18:50] <Fighter1405> Has anyone tried using an Arduino as the main processor for a flight?
[18:51] <sbasuita> Fighter1405, we were going to, and it was working
[18:51] <sbasuita> but we're now using an atmega162
[18:51] <sbasuita> same architecture as the arduino
[18:52] <Fighter1405> What advantage is gained?
[18:52] <Fighter1405> I believe the ATmega168 has been used independantly on flights before, just never seen it actually in an Arduino
[18:52] <sbasuita> Fighter1405, don't need all the extra bits on the arduino
[18:52] <Fighter1405> Ah I see, fair enough
[18:53] <sbasuita> much cheaper without
[18:53] <sbasuita> and smaller
[18:53] <sbasuita> etc
[18:53] <Fighter1405> got it
[18:53] <Fighter1405> Do you use secondary communication system in case the first fails?
[18:54] <DanielRichman> If you really wanted to do that you'd have to send up two flight computers
[18:54] <DanielRichman> and two transmitters
[18:54] <sbasuita> Fighter1405, we're using gsm as well
[18:54] <DanielRichman> 'cause everything could go wrong.
[18:54] <sbasuita> to sms us the co-ordinates
[18:54] <sbasuita> its basically an old hacked mobile phone
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[18:54] <Fighter1405> Sounds like a good idea :p Seperate GPS chip as well?
[18:54] <sbasuita> but that only works on the ground
[18:54] <DanielRichman> Fighter1405, On the Arduino point - have you programmed for AVR or Arduino before?
[18:55] <Fighter1405> Programmed for Arduino, never used an AVR programmer though
[18:55] <DanielRichman> ok. How good are you at C?
[18:55] <sbasuita> didn't see that one coming....
[18:55] <Fighter1405> Uhh, sketchy at best :p I've done a bit in it, but most of what I've done before has been web development
[18:55] <Fighter1405> PHP, some python etc.
[18:56] <DanielRichman> Okey. If you can handle it ( :) ) then I'd highly reccomend not using the Arduino IDE
[18:56] <DanielRichman> PHP will help you with C to a certain extent ;)
[18:56] <DanielRichman> http://alienproject.files.wordpress.com/2009/06/alien1.pdf - Our Schematic
[18:56] <DanielRichman> http://alienproject.files.wordpress.com/2009/06/alien1b.pdf - Our PCB (Single sided, produced at school via chemical process)
[18:56] <DanielRichman> http://code.google.com/p/alien-flightcomputer/source/browse/#svn/trunk/alien1/atmega162/final - Our code
[18:57] <Fighter1405> Thanks for that :)
[18:57] <Fighter1405> Does using pure C give you faster computation, lower power drain?
[18:58] <DanielRichman> _better_ computation. The Arduino library was written by a flipper handed monkey
[18:58] <Fighter1405> Got it :p
[18:58] <DanielRichman> But on top of that - it is faster, smaller, more real-time
[18:58] <DanielRichman> I actually stopped using the Arduino library because it frustrated me to the point of rm -Rf
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[18:58] <Fighter1405> Thanks, I'll be sure to look through your schematics and code
[18:59] <DanielRichman> One errata: The resistors used to protect the opto isolator should be 100R not 2K7
[18:59] <DanielRichman> but that really depends on the Opto Isolator IC that you use
[18:59] <Fighter1405> ok
[18:59] <DanielRichman> if you choose to use one
[18:59] <Fighter1405> Sorry to keep asking questions :p Any good tutorials you'd adivce on the whole RF communication thing? I've really done nothing in it before
[18:59] <Fighter1405> *advise
[18:59] <DanielRichman> You're forcing me to plug my own stuff :D
[18:59] <DanielRichman> http://alienproject.wordpress.com/2009/06/12/a-motherload/
[18:59] <Fighter1405> Haha, thanks :p
[18:59] <DanielRichman> try that - it'll probably only make half-sense, so ask away
[19:00] <Fighter1405> Will do, I'll read it now
[19:00] <sbasuita> Fighter1405, also
[19:00] <sbasuita> .wik rtty
[19:00] <herabot> "Radioteletype (RTTY) is a telecommunications system consisting of two or more teleprinters using radio as the transmission medium." - http://en.wikipedia.org/wiki/Radioteletype
[19:00] <jcoxon> i guess you could view RTTY as being serial comms over wireless
[19:00] <Fighter1405> I'll read that too, thanks :)
[19:00] <sbasuita> yep
[19:01] <DanielRichman> I linked a great wikipedia scope-trace of RS232 - the same protocol - in that post
[19:01] <akawaka> nice acronym
[19:03] <jcoxon> Fighter1405, something fun to play with http://websdr.ewi.utwente.nl:8901/
[19:03] <sbasuita> jcoxon, more like something for
[19:03] <sbasuita> ...
[19:03] <sbasuita> something for me to do
[19:03] <sbasuita> i remember one of the guys at the radio club meeting said to google websdr
[19:04] <DanielRichman> Have fun!
[19:04] Action: DanielRichman goes to eat
[19:04] <jcoxon> its very cool
[19:04] <DanielRichman> How does it work?
[19:04] <jcoxon> good chance to learn about decoding stuff
[19:04] <sbasuita> DanielRichman, plug a radio into a computer and add TCP
[19:04] <DanielRichman> sbasuita, I was wondering more about the multi-bands-at-once deal
[19:04] <jcoxon> sbasuita, its a lot mor ethen that
[19:05] <jcoxon> there isn't much of a radio - is a software radio
[19:05] <akawaka> johan built on of those sdrs
[19:05] <DanielRichman> Oh I get it
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[19:05] <Fighter_1405> Eek
[19:05] <sbasuita> oh look: java and firefox both spiral into infinite loops
[19:05] <DanielRichman> All the band-selection etc. is done by the computer
[19:05] <Fighter_1405> That last link crashed my firefox
[19:05] <jcoxon> yeah
[19:05] <sbasuita> as soon as i turned off noscript....
[19:05] Action: DanielRichman doesn't have java installed - win!
[19:05] <DanielRichman> be back later.
[19:05] <sbasuita> DanielRichman, then have fun with the radio
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[19:05] <Fighter_1405> So I missed anything you said between the link and then :(
[19:06] Tiger^ (i=tygrys@moo.pl) got netsplit.
[19:06] rcaron (n=rcaron@c-75-68-116-90.hsd1.nh.comcast.net) got netsplit.
[19:06] <sbasuita> Fighter_1405, nothing important
[19:06] Nick change: Fighter_1405 -> Fighter1405
[19:06] <Fighter1405> ok, thanks
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[19:06] <sbasuita> Fighter_1405, i recommend you get yourself a desktop irc client though ; )
[19:06] <Fighter1405> I have mIRC on my laptop, just not on this desktop :p
[19:08] <akawaka> i wonder if the radio manufacturers are resisting sdr in anyway
[19:08] <sbasuita> DanielRichman, picture at the bottom: http://websdr.ewi.utwente.nl:8901/info.html
[19:08] <sbasuita> (how it works)
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[19:09] <akawaka> any cheap laptop is capable of doing much more processing than their highend radio models
[19:10] <sbasuita> ok, so any 'websdr' crashes my firefox and java
[19:10] <sbasuita> great
[19:10] <Fighter1405> Mine too
[19:11] <jcoxon> it works well in safari if that helps ;-)
[19:14] <Fighter1405> DanielRichman: Did you use the NTX2 for that blog aritcle as well?
[19:14] <sbasuita> Fighter1405, yep
[19:14] <sbasuita> Fighter1405, we're working on the same project btw
[19:14] <Fighter1405> Great :)
[19:14] <Fighter1405> You planning on launching in cambridge too?
[19:14] <sbasuita> Fighter1405, yes, with the help of cusf
[19:15] <Fighter1405> Seems ideal without the NOTAM complications
[19:15] <sbasuita> complications?
[19:15] <Fighter1405> No need to issue a NOTAM if you use cambridge from what I understand
[19:16] <sbasuita> ah right
[19:16] <sbasuita> you still have to get clearance from the air authorities
[19:16] <Fighter1405> Really? I thought ukhas had that covered
[19:17] <sbasuita> ukhas is just a jumble of people who do the same thing
[19:17] <sbasuita> not really a formal organisation
[19:17] <Fighter1405> Ah, well that hurdle can be covered nearer the time I guess :p
[19:18] <Fighter1405> And I saw your school is making the pcb for you, any tips on persuading them to do that? :p
[19:19] <sbasuita> making it for us?
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[19:19] <sbasuita> the electronics department: "there are the chemicals; use them"
[19:19] <Fighter1405> Well, letting you use their facilities to produce it
[19:20] <Fighter1405> I'll try to persuade our electronics department to do the same then :p
[19:20] <sbasuita> cool
[19:20] <Fighter1405> You study electronics now?
[19:21] <sbasuita> Schools generally do let you use their facilities though.... play basketball in the gym, use the equipment in the workshop, etc...
[19:21] <sbasuita> Fighter1405, daniel, does; i don't
[19:21] <sbasuita> :/ comma usage
[19:21] <Fighter1405> Fair enough, my school wouldn't offer an A level electronics course :(
[19:21] <sbasuita> we're doing GCSe
[19:21] <Fighter1405> Ah yeah, I GCSE electronics
[19:22] <Fighter1405> *I did
[19:23] Nick change: KingJ -> kingj
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[19:23] <Fighter1405> Where did you get the NTX2 from? Rapid electronics doesn't appear to stock it
[19:23] <sbasuita> Fighter1405, we called up radiometrix and they sent us a free one
[19:23] <Fighter1405> Oh, very nice :p
[19:24] <Fighter1405> And you borrowed the reciever?
[19:24] <sbasuita> Fighter1405, yes
[19:25] <sbasuita> transceivers are very expensive
[19:25] <Fighter1405> Oh :(
[19:25] <sbasuita> perhaps seek the help of a local amateur radio club?
[19:25] <Fighter1405> Maybe, if I knew of one :p How expensive is very expensive?
[19:26] <sbasuita> Fighter1405, hundreds of pounds
[19:26] <Fighter1405> Yeah ok, I'll look into that then
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[19:27] Nick change: kingj -> KingJ
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[19:28] <Laurenceb> hi
[19:28] <Fighter1405> Hey
[19:31] Action: jcoxon is working on Peg VI
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[19:33] <jcoxon> ping natrium42
[19:33] <natrium42> hi jcoxon
[19:34] <DanielRichman> Fighter1405, correction - the electronics department didn't make it, I made it ;)
[19:34] <DanielRichman> using their stuff. The Electronics teacher likes me anyway
[19:35] <DanielRichman> sbasuita, gonna grab some photos of this flight comptuer
[19:35] Action: DanielRichman gets some big a3 backing white paper
[19:37] <DanielRichman> Anyone got any idea which way up this gps antenna is meant to be ;) ?
[19:38] Nick change: KingJ -> kingj
[19:38] <Fighter1405> That's what I meant DanielRichman :p Using their chemicals and board would be ideal though
[19:38] <DanielRichman> Yes. The school has a bubble etch machine
[19:39] <Fighter1405> Just emailed radiometrix about their transmitter anyway, so I'll see what they say
[19:39] <DanielRichman> but the photo developer had ran out - so I had to mix some more
[19:39] <Fighter1405> Same as my school, if I can persuade them to let me use it
[19:39] <DanielRichman> if you have trouble, get the science department interested, then sell it to the electronics as a school project
[19:40] <Fighter1405> Maybe, given I want to do computer science at uni I'm sure I can persuade them it is ideal for UCAS anyway ;)
[19:41] <Fighter1405> What requirements are there for the transciever to be used? Will most work?
[19:43] <jcoxon> Fighter1405, you want 70cm (430-440MHz) and SSB
[19:43] <Fighter1405> SSB?
[19:43] <jcoxon> unfortunately the SSB is what adds the cost, most receivers are just FFM
[19:43] <jcoxon> FM*
[19:43] <jcoxon> single side band
[19:43] <Fighter1405> Got it, thanks
[19:43] Nick change: kingj -> KingJ
[19:46] <SpeedEvil> How often have 'we' seen co-channel intereference, and might narrowband FM work in the absence of that - just coupled into a UART, with DC level restoration.
[19:46] <SpeedEvil> a narrowband FM reciever
[19:48] Nick change: KingJ -> kingj
[19:49] <Fighter1405> So this would work ok jcoxon : http://www.rigpix.com/kenwood/ts450s.htm
[19:50] <SpeedEvil> not for 433MHz
[19:50] <sbasuita> only goes up to 30MHz
[19:50] <Fighter1405> oh ya
[19:51] <SpeedEvil> search ebay for titles and descriptions for something like (70cm,uhf,433M*) (ssb,single) in the radio category
[19:52] Nick change: kingj -> KingJ
[19:55] <Fighter1405> Thanks, that was a much better search :)
[19:55] <Fighter1405> What's something like this for? http://cgi.ebay.co.uk/RF-Monolithics-DR3001-433MHz-115kbps-Transceiver_W0QQitemZ120424021997QQcmdZViewItemQQptZUK_Gadgets?hash=item1c09d4bfed&_trksid=p3286.c0.m14&_trkparms=65%3A12|66%3A2|39%3A1|72%3A1690|240%3A1318|301%3A1|293%3A1|294%3A50
[19:55] <jcoxon> thats for simple short distance comms
[19:56] <sbasuita> Fighter1405, looks like send serial data to one, pop out the serial of the other type deal
[19:56] <Fighter1405> But not suitable for long range communications needed for the balloon
[19:59] <RocketBoy> my logo: http://www.bbc.co.uk/iplayer/images/series/b00drxss_512_288.jpg
[20:00] <jcoxon> hehe brilliant
[20:01] <Fighter1405> Sorry to keep asking, but would this work: http://cgi.ebay.co.uk/Yaesu-FT-8800R-VHF-UHF-Dual-band-Transceiver-MH-48A6J_W0QQitemZ110334935647QQcmdZViewItemQQptZUK_ConsumerElectronics_SpecialistRadioEquipment_SM?hash=item19b079825f&_trksid=p3286.c0.m14&_trkparms=65%3A12|66%3A2|39%3A1|72%3A1690|240%3A1318|301%3A0|293%3A1|294%3A50
[20:02] <Fighter1405> Except I can't see an output on it :(
[20:03] <jcoxon> doesn't do ssb unfortunately
[20:03] <sbasuita> Fighter1405, it will almost certainly have one
[20:03] <SpeedEvil> It says 'so you don't hve to waste time scanning ssb' whichc is catching the search
[20:03] <SpeedEvil> but it doesn't do ssb
[20:04] <Fighter1405> Ah, can't believe I missed that :(
[20:04] <Fighter1405> So you really are looking at £400+ for a transciever that would work
[20:04] <jcoxon> or slightly older transcivers
[20:04] <jcoxon> the FT790r is usually about 100 pounds
[20:04] <jcoxon> thats teh one that sbasuita and co have
[20:04] <Fighter1405> That is more doable
[20:05] <Fighter1405> Not on ebay though :p
[20:05] <sbasuita> but if you're going to buy a transceiver, you want one that's going to be able to last you
[20:05] <sbasuita> so you might want multiple bands
[20:05] <Fighter1405> I was thinking more one that could be sold for what you bought it for if you no longer needed it
[20:06] <sbasuita> ah, that's a good point
[20:07] <SpeedEvil> ebay can work werll - if you know how to use it.
[20:07] <SpeedEvil> the signs to look out for with sellers.
[20:07] <DanielRichman> Flight computer pictures coming up
[20:07] <Fighter1405> I don't mind buying one if I can sell it on again, but I really don't want to lose more than £500-£1000 on the whole project (is that reasonable?)
[20:07] <DanielRichman> In absence of sbasuita's epic SLR, they leave quality to be desired, but meh
[20:08] <sbasuita> DanielRichman, i don't have an slr
[20:08] <SpeedEvil> Fighter1405: the loss on an icom FT790R or something on ebay is unlikely to be more than 30 quid say
[20:08] <SpeedEvil> the loss on the above would be much more
[20:08] <Fighter1405> That's no probelm then
[20:08] <DanielRichman> sbasuita, whatever camera I used when I came round your house - it's amazing
[20:08] <sbasuita> Fighter1405, get your school to pay for it
[20:08] <sbasuita> Fighter1405, (the project)
[20:09] <Fighter1405> I really doubt they would
[20:09] <Fighter1405> What are the cost estimates on yours sbasuita ?
[20:09] <sbasuita> Fighter1405, nothing
[20:09] <sbasuita> Fighter1405, for us
[20:09] <DanielRichman> *virtually nothing*
[20:09] <Fighter1405> I mean, for the school to pay :p
[20:09] <sbasuita> Fighter1405, we got the gps, radio, sd storage free
[20:09] <sbasuita> Fighter1405, free batteries
[20:10] <sbasuita> Fighter1405, free radio
[20:10] <Fighter1405> Wow, how did you manage all that?
[20:10] <DanielRichman> We should rent out Alex Breton's service as a professional blagger
[20:10] <sbasuita> Fighter1405, just ask nicely
[20:10] <DanielRichman> HI! GCSE students, no moneyz, can has free stuff?
[20:10] <sbasuita> Fighter1405, school will pay for balloon, parachute
[20:10] <Fighter1405> And they do it?
[20:10] <sbasuita> yep
[20:10] <Fighter1405> Crazy :p
[20:10] <Fighter1405> Any advice on what companies? :p
[20:10] <sbasuita> Fighter1405, energizer will happily send you 100 of their best AAs
[20:11] <sbasuita> Fighter1405, actually sd storage is school pay
[20:11] <sbasuita> Fighter1405, radio was radiometrix
[20:11] <sbasuita> Fighter1405, gps was donated by the great natrium42
[20:12] <Fighter1405> Standard AAs work? I was under the impression you had to use Lithium?
[20:12] <sbasuita> Fighter1405, they are lithium
[20:12] <Fighter1405> Wow, I'll phone them for sure then :p You just explained the project and they sent you some?
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[20:13] <sbasuita> Fighter1405, yep
[20:13] <Fighter1405> Hehe, great :p
[20:13] <sbasuita> Fighter1405, we asked for 24 batteries
[20:13] <sbasuita> Fighter1405, but they sent us 24 packs of four
[20:13] <Fighter1405> wow
[20:13] <sbasuita> Fighter1405, http://alienproject.wordpress.com/2009/04/04/energizer-motherload/
[20:14] <Fighter1405> I'll phone them for sure :p
[20:14] Nick change: KingJ -> kingj
[20:15] <Fighter1405> You called rather than emailed?
[20:16] <sbasuita> Fighter1405, yes
[20:16] <Fighter1405> ok, the UK office?
[20:16] <sbasuita> Fighter1405, i think so
[20:16] <DanielRichman> be careful, they might get pissed off if every single one of us starts phoning for freebies ;)
[20:17] <Fighter1405> True, true :p Not many other recognized battery makers to try though
[20:19] Nick change: kingj -> KingJ
[20:20] <DanielRichman> Photos up! http://alienproject.wordpress.com/2009/06/12/a-motherload/
[20:20] <DanielRichman> now I'm off to boot to windows and play a few games. See everyone later
[20:21] <DanielRichman> sbasuita,
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[20:25] Nick change: RocketBoy -> RocketBoy|Away
[20:29] Nick change: kingj -> KingJ
[20:30] <jcoxon> oooo looks good
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[20:59] <Laurenceb> nice
[21:00] <Laurenceb> I'd be careful not to touch the top of the gps antenna
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[21:00] <Laurenceb> they are easy to fry
[21:00] <Bluenarf> yea
[21:00] <Bluenarf> bittof oil and away you go!
[21:00] <Bluenarf> anyone ever interface to the COM port in C++ ?
[21:10] Nick change: Bluenarf -> EI5GTB
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[21:37] <Fighter1405> http://cgi.ebay.co.uk/YAESU-FRG-8800-COMMUNICATIONS-RECEIVER-HAM-CB-RADIO_W0QQitemZ400055323080QQcmdZViewItemQQptZUK_ConsumerElectronics_SpecialistRadioEquipment_SM?hash=item5d2527c9c8&_trksid=p3286.c0.m14&_trkparms=65%3A12|66%3A2|39%3A1|72%3A1690|240%3A1318|301%3A1|293%3A1|294%3A50
[21:37] <Fighter1405> Work or not? :p
[21:40] <jcoxon> ummm
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[21:40] <jcoxon> i think its only HF (up to 30Mhz
[21:40] <jcoxon> )
[21:41] <Fighter1405> Oops, I'm getting the Khz and Mhz mixed up
[21:41] <Fighter1405> I'm no good at this business of finding radios :p
[21:42] <jcoxon> it takes a bit of time
[21:42] <jcoxon> relatively cheap ssb radios are quite rare
[21:43] <Fighter1405> I'm seeing that :(
[21:44] <jcoxon> i think the best start for making a payload is to get a gps module working with your flight computer microprocessor
[21:44] <Fighter1405> I thought that the communications would be best, as I've had experience with most of the rest of it (had a go with a GPS unit before) but I've never used RF communications
[21:45] <jcoxon> just means that you've got something to do while you wait for a transciver
[21:46] <jcoxon> if not when sbatitsu and DanielRichman have finished with my radio you can borrow it
[21:46] <Fighter1405> Yeah, and there is no software solution? You need a hardware transciever
[21:46] <Fighter1405> Thanks for the offer :) That would be a great back up plan
[21:46] <jcoxon> my radio has been making the rounds
[21:47] <Fighter1405> It seems they are relatively rare :p
[21:47] <Fighter1405> Where are you based?
[21:47] <jcoxon> i'm in london
[21:47] <Fighter1405> Ah good, not too far from me
[21:48] <jcoxon> you could get a ntx2 and a nrx2
[21:48] <jcoxon> but for an actually flight the nrx2 isn't sensitive enough
[21:49] <Fighter1405> ok
[21:49] <jcoxon> but you are very welcome to use the UKHAS "Network"
[21:50] <jcoxon> which is when we all track with our receivers and feed the data into a centralised server which maps it nicely
[21:50] <Fighter1405> Network? :p
[21:50] <Fighter1405> Very nice
[21:50] <jcoxon> e.g. http://spacenear.us/tracker/
[21:50] <jcoxon> that was on wednesday
[21:51] <Fighter1405> still would need a reciever to test with though :(
[21:51] <jcoxon> yes, perhaps the nrx2 then
[21:51] <Fighter1405> So for that newtork the transciever just stays at cambridge and publishes the data it picks up to the internet?
[21:52] <Fighter1405> *network
[21:52] <jcoxon> well we use multiple receivers
[21:52] <jcoxon> so usually one in cambridge, one chasing in the chase car and then others dotted around (such as myself in London)
[21:53] <Fighter1405> Ah neat, I assume there is a protocol to be followed for that transmission then?
[21:53] <jcoxon> yeah
[21:53] <jcoxon> its often called the UKHAS standard
[21:53] <Fighter1405> Would they be willing to lend one for the chase car?
[21:54] <jcoxon> $$callsign,count,time,lat,lon,alt,other_data,more_custom_data
[21:54] <jcoxon> a checksum is optional but it does help
[21:54] <Fighter1405> And that link you sent, did that one land in the sea?
[21:54] <jcoxon> i'm sure something can be arranged
[21:54] <jcoxon> unfortunately yes
[21:55] <Fighter1405> Ouch :(
[21:55] <jcoxon> we don't aim for that
[21:55] <Fighter1405> How common is that?
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[21:55] <jcoxon> its getting less common as we are better at predictions
[21:55] <jcoxon> Fighter1405, http://wiki.ukhas.org.uk/list_of_launches
[21:55] <Fighter1405> Don't you wait for a less windy day>
[21:55] <jcoxon> yes
[21:55] <jcoxon> though they have been rare these past few months
[21:56] <jcoxon> (windy as in Jetstream windy rather then ground winds)
[21:56] <Fighter1405> More than I thought are lost then :(
[21:57] <jcoxon> its not an easy challenge
[21:57] <jcoxon> the last flight for an example very nearly didn't land in the sea
[21:57] <jcoxon> and went further then planned as the cutdown failed
[21:57] <Fighter1405> I'm sure, which makes me a little worried :p
[21:57] <jcoxon> just be very careful
[21:57] <Fighter1405> Given I've never done anything quite like it
[21:58] <jcoxon> e.g. you can use this: http://www.srcf.ucam.org/~cuspaceflight/predict/index.php
[21:58] <Fighter1405> For a cutdown you need ground to balloon communication as well I assume?
[21:58] <jcoxon> it'll
[21:58] <jcoxon> oops
[21:58] <jcoxon> ummm preprogrammed
[21:58] <jcoxon> ground to balloon is very difficult
[21:58] <jcoxon> hasn't been successfully done here in the uk
[21:58] <jcoxon> people are working on it
[21:58] <Fighter1405> How does the cut down work then?
[21:59] <jcoxon> there are a number of options
[21:59] <jcoxon> explosive cutdowns: http://wiki.ukhas.org.uk/ideas:flight_support#pyrotechnic_cutdown_device
[21:59] <jcoxon> or nichrome wire which gets hot and melts the line
[22:00] <Fighter1405> I meant, how do you trigger it to go off without grount to balloon?
[22:00] <jcoxon> prepogrammed so say when you reach an altitude of 20km
[22:00] <jcoxon> or after a set amount of time
[22:00] <jcoxon> or after distance from launch site
[22:00] <Fighter1405> Ah I see, clever
[22:01] <jcoxon> or if the payload goes outside a pre-set cutdown 'box'
[22:01] <jcoxon> as in its lat and long go outside a pre-set shape
[22:01] <Fighter1405> Neat
[22:02] <Fighter1405> Does the wind never blow west at cambridge?
[22:02] <jcoxon> rarely
[22:02] <jcoxon> well not as much
[22:02] <Fighter1405> That would be ideal I presume :p
[22:02] <jcoxon> indeed
[22:03] <jcoxon> ground winds are usually South Westerlies
[22:03] <jcoxon> and the JS is nearly always coming from the West
[22:04] <jcoxon> the best approach is to not rush making a payload
[22:04] <jcoxon> once its done do loads of testing
[22:04] <jcoxon> and then wait for a day to launch
[22:04] <jcoxon> might take a while but its a lot safer
[22:04] <DanielRichman> I wonder if we can test ours in a fridge
[22:04] <Fighter1405> Fair enough
[22:04] <jcoxon> fridge! freezer might be better
[22:04] <Fighter1405> Are most of the losses due to failure rather than incorrect predictions then?
[22:04] <DanielRichman> true. Perhaps I can get some liquid nitrogen
[22:05] <jcoxon> :-)
[22:05] <jcoxon> Fighter1405, yes, its hard to test properly
[22:05] <Fighter1405> I should imagine :p
[22:05] <jcoxon> but its good fun, worthwhile
[22:05] <jcoxon> if you see it as a challenge
[22:06] <Fighter1405> I'm sure, I'd just rather get the equipment back at the end for future possible launches :p
[22:06] <DanielRichman> One brainstormed idea to make an antenna involved using the school's laser-cutter to cut a boom out of acrylic and then shrink fit elements in for super accuracy.
[22:06] <Laurenceb> schools laser cutter ?!
[22:06] <jcoxon> DanielRichman, nice idea
[22:06] <DanielRichman> Hell yes, biatch
[22:06] <Laurenceb> do they have sharks as well?
[22:06] <jcoxon> Fighter1405, if you are sensible it'll come back
[22:06] <DanielRichman> No, but we could laser some sharks if we wanted
[22:07] <jcoxon> http://www.radioworld.co.uk/~radio/catalog/second-hand-yaesu-ft790-p-1741.html
[22:07] <DanielRichman> This one IIRC:
[22:07] <DanielRichman> argh. copy paste fail
[22:07] <DanielRichman> http://www.gravograph.co.uk/Engraving%20Machines/LS900.php
[22:07] <Fighter1405> That'll work jcoxon?
[22:07] <jcoxon> thats the one i have
[22:07] <jcoxon> DanielRichman, reading school?
[22:07] <DanielRichman> jcoxon, yes
[22:07] <jcoxon> my cousins went there
[22:08] <jcoxon> high achieving school!
[22:08] <DanielRichman> :)
[22:08] <Fighter1405> If you wanted to sell that back on ebay what do you reckon you'd get for it jcoxon?
[22:08] <jcoxon> 100
[22:08] Nick change: RocketBoy|Away -> RocketBoy
[22:08] <jcoxon> its quite an old radio, but very good at its job
[22:09] <jcoxon> you see these days most radios do multiple bands
[22:09] <Fighter1405> That's not such a bad loss then
[22:09] <jcoxon> but this one focuses on doing that band very well
[22:09] <jcoxon> hey RocketBoy
[22:09] <Fighter1405> And it just plugs straight in to the audio in on a laptop?
[22:09] <RocketBoy> yoyo
[22:10] <RocketBoy> FT790 = hard to beat
[22:10] <jcoxon> Fighter1405, yeah it has a 3.5mm jack speaker output
[22:10] <jcoxon> and that goes into the audio in on you computer
[22:10] <Fighter1405> Neat
[22:11] <jcoxon> then you run something like dl-fldigi to decode
[22:11] <Fighter1405> What are the other main expensive parts of the launch?
[22:11] <jcoxon> helium is getting more expensive unfortunately
[22:11] <Fighter1405> Balloon/Parachute/Helium/GPS ?
[22:11] <jcoxon> balloons vary in price depending on the size
[22:11] <Fighter1405> How much does it tend to be for the required helium?
[22:12] <jcoxon> http://www.randomsolutions.co.uk/
[22:12] <jcoxon> RocketBoy, what tank do you usually bring along?
[22:12] <jcoxon> its been a while since i've orderd my own helium
[22:12] <jcoxon> that link is the balloon supply we use (which is Rocketboy's webshop)
[22:13] <RocketBoy> I normally have two N20s - one part full the other full
[22:13] <Fighter1405> Great, for a basic payload what size balloon roughly?
[22:13] <RocketBoy> an N20 is about 5cu m of helium
[22:13] <RocketBoy> depends on weight
[22:13] <jcoxon> Fighter1405, over the years we've increased in size
[22:13] <jcoxon> but there isn't anything wrong with the smaller balloons
[22:13] <jcoxon> just won't go as high
[22:14] <RocketBoy> and desired ascent rate and height
[22:14] <Fighter1405> Fair enough, I'm not wanting to set any records the first time anyway :p
[22:14] <Fighter1405> And that nylon cord and those parachutes will work as well?
[22:14] <jcoxon> yes they are all tested
[22:15] <Fighter1405> Great, a good site to bookmark then
[22:15] <jcoxon> youv'e seen wiki.ukhas.org.uk?
[22:16] <Fighter1405> I've looked at it briefly yes
[22:16] <jcoxon> cool
[22:16] <jcoxon> my flights are detailed here: http://www.pegasushabproject.org.uk
[22:16] <Fighter1405> Oh you are the guy behing the pegasus launches :)
[22:17] <jcoxon> indeed
[22:17] <Fighter1405> I read those a while back, could have been the first site I read on it all
[22:17] <jcoxon> :-)
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[22:22] <Fighter1405> So you would say that was a good price for the Yaesu?
[22:22] <jcoxon> its a little pricey
[22:22] <Fighter1405> A lot better than all the £400+ radios on ebay
[22:23] <jcoxon> when they do pop up on ebay that yaesu is about 100
[22:23] <Fighter1405> Fair enough, perhaps I'll watch out for them there for a bit first then
[22:23] <jcoxon> yeah
[22:23] <jcoxon> good plan
[22:37] <jcoxon> bbl
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[22:44] Nick change: kingj -> KingJ
[23:13] Nick change: RocketBoy -> RocketBoy|Away
[23:18] DanielRichman (n=DanielRi@78.144.245.8) left irc: "Leaving"
[23:44] RocketBoy|Away (n=Steve@217.47.75.8) left irc: "Leaving"
[23:51] <Laurenceb> hmf my UM12 test hab isnt working
[23:51] <Laurenceb> really wierd - the avr seems to hang
[23:55] jiffe88 (n=jiffe2@209.159.247.189) joined #highaltitude.
[00:00] --- Sun Jun 14 2009