highaltitude.log.20080310

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[01:11] Action: Laurenceb_ has finished :P
[01:12] <Laurenceb_> right time to do some printing :D
[01:41] <akawaka> recover your stuff or redid it?
[02:06] <Laurenceb_> redid it
[02:07] <Laurenceb_> well not just the old work, I've finished everythngi I need to do this weekend now :P
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[16:55] <edmoore> hi jcoxon
[16:55] <edmoore> yeah, saw that canon thing
[16:55] <edmoore> also notice the auto-balloon-seperation whatsit
[16:55] <edmoore> ingenious
[16:56] <jcoxon> they are sooo much more advanced then us
[16:56] <edmoore> they're all retired hams
[16:56] <edmoore> they have experience and time and money and more of them :)
[16:56] <jcoxon> indeed
[16:56] <jcoxon> UTARC are planning to launch tomorrow
[16:57] <edmoore> cool - what are they launching?
[16:57] <jcoxon> to take advantage of the mean ass jet stream
[16:57] <jcoxon> zero pressure, trans atlantic
[16:58] <edmoore> woweee
[16:58] <edmoore> yeah it's pretty fierce
[16:59] <jcoxon> http://www.spiritofknoxville.com/
[17:00] <edmoore> how far back is edt?
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[17:01] <jcoxon> its 0200UTC launch
[17:01] <edmoore> are we that atm?
[17:02] <jcoxon> ummmmmm
[17:02] <jcoxon> are we in daylight savings
[17:02] <jcoxon> yeah we must be
[17:02] <jcoxon> so no we're not
[17:02] <jcoxon> we must be UTC + 1
[17:03] <jcoxon> oh wait
[17:03] <jcoxon> we aren't in daylight saving
[17:03] <jcoxon> so we are UTC
[17:03] <jcoxon> haha
[17:03] <edmoore> i stayed up for atv yesterday
[17:04] <jcoxon> :-)
[17:04] <jcoxon> apparently its a little broken
[17:04] <jcoxon> but is going to be fine
[17:04] <jcoxon> ATV that is
[17:04] <edmoore> oh?
[17:04] <edmoore> in what way is it broken?
[17:06] <jcoxon> http://news.bbc.co.uk/1/hi/sci/tech/7287417.stm
[17:10] <edmoore> redundancy eh
[17:11] <edmoore> working on some software so the badgerworks flight computer can talk to another one about everything, so we can have full redundancy
[17:11] <edmoore> gps + coms
[17:12] <jcoxon> a sort of 'bus' then?
[17:13] <edmoore> well, we've got a few to choose from
[17:13] <edmoore> will probs be over i2c if we go for a sort of loose coupling
[17:14] <jcoxon> oh right okay
[17:14] <edmoore> and spi if we want them talking more and comparing calculations and stuff
[17:14] <edmoore> they'll double-check each other on critical stuff at any rate
[17:14] <jcoxon> cool
[17:14] <jcoxon> i'm going to put together my radio beacon this afternoon
[17:14] <edmoore> we really need three so we can have a majority
[17:15] <edmoore> the decision is - if one goes down do you try and continue the mission or do you go to an abort
[17:15] <edmoore> not an issue for passive payloads but one for guided payloads
[17:16] <jcoxon> you mean like the shuttle's 5 'puters
[17:19] <jcoxon> right i'll bbl
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[18:08] <jcoxon> oooo didn't realise there is a shuttle launch tomorrow
[18:08] <jcoxon> tis a bumper time for space
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[18:13] <Hiena> Good evening!
[18:13] <jcoxon> evening Hiena
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[18:20] <edmoore> yo again jcoxon
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[18:41] <jatkins> hi all
[18:42] <jcoxon> hey jatkins
[18:42] <jcoxon> hows teh payload coming along?
[18:43] <jatkins> good, thanks
[18:43] <jatkins> I met mc- yesterday
[18:43] <jatkins> he came over to my house and helped me with the gps and stuff
[18:43] <jatkins> I'll have the gps talking to the arduino by the end of today :)
[18:44] <jcoxon> oooo cool that you met mc-
[18:44] <jcoxon> excellent about the GPS
[18:44] <jatkins> yep
[18:44] <jcoxon> what else is left?
[18:44] <jatkins> radio
[18:45] <jatkins> wanted to ask about that..
[18:45] <jcoxon> you having a phone?
[18:45] <jatkins> nope
[18:45] <jcoxon> okay
[18:45] <jatkins> just 434MHz
[18:45] <jcoxon> okay
[18:45] <jatkins> I've been reading on the wiki about the Nova 1 radio communications
[18:45] <jcoxon> (might be a good idea to do your first flight piggy backing another payload)
[18:45] <jcoxon> right
[18:45] <jatkins> maybe, I'm still thinking about that
[18:46] <jatkins> I think they used http://www.radiometrix.co.uk/products/ntx2nrx2.htm
[18:46] <jcoxon> yup
[18:46] <jatkins> ok
[18:46] <jcoxon> its the best radio
[18:46] <jatkins> okay, cool
[18:46] <edmoore> seconded
[18:46] <jcoxon> jatkins, the big question is what you are going to put into the radio
[18:46] <jcoxon> there are 2 options really
[18:46] <jatkins> telemetry, i.e. plain text
[18:46] <jcoxon> morse or rtty
[18:46] <jcoxon> so rtty
[18:46] <jatkins> rtty
[18:46] <jcoxon> right
[18:47] <jcoxon> now thats where it gets complicated
[18:47] <jatkins> ah
[18:47] <jatkins> I'll just be transmitting numbers
[18:47] <jcoxon> yup but those numbers are encoded in a particular way
[18:47] <jatkins> parsing the NMEA data down to lon., lat., and velocity
[18:47] <jcoxon> yeah
[18:47] <jatkins> I've seen the data in hyperterminal
[18:48] <jatkins> I'll just write a parser on the arduino
[18:48] <jatkins> is morse code a better option?
[18:48] <jcoxon> no i understand
[18:48] <jcoxon> but if you feed that data directly into the radio it won't be rtty and won't have a great range
[18:48] <jcoxon> (am i right in thinking that edmoore
[18:48] <jcoxon> )
[18:48] <jcoxon> ?
[18:48] <jatkins> ok
[18:48] <jcoxon> morse is simpler
[18:49] <jcoxon> but slower
[18:49] <jatkins> ok
[18:49] <jcoxon> in theory rtty is the best option but requires considerable work to get properly working
[18:49] <edmoore> yes correct
[18:49] <jatkins> here's an example of what I want to downlink: 5114800>00032681
[18:49] <edmoore> jatkins, radio is one of the trickiest bits to this game
[18:49] <jatkins> ok
[18:49] <jatkins> I can substitute > for -1 or something though
[18:49] <jatkins> to keep it just to numbers
[18:49] <edmoore> there's a fundamental limit (called the shannon limit) to how much you can fit down a communications channel
[18:50] <jcoxon> now rocketboy and laurence have developed radio systems which you just pass the data into and it does the work for you
[18:50] <jatkins> ok
[18:50] <edmoore> for wire this is huge, no need to worry about it (although it's becomign a problem with gigabit speeds on long network cables) but for the low power radio links we use, it is a problem
[18:50] <jatkins> ok
[18:51] <edmoore> essentially, you can increase the range of a radio by slowing down the data you feed into it
[18:51] <edmoore> so each bit lasts longer
[18:51] <jatkins> ok
[18:51] <edmoore> the normal stuff you've seen in hyperterminal is coming in at presumably 9600bps
[18:51] <jatkins> yep
[18:51] <jatkins> but that is fed to the arduino, and then parsed?
[18:52] <edmoore> we're currently using 30bps for the radio we're developing
[18:52] <jatkins> I won't feed directly from the gps
[18:52] <edmoore> big difference
[18:52] <jatkins> ok
[18:52] <jatkins> lol
[18:52] <edmoore> yeah, so the simplest way is to feed it morse code pulses that you can decode by ear
[18:52] <jcoxon> jatkins, now morse
[18:52] <jcoxon> actually don't do morse
[18:52] <jcoxon> instead pulse the number
[18:52] <jcoxon> so for the number 5 it does 'dit' 'dit' 'dit' 'dit' 'dit'
[18:52] <jatkins> ok
[18:53] <jcoxon> this can be done purely on a gpio
[18:53] <edmoore> could you make 5 = dar
[18:53] <edmoore> roman numeral stylee?
[18:53] <jcoxon> edmoore, i've been thinking about this
[18:53] <jcoxon> i really think the best way is pure 'dit's for numbers
[18:53] <jatkins> i.e. use the gpio as an input and detect HIGH or LOW?
[18:53] <jcoxon> i means that multiple peple can decode
[18:53] <jatkins> maybe send low to separate numbers?
[18:53] <jcoxon> jatkins, no use it as an output
[18:53] <jatkins> ok
[18:53] <jcoxon> bring it high for 1 sec say as a dit
[18:54] <jcoxon> then 1 sec low
[18:54] <jatkins> ok
[18:54] <jcoxon> then have 3 secs low in between numbers
[18:54] <jatkins> ok
[18:54] <jcoxon> directly attach the gpio to the radio datain
[18:54] <jatkins> so this is a microcontroller on the ground outputting?
[18:54] <jatkins> or in the balloon
[18:54] <jatkins> ?
[18:55] <jcoxon> this from the flight computer on the ground
[18:55] <edmoore> the balloon does this. on the ground you have the radio and your ears
[18:55] <jatkins> km
[18:55] <jatkins> ok*
[18:55] <edmoore> no, the flight computer on the balloon, i think jcoxon means
[18:55] <jcoxon> oops
[18:55] <jcoxon> sorry
[18:55] <jcoxon> i've got to dash now
[18:56] <jatkins> ok, cya
[18:56] <jatkins> thanks
[18:56] <jatkins> so the flight computer is outputting to the transmitter?
[18:56] <edmoore> yes
[18:56] <jatkins> ok
[18:57] <edmoore> and the transmitter turns the highs and lows from the flight computer into radio waves
[18:57] <jatkins> ok
[18:57] <jatkins> once the data's fed to the transmitter, is it easier from then on?
[18:57] <edmoore> and transmits them. the ground radio picks them up and turns them into (demodulates them into) audio tones
[18:57] <jatkins> yep, ok
[18:57] <edmoore> once you've put the data into the transmitter, that does the rest
[18:57] <jatkins> ok, cool
[18:57] <edmoore> you just have to make an aerial
[18:58] <jatkins> yep
[18:58] <jatkins> yagi?
[18:58] <jatkins> sorry
[18:58] <jatkins> I got confused..
[18:58] <jatkins> the transmitter doesn't come with one?
[19:02] <edmoore> sorry, went to the loo
[19:02] <jatkins> np
[19:02] <edmoore> ok, antennas are a funny business, but you don't really need to understand them all that well to use them
[19:02] <jatkins> ok
[19:02] <edmoore> essentially we are in this situation
[19:03] <edmoore> we have limited transmitter power
[19:03] <jatkins> ok
[19:03] <edmoore> we can slow the baud rate down to get more range
[19:03] <jatkins> ok
[19:03] <edmoore> another technique is to use a high directional antenna to focus all the transmitter enegery to the receiver
[19:03] <jatkins> http://tinyurl.com/34zd98
[19:03] <jatkins> 30bps is 1 kb/5 minutes
[19:04] <edmoore> correct!
[19:04] <jatkins> kilobyte*
[19:04] <jatkins> ok
[19:04] <edmoore> however, the balloon is swinging around a lot, and we can't really control where it's pointing
[19:04] <jatkins> I guess you have to be accurate with the maths on a directional antenna?
[19:04] <edmoore> so we use a transmitter which transmits all over
[19:04] <jatkins> i.e. the angle to point it in
[19:04] <jatkins> omnidirectional?
[19:05] <edmoore> well, we use one which has a 'radiation pattern' which is sort of a 45 degree cone downwards
[19:05] <edmoore> yeah, fairly omnidirectional
[19:05] <edmoore> we stop it transmitting up into the sky as we'll alwats be below the payload
[19:05] <edmoore> otherwise, it's prettyy much omnidirectional
[19:05] <edmoore> so we have to use the transmitter
[19:05] <jatkins> ok
[19:05] <edmoore> but we can use a high direcvtional receiver antenna as we can point it at the balloon on the ground
[19:06] <jatkins> ok
[19:06] <edmoore> so we use a 'yagi' (a high gain, very directional antenna) on the receiver
[19:06] <jatkins> oh .. the omnidirectional is on the balloon?
[19:07] <edmoore> yes
[19:07] <jatkins> oh right
[19:07] <edmoore> correct
[19:07] <edmoore> right, need to go right now
[19:07] <jatkins> I though you just had an antenna
[19:07] <jatkins> ok
[19:07] <jatkins> just one thing
[19:07] <jatkins> http://www.radiometrix.co.uk/products/ntx2nrx2.htm
[19:08] <edmoore> nope, you need an antenna to transmit and receive
[19:08] <edmoore> will talk more soon
[19:08] <jatkins> it says usable range 0.5km?
[19:08] <jatkins> don't worry now
[19:08] <jatkins> cya
[19:08] <edmoore> yes, but that is at a much higher baud rate
[19:08] <jatkins> oh, ok, got it
[19:08] <jatkins> thanks
[19:08] <edmoore> so if you half the baud rate, you double the range
[19:08] <jatkins> ok
[19:08] <edmoore> ok, cya later
[19:09] <jatkins> bye
[19:09] <jatkins> thanks
[19:09] Action: jatkins is going for tea
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[19:17] <laurence_> hi all
[19:17] Nick change: laurence_ -> Laurenceb_
[19:17] <edmoore> yo
[19:18] <Laurenceb_> I just discovered the target lenght for reports in 10 pages, not 5
[19:18] Action: Laurenceb_ gets typing
[19:18] <edmoore> interim?
[19:18] <Laurenceb_> what do you mean?
[19:18] <edmoore> what report?
[19:18] <Laurenceb_> mphys project
[19:18] <edmoore> 10 pages for a masters?
[19:19] <edmoore> surely nearer 50 would be more appropriate?
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[19:19] <Laurenceb_> yes, + appendices and references
[19:19] <edmoore> christ
[19:19] <edmoore> standards dropping in the other place :p
[19:19] <Laurenceb_> its supposed to be of a quality that could be submitted to a journal
[19:20] <Laurenceb_> hence the length limit
[19:20] <akawaka> double space
[19:20] <Laurenceb_> ha, there is a latex document class we have to use
[19:21] <akawaka> damnit!
[19:21] <Laurenceb_> my temperature sensor doesnt work :( I spent ages making up a new one, and it seems to be faulty
[19:21] <akawaka> so my little fitpc box can only encode 320x200 video at about 10fps
[19:21] <Laurenceb_> doesnt make sense :( I was working on an antistatic workbench
[19:22] <Laurenceb_> anyone know a good thermocouple IC that would work instead?
[19:22] <Laurenceb_> they are so expensive its crazy
[19:25] <edmoore> what range?
[19:25] <Laurenceb_> -50 to 20 C
[19:25] <Laurenceb_> balloon range :P
[19:26] <Laurenceb_> I might be able to get something from stores, but failing that I'll send off an order tomorrow
[19:27] <edmoore> analog sample some spi 10bit ones
[19:28] <Laurenceb_> yes, but analogue would be easier to interface with the existing setup
[19:28] <Laurenceb_> and farnell dont seem to stock them, I need it by wednesday am
[19:29] <edmoore> if it's a2d, just use a bloody thermistor
[19:29] <Laurenceb_> accuracy?
[19:29] <edmoore> calibrate it and hope for the best
[19:29] <Laurenceb_> hmm havent got time to do that...
[19:30] <Laurenceb_> but I guess it could be done later
[19:30] <Laurenceb_> I'll have a look to see if we have some already in stores tomorrow morning
[19:32] <Laurenceb_> I need to write litre/second in latex, but litres^-1 looks confusing... any ideas?
[19:33] <edmoore> what?
[19:34] <Laurenceb_> hmm maybe just litre/second
[19:34] <edmoore> so you want:
[19:34] <edmoore> l s (-1)<- superscript
[19:34] <edmoore> ?
[19:34] <Laurenceb_> yes
[19:35] <Laurenceb_> I dont know... see what it reads like
[19:35] <edmoore> well just liek usual
[19:36] <edmoore> l s$_{-1}
[19:36] <edmoore> sorry, s/_/^
[19:36] <Laurenceb_> yep
[19:37] <Laurenceb_> but just l isnt very clear, you dont know what it is as it appears a bit out of context
[19:38] <edmoore> litres s$^{-1}
[19:38] <edmoore> maybe
[19:40] <akawaka> linux from scratch is a slow and not very exciting process
[19:41] <edmoore> I've decided to learn it by installing uCLinux
[19:41] <edmoore> and working up from the bottom
[19:42] <edmoore> got a blackfin board it can probably go on
[19:42] <edmoore> analog blackfin cpu/dsps are really very impressive
[19:42] <edmoore> I'm very very inpressed with them
[19:44] <akawaka> url?
[19:44] <akawaka> i'm following this: http://www.linuxfromscratch.org/
[19:45] <edmoore> type blackfin linux
[19:45] <edmoore> that looks awesome
[19:45] <edmoore> well i'm being less hardcore by using uclinux which is smaller
[19:46] <akawaka> if you can stand to look at yourself in the mirror in the morning then i guess thats okay
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[19:50] <Laurenceb_> ?
[19:50] <Laurenceb_> what
[19:50] <Laurenceb_> anyone here use the dia diagram editor?
[19:53] <edmoore> nope
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[20:05] <fnoble> edmoore: oi!
[20:05] <edmoore> yo
[20:05] <fnoble> check your email
[20:05] <fnoble> texting you back wasnt working
[20:06] <edmoore> yes no problem
[20:06] <edmoore> weather jsut got crap too
[20:06] <edmoore> just*
[20:06] <fnoble> yeah sucks
[20:06] <Laurenceb_> its not too bad here
[20:06] <Laurenceb_> maybe its passed over in your direction :p
[20:07] <fnoble> so, do you want to pub?
[20:09] <edmoore> no
[20:09] <edmoore> weather is bollocks
[20:10] <fnoble> ok, cool
[20:10] <edmoore> if i was in town, maybe
[20:10] <fnoble> any more thoughts on the mmc card?
[20:11] <edmoore> not really on the spi level front
[20:11] <edmoore> although i can't try it on hardware
[20:18] <edmoore> you?
[20:20] <edmoore> fnoble:
[20:20] <edmoore> ping
[20:20] <edmoore> etc
[20:20] <fnoble> erm, not really, tried it in mode 0
[20:20] <fnoble> no joy
[20:20] <fnoble> tried it with a lower clock speed, still nothing
[20:21] <fnoble> running out of ideas to try
[20:21] <edmoore> it's got to be something
[20:29] <edmoore> ^ helpful comment du jour
[20:29] <jatkins> edmoore: I just got my gps talking to my arduino with rs-232
[20:30] <edmoore> awesome, nice one jatkins
[20:30] <edmoore> you know what time it is now?
[20:30] <jatkins> mc explained some stuff to me yesterday
[20:30] <jatkins> from the gps?
[20:30] <edmoore> yeah why not :)
[20:30] <jatkins> ah, haven't written a parser yet
[20:30] <jatkins> just got the rs-232 working
[20:30] <edmoore> exactly, that's the fun bit
[20:30] <jatkins> i.e. I'm getting all the numbers coming in
[20:30] <jatkins> lol
[20:31] <jatkins> I'll need to look at it in hyperterminal again to decode the nmea
[20:31] <jatkins> btw, I had a look at this: http://www.rfsolutions.co.uk/acatalog/Smart_Radio_Transmitter_Receiver_Module.html
[20:32] <jatkins> would I be correct in thinking I could get 64 bps from 30 km?
[20:32] <edmoore> probably - how did you work it out?
[20:32] <jatkins> 30,000 / 100
[20:32] <jatkins> so how many times further than its normal range
[20:32] <edmoore> ok
[20:32] <jatkins> then 192,000 bps / 300
[20:32] <edmoore> well my rule isn't a hard and fast one
[20:33] <edmoore> but 64bps sounds like a fair number
[20:33] <jatkins> ok
[20:33] <jatkins> ah, it's 192,00
[20:33] <edmoore> the radiometrix ones will do that too
[20:33] <jatkins> no, that's right
[20:33] <jatkins> ok
[20:33] <edmoore> we've had 300 working fine at several hundred km
[20:33] <jatkins> but I think you can do this one via rs-232
[20:33] <jatkins> 300 meters usual range?
[20:33] <edmoore> but we have other tricks to squeeze range out, like pulse shaping. but you have to do degree maths to figure out why that works :P
[20:34] <jatkins> lol
[20:34] <edmoore> well rs232 isn't that great a protocol at such low speeds
[20:34] <jatkins> ok
[20:34] <jatkins> oh
[20:34] <jatkins> I was assuming 192,00 bps was the transmission rate?
[20:34] <jatkins> "Host Interface up to 19200 Baud"
[20:35] <edmoore> that's right
[20:35] <edmoore> yep
[20:35] <jatkins> ok
[20:35] <jatkins> do you think that would be an easier option for me as i'm a beginner?
[20:36] <jatkins> rather than using gpios
[20:36] <edmoore> using the serial port?
[20:36] <jatkins> yeah
[20:36] <edmoore> i don't think it'll go slow enough
[20:36] <edmoore> like you say, you need to be around 64bps. i don't think most serial ports would let you go that low
[20:37] <edmoore> without writing your own software serial port, which would be more difficult
[20:37] <edmoore> i honestly thing morse would be the easiest way
[20:37] <jatkins> oh, sorry, I think I was a bit confusing: I thought 64 bps was the baud for data transmission to the ground, not the rs-232 speed
[20:37] <edmoore> the 'host interface' is more simple that you imagine
[20:37] <edmoore> it litterally transmits what you put in
[20:38] <jatkins> ok
[20:38] <jatkins> but is host interface the speed between the arduino and radio or speed between transmitter and receiver?
[20:38] <jatkins> (on the ground)
[20:38] <edmoore> the upper limit it gives will be one where they can probably guarantee it working at 300m
[20:38] <jatkins> ok
[20:38] <edmoore> both
[20:38] <jatkins> ok
[20:38] <edmoore> the transmitter just turns the electrical pulses of the arduino into radio waves
[20:38] <jatkins> ok
[20:39] <jatkins> is that what an oscillator does - create radio waves?
[20:39] <edmoore> but it's still all at the same speed
[20:39] <jatkins> ok
[20:39] <edmoore> yes
[20:39] <jatkins> oh right, ok
[20:39] <edmoore> do you know how to work out wavelength?
[20:39] <natrium42> hey edmoore * jatkins
[20:39] <jatkins> no
[20:39] <natrium42> *=&
[20:39] <jatkins> hi
[20:39] <natrium42> how goes project, jatkins ?
[20:40] <edmoore> hi natrium42
[20:40] <edmoore> fnoble: I'm stumped. anyway to ensure there's data in the sector?
[20:40] <jatkins> good, thanks
[20:40] <jatkins> just interfaced the gps with the arduino
[20:40] <fnoble> yeah, thats what using dd proved
[20:40] <jatkins> did camera shutter a while ago
[20:41] <fnoble> dd dumps raw data from the disk
[20:41] <edmoore> yeah thought so
[20:41] <natrium42> jatkins, cool, looks like you are moving forward well
[20:41] <edmoore> arse
[20:42] <jatkins> yep
[20:42] <jatkins> I met mc yesterday
[20:42] <jatkins> he helped a lot
[20:43] <jatkins> and he built a hot-wire cutdown for me
[20:43] <jatkins> - resistor + transistor + power supply
[20:44] <edmoore> fnoble: there's a bus from queens on the hour
[20:44] <edmoore> I can drive you back (cider will have worn off by then)
[20:44] <edmoore> and there's the option of chinese at about 10
[20:44] <fnoble> dont think i will come up
[20:44] <fnoble> sorry
[20:45] <fnoble> tired and hungry and have to meet someone in about an hour
[20:45] <edmoore> you sound like a lady of the night fallen on hard times
[20:46] <natrium42> jatkins, yah, i wasn't so sure about your magnetic cutdown suggestion (although it was pretty interesting)
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[20:46] <natrium42> bah
[20:46] <fnoble> only im not getting paid for the meeting
[20:46] <edmoore> he took that well....
[20:46] <fnoble> but basically,yes
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[20:46] <fnoble> ok, must venture into the cold and rain, wish me luck
[20:47] <natrium42> [16:46] <natrium42> jatkins, yah, i wasn't so sure about your magnetic cutdown suggestion (although it was pretty interesting)
[20:47] <fnoble> bye
[20:47] <edmoore> good luck
[20:49] <natrium42> cold & rain? pfft, england...
[20:49] <jatkins> ok
[20:49] <jatkins> lol
[20:50] <jatkins> it's actually not raining where I am
[20:50] <jatkins> was earlier
[20:50] <jatkins> cya fnoble
[20:50] <natrium42> here we have mountains of snow
[20:50] <natrium42> it snowed pretty badly on the weekend, most traffic was halted
[20:51] <jatkins> we get it once a year [if] we're lucky
[20:51] <jatkins> whole country goes into hiding if we get snow :)
[20:51] <natrium42> haha
[20:51] <natrium42> well, you don't have the infrastructure to deal with snow
[20:52] <natrium42> i.e. snow plows standing by
[20:52] <jatkins> yeah
[20:52] <jatkins> schools close, no complaining from me
[20:52] <natrium42> lol
[20:53] <natrium42> shuttle launch tonight \o/
[20:53] <natrium42> well, it's tomorrow morning for you
[20:53] <edmoore> yep
[20:53] <edmoore> and utarc launch tomorrow morning (for us)
[20:53] <natrium42> oh, neat
[20:53] <natrium42> i need to setup my tracker again :P
[20:54] <jatkins> yup
[20:54] <jatkins> 6:20 gmt I think
[20:54] <jatkins> (shuttle)
[20:54] <natrium42> should move my personal site to that dedicated server i got
[20:55] <jatkins> dedicated server - cool
[20:55] <jatkins> who's your host?
[20:55] <natrium42> liquidweb.com
[20:55] <jatkins> ok
[20:56] <natrium42> that server is $174/month
[20:56] <jatkins> I'll have a look
[20:56] <jatkins> what's the specs?
[20:56] <natrium42> quite $$$, but it's good for business
[20:56] <jatkins> yeah
[20:56] <natrium42> https://www.liquidweb.com/cart/content/dedicated/Webmaster/Plan1/
[20:56] <jatkins> ok
[20:57] <natrium42> i only moved my business site to it so far
[20:57] <natrium42> now it's much zippier :D
[20:57] <jatkins> :)
[20:57] <jatkins> I need to get a dedicated server eventually, I'm building a hosted wiki app
[20:58] <natrium42> ah
[20:58] <natrium42> perhaps VPS is sufficient?
[20:58] <jatkins> that's pretty good price
[20:58] <jatkins> yeah, probably
[20:58] <jatkins> virtual private server?
[20:58] <natrium42> for what's included it's very good
[20:58] <natrium42> yep
[20:58] <jatkins> isn't that the same as dedicated - your server, they maintain it?
[20:59] <jatkins> well their server, which you're paying to use all for yourself?
[20:59] <natrium42> VPS -- you get a fraction of the computers CPU/network
[20:59] <natrium42> and memory
[20:59] <jatkins> oh right
[20:59] <jatkins> ok, cool
[20:59] <natrium42> dedicated -- you get a whole computer
[20:59] <jatkins> ok
[20:59] <jatkins> I've g2g now, good talking to you
[21:00] <natrium42> see ya
[21:00] <jatkins> ..I'll be up early for the shuttle tomorrow :D
[21:00] <natrium42> hehe :)
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[21:00] <natrium42> edmoore, when's your rocket launching?
[21:00] <edmoore> october in theory
[21:01] <edmoore> still a tonne of stuff to do
[21:04] <edmoore> we've a more normal one that's ready to launch now, tho
[21:04] <edmoore> but that's not from a balloon
[21:04] <natrium42> hopefully your payload doesn't weigh one tonne :)
[21:04] <natrium42> cool
[21:07] <edmoore> :p
[21:07] <edmoore> still lots of questions
[21:08] <edmoore> like where to deploy the chutes
[21:09] <natrium42> oh you mean whether to wait until it reaches denser atmosphere?
[21:09] <edmoore> yeah
[21:10] <edmoore> i mean if you look at the dynamic pressure vs time simulations, there's a big spike at boost, then that decays to 0
[21:10] <edmoore> it's 0 for a whole load of time
[21:10] <edmoore> then picks up again at about 40km altitude
[21:10] <edmoore> as it's coming back in
[21:10] <natrium42> right
[21:10] <edmoore> so you'd think you could do it just as dynamic pressure starts to pick up
[21:11] <edmoore> as it'll deploy quite nicely then, in theiry - not too much of a yank, but enough for it to actually deploy
[21:11] <edmoore> but then you're doing mach4 at that point
[21:11] <edmoore> at chutes don't work at mach4
[21:11] <edmoore> so you've gotta wait really
[21:11] <natrium42> what about a pilot chute?
[21:12] <edmoore> it'll still be desperately, almost destructively unstable at mach4
[21:12] <edmoore> you've gotta wait till you go subsonic, really
[21:12] <edmoore> during which time there are various nasties, like a peak stagnation temperature of 850+ degrees celcius
[21:14] <edmoore> i think it'll be ok if we deploy really late, as the rocket has such a high mass fraction of fuel, it'll be just an empty carbon fibre tube when it comes back in, so it should be slow enough balistically at 1km to deploy the chute well enough. I *hope*
[21:14] <edmoore> we've only got a 200g budget for the entire recovery system
[21:14] <edmoore> which is another drawback against dual deployment
[21:15] <edmoore> that's problem #129 anyway :) lots of things to iron out
[21:16] <natrium42> hehe
[21:16] <Hiena> edmoore, how abbout the long wire brake?
[21:16] <natrium42> yeah
[21:16] <natrium42> but it's fun
[21:17] <edmoore> yeah - it's the project I've been waiting 20 years for :)
[21:17] <Hiena> It's weights nothing, reliable.
[21:17] <edmoore> Hiena - it's just a question of deploying that wire
[21:18] <edmoore> i mean it may come to that, but i reckon if we can get away with just letting it pass through the hideous super and transonic region, then we should
[21:18] <natrium42> edmoore, you are 20 y/o??
[21:18] <edmoore> well, 21 just turned
[21:18] <natrium42> ah, cool
[21:19] <edmoore> hence having no idea really what I'm doing with any of this stuff. which is the bit I like most :)
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[21:22] <edmoore> oooh 19 people
[21:22] <edmoore> tho laurence always ruins it by counting as 2 :p
[21:23] <Hiena> Maybe, he is working some ESA cloning project.
[21:24] <edmoore> the atv is pretty cool
[21:24] <edmoore> I love how overkill it is for the job at hand
[21:24] <natrium42> hehe
[21:24] <edmoore> but correspondingly a hop away from being human-capable
[21:24] <natrium42> they are having a problem with it today though :/
[21:24] <edmoore> yeah
[21:25] <edmoore> lost a propulsion circuit
[21:25] <edmoore> guess that's why they have redundant ones!
[21:25] <natrium42> :)
[21:25] <Hiena> How they could lost it?
[21:25] <edmoore> I hate the fact that we can't communicate with our payloads. really need to sort that out
[21:25] <edmoore> I'd really like to make a decision about whether or not to cut-down/deploy main/whatever, rather than trying to code for every failure eventuality
[21:26] <edmoore> well, it stopped working
[21:26] <edmoore> it has 4 propulsion circuits, it can run on 3 and carry on, and it can run on two in theory but they'd proabbly ditch it
[21:26] <natrium42> Hiena, http://spaceflightnow.com/ariane/v181/080309prop.html
[21:27] <edmoore> that's an amazing quote
[21:27] <Hiena> I means i usually lost sandwiches, coke bottles, hats when i'm flying, but not a main systems. Well, once i left a muffler, but it was a different situation.
[21:27] <edmoore> "There is an off-nominal situation"
[21:30] <Hiena> "The issue could be due to an electronic fault or a problem within a maze of propellant and helium gas lines ..."
[21:30] <Hiena> Maze? What the hell? French design?
[21:31] <edmoore> I think the propulsion was developed just down the road from me in the UK, at EADS Astrium :s
[21:32] <Hiena> Usually a rocket engine consist a dozen of fuel lines. Hardly to call as maze, compaired to an average hydraulics system.
[21:35] <akawaka> for some reason i knew this spacecraft would have problems
[21:37] <edmoore> wyzat?
[21:38] <Hiena> Insider information?
[21:41] <Hiena> Btw, at the weeken i found a nice nozzle material for a small rocket engine. Tube for the brake lines. The stailess steel ones could withstand 260 bar.
[21:41] <edmoore> wow
[21:42] <edmoore> have you grocked aeroconnsystems?
[21:43] <akawaka> i would imagine all the connections for 28 small thrusters would create quiet a maze
[21:47] <Hiena> Yeah, i'm just reading the study about this spaceship. Insane....
[21:48] <edmoore> do you have a link?
[21:51] <Hiena> http://64.233.183.104/search?q=cache:-UVzsjnpqT0J:www.unexplained-mysteries.com/forum/lofiversion/index.php/t72298.html+Jules+Verne+ESA+spaceship+specification+28+thruster&hl=hu&ct=clnk&cd=1&gl=hu&client=firefox-a
[21:53] <Laurenceb_> unexplained-mysteries.com ?!
[21:53] <akawaka> it shoots lasers!
[21:53] <Laurenceb_> haha
[21:56] <Hiena> Yup. The datas looks reliable, and it's source too (Arianespace Mission Updates).
[21:57] <Hiena> Sometimes, you could digg up information from the stragest places.
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[22:02] <Laurenceb_> http://imagebin.org/14785
[22:03] <Laurenceb_> ^ my ioniser tronics
[22:06] <Laurenceb_> I used dia, could you use eagle to do something like that?
[22:08] <akawaka> ccfl inverter?
[22:09] <Laurenceb_> cold cathode flourescent light
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[22:13] jgw (n=jgw@unaffiliated/jgw) returned to #highaltitude.
[22:17] <Laurenceb_> bbl
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[22:34] <edmoore> natrium42: what's the best way to get your head around linux - just download and start playing?
[22:34] <natrium42> yes, i would say so
[22:35] <natrium42> it has become very user friendly recently
[22:36] <Laurenceb_> even I can use it
[22:37] <Laurenceb_> so much better than windows :P
[22:37] <edmoore> i mean i want to use it in a non-user-firendly way
[22:37] <edmoore> i.e. *understand* it
[22:37] <Laurenceb_> embedded linux?
[22:38] <edmoore> well i reason that might be a good way, but i don't actually have any clue
[22:38] <Laurenceb_> get an NGW100 :P
[22:38] <edmoore> lol
[22:38] <natrium42> edmoore, you can always drop down to command line
[22:38] <natrium42> and play around with scripting
[22:39] <natrium42> because scripting is what linux is about :P
[22:39] <edmoore> yeah. I just quite want to use it in embedded stuff, but unless i really know what's going on I fear I might break it without realising
[22:39] <Laurenceb_> I havent broken my NGW100 yet, and I compiled my own kernel for it
[22:39] <edmoore> interesting software thingamy: http://www.youtube.com/watch?v=kYUrqdUyEpI
[22:39] <edmoore> have a looksee at that
[22:40] <Laurenceb_> ha
[22:40] <edmoore> know what caused it?
[22:40] <edmoore> no looking up :p
[22:40] <edmoore> you have to guess based on the video
[22:41] <Laurenceb_> integer overflow
[22:41] <Laurenceb_> or something
[22:41] <edmoore> you knew that already, tart :p
[22:41] <edmoore> but yeah
[22:41] <edmoore> float to int
[22:41] <edmoore> this is why i fear putting linux on a parafoil. stakes are much lower, but unless i kind of *understand* it, i fear it
[22:41] <Laurenceb_> of course I knew that
[22:41] <Laurenceb_> yes
[22:42] <edmoore> as it's not a pre-deployed chute, i want to be surew the software will be there to do the deploying
[22:42] <Laurenceb_> hmm maybe I should stick my rogallo hardware on a parafoil
[22:43] <edmoore> i'm having 2 identical copies of the flight computer
[22:43] <Laurenceb_> the cortex m3 ?
[22:43] <edmoore> lpc21248
[22:43] <edmoore> 2148*
[22:43] <Laurenceb_> which is cortex m3 - arm right?
[22:44] <edmoore> arm7tdmi-s
[22:44] <Laurenceb_> year
[22:44] <edmoore> it's the new arm core, yeah
[22:44] <edmoore> would go with it, but only goes up to 128k
[22:44] <edmoore> the lpc has 512
[22:44] <edmoore> tho I want to go blackfin as it's a real beast
[22:44] <Laurenceb_> yes, its amazing
[22:44] <edmoore> could do all the imu stuff and everything else
[22:44] <edmoore> it could do everything
[22:45] <edmoore> fnoble would kill me if he saw this
[22:45] <edmoore> it's the running joke that i'm too distracted by new and sexy processors
[22:45] <Laurenceb_> but linux is a good way to handle things
[22:45] <edmoore> but it is damn nice
[22:45] <edmoore> 1000mips for 40mA
[22:45] <Laurenceb_> wow
[22:45] <edmoore> i'd rather go for something lighter that i can comprehend I think
[22:45] <Laurenceb_> when you have lots of power
[22:45] <edmoore> like TNKernal
[22:45] <Laurenceb_> AVR :P
[22:45] <edmoore> we're using that on the single board flight computer. it's nice
[22:46] <Laurenceb_> I've yet to be limited by it
[22:46] <edmoore> by linux?
[22:46] <Laurenceb_> avr
[22:46] <edmoore> i was on the imu
[22:46] <Laurenceb_> but for an imu arm7 would be better
[22:46] <edmoore> and i don't think it could do all of our big-but-boring stuff aswell as the actual flight computer stuff
[22:46] <edmoore> like usb and fat32
[22:47] <Laurenceb_> atmels tools make the avr32 really easy to work with
[22:47] <edmoore> that takes up space and cpu, much more so than the critical stuff
[22:47] <edmoore> yeah, it does look nice
[22:47] <edmoore> does it have MMU?
[22:47] <edmoore> i guess so if it runs full kernel
[22:48] <Laurenceb_> well
[22:48] <Laurenceb_> I installed uClinux
[22:48] <edmoore> oh ok
[22:48] <Laurenceb_> but I'm just looking it up
[22:48] <edmoore> how do you find it?
[22:48] <edmoore> also, ahve you worked out how much stack something uses?
[22:48] <Laurenceb_> http://avr32linux.org/twiki/bin/view
[22:49] <Laurenceb_> http://www.atmel.com/dyn/resources/prod_documents/doc32047.pdf
[22:50] <edmoore> Laurenceb: we also have an avr board for tits-up
[22:50] <edmoore> deploys the main chute at 200m altitude, come what may
[22:50] <Laurenceb_> ok
[22:51] <edmoore> seperate pyros, batts, entirely self contained
[22:51] <Laurenceb_> sorry I was wrong, I didnt install uclinux
[22:51] <Laurenceb_> but the full version
[22:51] <edmoore> so it does have an mmu?
[22:51] <Laurenceb_> yep
[22:51] <edmoore> i guess that question is self-answering
[22:52] <Laurenceb_> follow the second link
[22:53] <Laurenceb_> if you dont mind windows, avr32 studio is useful
[22:53] <Laurenceb_> problem is the avr32 is bga
[22:54] <edmoore> i'm going to attempt an oven
[22:54] <edmoore> as the blackfin is too
[22:54] <edmoore> tho it comes in lqfp flavours
[22:54] <edmoore> but pretty vast ones
[22:54] <Laurenceb_> I'm worried about vibration
[22:54] <edmoore> shouldn't be too much on yours, surely?
[22:54] <Laurenceb_> and stress, on a rocket
[22:54] <edmoore> it's not like it's a rocket
[22:55] <Laurenceb_> why dont you just get on with it and build your rocket ?
[22:55] <Laurenceb_> :P
[22:55] <edmoore> ... we are
[22:55] <edmoore> doing it daily
[22:55] <edmoore> and i'm doing the imu sim in simulink right now
[22:55] <Laurenceb_> so stop the other projects
[22:55] <Laurenceb_> cool
[22:55] <edmoore> which ones?
[22:56] <Laurenceb_> like this parafoil
[22:56] <edmoore> the parafoil is an awesome project
[22:56] <Laurenceb_> and balloon board
[22:56] <Laurenceb_> true
[22:56] <edmoore> the balloon board is for the gondola laurence
[22:56] <edmoore> that's why we developed it
[22:56] <Laurenceb_> ok
[22:56] <edmoore> engage brain before using mouth
[22:56] <Laurenceb_> I guess its all coming together
[22:57] <edmoore> and the parafoil is a nice test of the imu is spacelike conditions, in anger, but not as dangerous as a rocket
[22:57] <Laurenceb_> I could work on a radio for you if your interested
[22:57] <edmoore> well we've sent the pcbs off for our radio module
[22:58] <edmoore> but havn't finalised the code proper yet
[22:58] <Laurenceb_> been planning to for a while
[22:58] <Laurenceb_> avr or pic?
[22:58] <edmoore> avr
[22:58] <Laurenceb_> cool, which one
[22:58] <edmoore> we're using bpsk, rather than fsk
[22:58] <edmoore> ]just an 78
[22:58] <edmoore> 8*
[22:58] <edmoore> atmega8
[22:58] <Laurenceb_> right
[22:58] <edmoore> note much code going in it
[22:58] <edmoore> not*
[22:58] <Laurenceb_> how do you do bpsk?
[22:59] <Laurenceb_> delay lines?
[22:59] <edmoore> well we're using the bpsk standard that hams use
[22:59] <edmoore> so you psk on the audio
[22:59] <edmoore> but feed it into an fm transmitter
[22:59] <Laurenceb_> oh god
[22:59] <edmoore> but it still works a lot better than vanilla fsk
[22:59] <Laurenceb_> that doesnt sound like a good plan to me
[22:59] <edmoore> it's proven good
[22:59] <Laurenceb_> :S
[22:59] <Laurenceb_> hmm
[22:59] <edmoore> it's the standard for beacons hams use
[22:59] <Laurenceb_> not sith 10mw
[23:00] <edmoore> yes with 10mW
[23:00] <edmoore> it's much better than an equivalent fsk system for a given power
[23:00] <Laurenceb_> what scanner?
[23:00] <edmoore> yaesu
[23:00] <edmoore> as ever
[23:00] <Laurenceb_> ok
[23:00] <edmoore> brb
[23:01] <Laurenceb_> you do understand the difference between rf bpsk and audio modulated rf carrying bpsk?
[23:01] <Laurenceb_> and why the former is far superior
[23:03] <Laurenceb_> well, unless you write custom software and use a ssb scanner.. but that would be silly
[23:03] <edmoore> yes of course
[23:03] <edmoore> laurence let's not have this conversation
[23:04] <edmoore> i've done my research
[23:04] <edmoore> there are a million psk31 decoder programs
[23:04] <edmoore> it's a standard
[23:04] <edmoore> it was written to replace rtty fsk for hams
[23:04] <edmoore> it's totally established
[23:04] <edmoore> next?
[23:04] <Laurenceb_> where is your descriminator?
[23:05] <Laurenceb_> in the scanner?
[23:07] <Laurenceb_> ok, I'll explain my plan: use bfsk at 4kbps to send data at 1024 bits per second. each second you send a 128 byte packet of data
[23:08] <Laurenceb_> the data is spread x4 with a pseudo random code
[23:08] <Laurenceb_> recieved using ssb ---> sound card
[23:09] <Laurenceb_> each 128 byte packet has 128 7 bit characters, each with a parity bit. and reed solomon encoded
[23:10] <Laurenceb_> range should be as good as with RTTY over similar hardware
[23:12] <Laurenceb_> sorry to start an argument :P
[23:13] <akawaka> you've sent the ham radio world into tormoil
[23:13] <Laurenceb_> hehe
[23:15] <Laurenceb_> akawaka: do you have any radio experience?
[23:16] <edmoore> why is bpsk your plan?
[23:16] <edmoore> i thought you were working on fsk?
[23:17] <Laurenceb_> yes
[23:17] <Laurenceb_> sorry
[23:17] <akawaka> laurenceb_: i passed my ham exam on saturday
[23:17] <akawaka> hopefully i'll have my license by wednesday
[23:17] <akawaka> so ask me again on friday
[23:17] <Laurenceb_> the thing is you want to keep things digital wherever possible
[23:18] <Laurenceb_> using a scanner as part of the decoding system is a bad idea
[23:18] <edmoore> what makes you say that, and where am I not?
[23:18] <Laurenceb_> using SSB to downconvert is the best plan
[23:18] <akawaka> its a balance between doing things correct and getting things done
[23:18] <Laurenceb_> if you use a commercial module, you can only do fm
[23:19] <Laurenceb_> unless you treak the fm deviation such that its phase shift
[23:19] <Laurenceb_> tweak*
[23:19] <Laurenceb_> I havent investigated that yet
[23:20] <edmoore> it's not really possible
[23:20] <edmoore> you can generate your own fm quite easily, but you'd need to get the resulting thing licensed
[23:20] <edmoore> psk31 has the advantage of not needing that
[23:20] <Laurenceb_> yes
[23:20] <Laurenceb_> so your decoding audio
[23:20] <Laurenceb_> but how do you get the audio?
[23:20] <edmoore> yep
[23:21] <edmoore> through fm
[23:21] <edmoore> we're not using a vco on the tx
[23:21] <edmoore> just encoding straight onto carrier
[23:21] <Laurenceb_> what decodes the fm to audio?
[23:22] <edmoore> an fm receiver?
[23:22] <Laurenceb_> so your reciever is decoding it?
[23:22] <edmoore> to audio, yes
[23:22] <Laurenceb_> this is what I'm getting at
[23:22] <Laurenceb_> thats bad news
[23:22] <Laurenceb_> you discriminator introduces lots of noise
[23:23] <edmoore> it's fine within the tech available, and better than what we've been using
[23:23] <Laurenceb_> you want to do that in soltware
[23:23] <Laurenceb_> in theory the ramp filter technique is sub optimal
[23:24] <akawaka> doesn't it have the advantage of not having to modify the receiver though?
[23:24] <edmoore> if i cared about optimality, i'd build it all myself with ldpc and proper bpsk
[23:24] <Laurenceb_> hmm
[23:24] <edmoore> what i care about is making something better than the rtty fsk we've been using to date
[23:24] <Laurenceb_> well I'm sticking with rtty + reed solomon
[23:24] <edmoore> using the same receiving hardware we've been using
[23:24] <edmoore> cos it's a nice receiver
[23:25] <edmoore> yep, which I belive suffers from the same disadvantages you just described of ours, plus some other ones
[23:25] <akawaka> what do you have?
[23:25] <edmoore> a yaesu transceiver which is really quite sensitive. RocketBoy sold it on to us, and it's what we've always used.
[23:26] <Laurenceb_> edmoore: RTTY is as digital as you can get
[23:26] <Laurenceb_> all the signal processing is in the pc
[23:26] <edmoore> i thought the pc gets fed an audio signal whose freq is shifted
[23:26] <edmoore> which is same as ours, except the phase is shifted
[23:26] <Laurenceb_> no no no
[23:27] <Laurenceb_> the pc is fed the raw rf
[23:27] <Laurenceb_> downconverted to audio range
[23:27] <edmoore> oh I see - how are you downconverting?
[23:27] <Laurenceb_> using a mistuned ssb scanner
[23:27] <Laurenceb_> thats why it has such a good range for the power
[23:27] <Laurenceb_> doh
[23:28] <Laurenceb_> :P
[23:29] <Laurenceb_> still there ?
[23:30] <edmoore> yep, just trying to figure this out with some maths
[23:30] <Laurenceb_> hehe
[23:31] <Laurenceb_> have you spoken to henry
[23:31] <edmoore> nope
[23:31] <edmoore> not for ages
[23:31] <Laurenceb_> he worked on a radio for UKHAS1, but it was a bit glitchy so we had to drop it
[23:31] <edmoore> it works now
[23:31] <Laurenceb_> I'm sure he has some good software
[23:31] <edmoore> but it was just what you've built
[23:32] <edmoore> serial > rtty at 50 baud or 300 baud, 16level shaping
[23:32] <Laurenceb_> I use 256 levels
[23:33] <edmoore> the joys of 8bit pwm, eh
[23:33] <Laurenceb_> yep
[23:33] <Laurenceb_> do you understand how FM recievers work?
[23:33] <Laurenceb_> ie the descriminator stage
[23:33] <edmoore> yup
[23:34] <Laurenceb_> that can be done better using FFT
[23:34] <edmoore> sure
[23:35] <Laurenceb_> and effecively truetty (or fldigi) does it in software
[23:35] <Laurenceb_> you remember the NOVA flight that used the technique you describe?
[23:36] <Laurenceb_> it had about 30Km range only
[23:36] <edmoore> so what are you doing that's different to what we've been doing with truetty?
[23:37] <Laurenceb_> forward error correction, and "spread spectrum"
[23:37] <edmoore> cos we've had 300km at 300baud with no problem off shaped rtty and truetty
[23:37] <Laurenceb_> I use the "" as its only 4X spread
[23:37] <Laurenceb_> yes, but low data rate
[23:37] <Laurenceb_> I think 1024 baud is possible
[23:37] <edmoore> well, 300 baud with no attemt at correction
[23:38] <edmoore> just raw data
[23:38] <Laurenceb_> rtty suffers from framing errors
[23:38] <Laurenceb_> spread spectrum solves that
[23:38] <edmoore> i see what you mean now
[23:39] <Laurenceb_> and also there is no need for start and stop bits
[23:39] <Laurenceb_> or tune up pulses
[23:40] <edmoore> so no reconstruction envelope
[23:40] <Laurenceb_> a corrupted rtty stop/start can screw up an entire packet
[23:41] <Laurenceb_> but the basic "physical layer" is good
[23:42] <edmoore> so what filter is used to extract the info from the fft?
[23:43] <Laurenceb_> just the difference of two passbands
[23:43] <Laurenceb_> ie you fft will be synced to the data
[23:43] <Laurenceb_> so one time bin is one bit long
[23:44] <edmoore> i'll be back online in 3 mins - need to go to room
[23:44] edmoore (n=edmoore@chu-gw.churchillcambridge.co.uk) left irc:
[23:51] edmoore (n=edmoore@pomegranate.chu.cam.ac.uk) joined #highaltitude.
[23:51] <edmoore> back
[23:52] <Laurenceb_> hey
[23:52] <Laurenceb_> ok then ideally logic one is some frequency bin n
[23:52] <Laurenceb_> logic zero will be n-1 (or n+1)
[23:53] <Laurenceb_> you have three FFT filters running
[23:53] <Laurenceb_> the advanced one is 1/2 a bit ahead, the retarded one is 1/2 behind
[23:54] <Laurenceb_> the centered one is used to give the data
[23:54] <Laurenceb_> the despread output signal strength from the others os compared
[23:54] <Laurenceb_> and sampling rate increased or decreased
[23:55] <edmoore> as a function of
[23:55] <edmoore> ?
[23:55] <Laurenceb_> its very standard all this, none of its my idea
[23:55] <Laurenceb_> usually integral
[23:55] <Laurenceb_> you can look it all up
[23:55] <edmoore> i'd like to read some papers or similar, yeah
[23:55] <edmoore> got any links?
[23:56] <Laurenceb_> gimme 5
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[23:58] <fnoble> hello
[23:58] <Laurenceb_> this is good - http://www.tapr.org/ss_g1pvz.html
[23:59] <Laurenceb_> a bit old school, but reading the explanations of the operating principle explained with a working system is good
[00:00] --- Tue Mar 11 2008