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[05:28] <Akadecca> _johan_: there?
[05:29] <_johan_> Hm?
[05:29] <Akadecca> martin
[05:29] <_johan_> Ah..
[05:30] <_johan_> No private messages?
[05:30] <Akadecca> i'm getting them
[05:30] <_johan_> Ah ok.
[05:30] <Akadecca> something on your end
[05:30] <_johan_> Nope.
[05:31] <_johan_> Nope, as in I dont get them.
[05:31] <_johan_> Go to #megatesting.
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[05:32] <natrium42> leaning IRC? :P
[05:43] Action: akawaka learns the /me command
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[17:22] <natrium42> hey jcoxon
[17:22] Action: natrium42 is trying to find out how much roaming in the north atlantic is for globalstar
[17:23] <natrium42> they don't mention it anywhere on their site
[17:24] <jcoxon> natrium42, oh i think it is pretty good
[17:25] <jcoxon> you planning a transatlantic then?
[17:25] <natrium42> are we not?
[17:25] <jcoxon> oh
[17:25] <jcoxon> this is the conversation from last night
[17:25] <jcoxon> i was sort half around
[17:25] <natrium42> ah
[17:25] <jcoxon> didn't read a lot of it :-D
[17:25] <natrium42> well, i am pretty serious about it :)
[17:26] <jcoxon> so whats the plan then?
[17:26] <natrium42> i have been considering it for a while and the SNOX project gave some inspiration
[17:26] <natrium42> edmoore wants to get a zero pressure balloon, mc- wants to get a 10MHz transmitter
[17:27] <natrium42> and then we can cheaply build 10MHz receivers
[17:27] <natrium42> with software defined radio
[17:27] <natrium42> anyway, i just don't really trust radio, so i was looking at satellite stuff
[17:28] <natrium42> with duplex data, preferably so that we can return pictures in-flight
[17:28] <jcoxon> that would be amazing
[17:28] <jcoxon> what would worry me is that UTARCs near success is due to the cheapness of their payload
[17:28] <natrium42> yep, just inquiring about prices currently
[17:29] <jcoxon> as in they launch, if it fails they just try again
[17:29] <natrium42> satellite could keep working even in water
[17:29] <natrium42> if we conserve power, that could last for months
[17:29] <natrium42> until it washes up somewhere :)
[17:29] <natrium42> that's my dream anyway, no idea how realistic that is
[17:30] <jcoxon> no harm in research
[17:30] <natrium42> gotta look at things first, yeah
[17:30] <jcoxon> let me think
[17:30] <jcoxon> so
[17:30] <jcoxon> Canada to UK?
[17:30] <natrium42> yep
[17:30] <natrium42> or europe
[17:30] <jcoxon> in theory the distance would be about 3500km
[17:30] <natrium42> i assume that it's not too expensive for you to travel to europe if it were necessary
[17:30] <natrium42> i also have some friends there
[17:30] <jcoxon> nah europe wouldn't be a problem
[17:31] <jcoxon> jump on the eurostar
[17:31] <natrium42> or channel tunnel! :P
[17:31] <jcoxon> same thing :-)
[17:31] <jcoxon> now
[17:31] <jcoxon> there is a general shift north of the jetstream as it cross the atlantic
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[17:32] <natrium42> right, what would be the best target date to aim at, you think?
[17:32] <jcoxon> but for example, a launch in 12 hours would in theory make it
[17:32] <jcoxon> that said it would go pretty far north, come down a bit then shoot back over the UK
[17:33] <jcoxon> hmmm, i'm not sure
[17:33] <jcoxon> i haven't really studied the atlantic jetstream
[17:33] <jcoxon> know lots about it over West Africa but i'm not sure that'll help
[17:33] <jcoxon> where abouts would you launch it from?
[17:34] <natrium42> well, i am close to tornto
[17:34] <natrium42> err, toronto
[17:35] <natrium42> but i could travel if need be
[17:35] <jcoxon> UTARC guys are only launching in winter
[17:35] <jcoxon> to take advantage of the stronger jetstream
[17:35] <natrium42> it's just that i have a nice place to launch right near my home
[17:35] <natrium42> and that way i could do a webcast of the launch
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[17:36] <natrium42> hey Laurenceb
[17:36] <Laurenceb> hello
[17:36] <Laurenceb> just been doing flow tests
[17:36] <Laurenceb> very interesting, but I've got a ton of data to interpret
[17:36] <Laurenceb> this is getting tedious :s
[17:36] <natrium42> neato
[17:37] <Laurenceb> I should be able to find collection efficiency as a function of particle size
[17:37] <Laurenceb> it looks about 25%
[17:37] <jcoxon> natrium42, hmmm, would have to therefore enter USA airspace
[17:38] <Laurenceb> I was looking at DDS chips, AD make some nice ones
[17:38] <jcoxon> natrium42, i'll have a look at the jetstream through out the year
[17:38] <jcoxon> bbl
[17:39] <Laurenceb> I dont understand RF power amplifiers properly
[17:39] <natrium42> jcoxon, ok
[17:39] <Laurenceb> but I guess we could copy a design, its not too hard
[17:39] <Laurenceb> theres some cool AD chips, you just put in 16 bit frequency and phase and out it comes :P
[17:41] <natrium42> hehe
[17:41] <natrium42> Laurenceb, i have been looking more at globalstar (and iridium)
[17:42] <natrium42> globalstar actually provides a table of satellite availability for a lat/long coordinate
[17:42] <Laurenceb> ok, I was thinking too expensive
[17:42] <Laurenceb> but maybe not
[17:42] <natrium42> trying to find out about transatlantic roaming charges
[17:42] <Laurenceb> thing is you could make an entire radio based payload for < £100
[17:42] <Laurenceb> but satellite would be a few hundered
[17:42] <natrium42> yah
[17:43] <natrium42> but just looking around atm
[17:43] <natrium42> one way satellite would be pretty cheap
[17:43] <Laurenceb> I dont see why the amplifier output impedance has to match the antenna
[17:44] <Laurenceb> for an rf amp
[17:44] <natrium42> who knows, it's radio :D
[17:45] <Laurenceb> with DC you want a low impedance amp
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[17:46] <Laurenceb> i can see how it will maximise output power
[17:46] <Laurenceb> but not how it maximises efficiency
[17:46] <Laurenceb> as you'll be losing half your power in the tx /
[17:46] <natrium42> perhaps something about resonance?
[17:47] <Laurenceb> I odnt get it...
[17:47] <Laurenceb> hmm do you have firefox running/
[17:47] <natrium42> yes
[17:47] <Laurenceb> what system?
[17:47] <Laurenceb> my firefox has broken
[17:48] <natrium42> ubuntu
[17:48] <Laurenceb> me too
[17:48] <natrium42> but mine isn't messed up :P
[17:48] <Laurenceb> <div> elements dont seem to display correctly
[17:49] <Laurenceb> I'm checking the updates
[17:50] <Laurenceb> I'll restart it
[17:52] <Laurenceb> looking at some of the rf amp designs, quite a few are designed to be resonant, and you excite them with the input
[17:53] <Laurenceb> ah firefox work now :D
[17:53] <Laurenceb> right I'm off before I get locked in the lab overnight
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[17:54] <natrium42> haha
[18:04] <natrium42> jcoxon, self-contained simplex unit with gps --> http://www.globalstar.ca/en/content.php?cid=750#Details
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[18:04] <natrium42> only $199 for a test unit
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[18:22] <Sarge> Hey all
[18:22] <Sarge> When is the next planned launch for FHALP?
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[18:40] <Laurenceb> hello
[18:40] <Laurenceb> horrible weather :(
[18:54] <Laurenceb> http://www.electronicsforu.com/efylinux/circuit/feb2002/cir1.jpg
[18:54] <Laurenceb> c14 and RFC2 form a resonant circuit
[18:54] <Laurenceb> or erm... maybe not
[18:55] <Laurenceb> I can see your putting your rf signal into t2
[18:58] <Laurenceb> hmm ok apparently its not tuned
[19:01] <jcoxon> Laurenceb, ?
[19:01] <Laurenceb> that cicruit I linked
[19:01] <Laurenceb> the output doesnt form a resonant circuit
[19:01] <Laurenceb> its simply class A
[19:02] <jcoxon> OH
[19:04] <Laurenceb> http://www3.interscience.wiley.com/cgi-bin/abstract/114124007/ABSTRACT?CRETRY=1&SRETRY=0
[19:05] <Laurenceb> ^ is interesting, but not sure if everyone on here will be able to view the pdf
[19:05] <jcoxon> they'll need an athens password
[19:05] <Laurenceb> think so
[19:08] <Laurenceb> food time bbl
[19:31] <jcoxon> bbl
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[19:50] <Hiena> Good evening!
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[20:10] <jcoxon> evening mc-
[20:11] <mc-> evening jc
[20:12] <mc-> I've got a 10MHz transmitter design done, kindly given to me by a MIT guy
[20:12] <jcoxon> okay
[20:12] <mc-> 1.8W output
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[20:14] <ai4id> greetings - I was wondering if any of the SNOX guys were here - I have some info about the transmitter after splashdown.
[20:14] <jcoxon> ai4id, nope, sorry
[20:14] <jcoxon> i guess you could email them
[20:15] <ai4id> I think they are swamped with email
[20:15] <jcoxon> did you managed to get some data?
[20:16] <ai4id> not exactly - I've been looking at a waterfall of a recording
[20:17] <Hiena> mc-, what kind of transmitter?
[20:17] <Laurenceb> mc-: interesting :P
[20:17] <ai4id> it looks like during the first 20 seconds of the last transmission, it stopped - burst a few more characters a couple of times - then shorted the transmitter on
[20:17] <Laurenceb> mc-: can you imagebin it?
[20:18] <ai4id> fortunately the flakey crystal provided a distinct signature in the waterfall
[20:18] <jcoxon> ai4id, so is it still detectable
[20:18] <jcoxon> ?
[20:18] <ai4id> the waterfall pattern looks the same as RTTY signal but with only one tone
[20:19] <ai4id> no, I don't thinkso
[20:19] <ai4id> sorry, folks, incredibly I'm new to IRC so I'm not familiar iwth this client
[20:19] <jcoxon> its okay
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[20:20] <ai4id> I doubt it is still on. It looks like it was slowly rising in frequency, as if the batteries were slowly giving out
[20:20] <jcoxon> most clients work the same :-)
[20:20] <Laurenceb> mc-: crystal and transistor based?
[20:20] <jcoxon> ai4id, could that be temperature as well affecting the freq?
[20:20] <ai4id> I am very interested to see a schematic of the transmitter
[20:21] <ai4id> The temp should be quite stable in the ocean
[20:21] <jcoxon> but the change from being in air to ocean?
[20:21] <Laurenceb> hmm my report is due in tomorrow morning :(
[20:22] <mc-> it's a crystal transmitter
[20:22] <ai4id> ahhh, I should explain, I can still see signal over 2 hours and 45 minutes after splashdown, but I would really like a second opinion, that's why I wanted to contact the SNOX team
[20:22] <jcoxon> ai4id, right
[20:22] <mc-> with a classE output, so it's efficient
[20:22] <jcoxon> makes sense now
[20:22] <Laurenceb> mc- cool
[20:22] <ai4id> so the drift downwards is over hours. It could be my TR-7 drifting, though
[20:22] <Laurenceb> mc-: yes, efficiency is the most important thing
[20:24] <jcoxon> ai4id, the SNOX guys are probably sleeping now :-)
[20:24] <Laurenceb> http://imagebin.org/14907
[20:24] <ai4id> anyhow, if any of the team shows up here, please ask them to search for ai4id in their email and call me (my phone # is in their email) so I can get an address to send them my audio files on DVD
[20:25] <Laurenceb> some aerosol deposition tests from this afternoon :p
[20:25] <jcoxon> ai4id, yup no problem, thanks for the info
[20:25] <ai4id> yeah, I was also looking at weather maps and sat images and I think the balloon basically descended into a warm front
[20:26] <ai4id> thanks for the help - this was my first balloon experience, and it has me really interested - hope to be back later
[20:26] <Laurenceb> hmm, hence why I think it needs to be stratospheric
[20:26] <Laurenceb> tropospheric flight is just a pain
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[20:27] <jcoxon> ai4id, cool, it would be nice to make this channel the balloon central
[20:27] <Laurenceb> hey RocketBoy
[20:27] <RocketBoy> yo chaps
[20:27] <Laurenceb> havent tried out the radio yet, too busy
[20:27] <Laurenceb> http://imagebin.org/14907
[20:27] <Laurenceb> been flow testing
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[20:39] <Laurenceb> If I have some antenna impedance, and try to drive it with an amplifier, does the antenna impedance need to match the amp output impedance?
[20:40] <Laurenceb> for maximum power efficiency
[20:40] <rocketboyV1> yes
[20:40] <Laurenceb> why?
[20:40] <rocketboyV1> - if you havn't got a matching circuit
[20:41] <Laurenceb> I'm confused about this, as in the DC case it needs to be a low impedance amplifier
[20:41] <rocketboyV1> its a simple power transfer thing
[20:41] <Laurenceb> I understand about transmission line equations and so on
[20:41] <Laurenceb> but doesnt it mean 50% of your power is wasted in the amplifier?
[20:41] <rocketboyV1> for maximiunm power transfer the sorce and load impedances should be matched
[20:42] <rocketboyV1> nope if your transmitter is 100% efficent and its matched 100% will go into the antenna
[20:42] <Laurenceb> hmm so its like transmission lines
[20:43] <rocketboyV1> it is the same as transmission lines
[20:43] <Laurenceb> it an amplifier output the same as an ac source and impedance?
[20:43] <Laurenceb> or an ac source and a transmission line ?
[20:43] <Laurenceb> ie ideal ac source
[20:44] <rocketboyV1> the impedance of free space is matched to the antenna - then all the power goes into free space
[20:44] <Laurenceb> sure I understand that bit
[20:46] <rocketboyV1> well its a ac souce a transmission line to the antenna - and then antenna - free space (like another lossy transmission line)
[20:46] <mc-> And coax/antennas are around 50 ohm impedance, so you need to match to 50 ohms.
[20:46] <rocketboyV1> then recive antenna transmision line and input impedance of the reciver
[20:47] <Laurenceb> sure
[20:47] <Laurenceb> but the amplifier itself, how can you model that?
[20:48] <Laurenceb> ie if you have some amplifier with output impedance, is the output just ac source + some Z ?
[20:50] <rocketboyV1> So a zero impedance source + a series Z?
[20:51] <Laurenceb> yes
[20:51] <Laurenceb> is that correct?
[20:53] <rocketboyV1> yep -but the power would be measured across the Z
[20:54] <Laurenceb> hang on, the output power?
[20:55] <rocketboyV1> yep
[20:55] <rocketboyV1> ie the voltage across it x the currrnt flowing through it
[20:56] <Laurenceb> right, but isnt that power lost in the tx, or is this like transmission lines in that its the power through it ?
[20:56] <rocketboyV1> power is lost in the TX as heat in the output stage - depending on its efficency
[20:57] <rocketboyV1> so for example a class A amp might achive 30% efficency - i.e. 70% would get lost in heat
[20:57] <rocketboyV1> say a class B might get 50% efficency
[20:58] <rocketboyV1> and class C 75% (25% lost in heat)
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[21:01] <Laurenceb> http://hem.passagen.se/communication/pic/mrf313sch.gif
[21:01] <Laurenceb> ^ thats class C ?
[21:02] <rocketboyV1> yep
[21:03] <Laurenceb> is L5 resonant with C17 and C15 ?
[21:03] <rocketboyV1> Q2 will only be on for a small protion of the input cycle
[21:04] <Laurenceb> so it drives the oscillation?
[21:05] <rocketboyV1> The whole of that output section is a matching section and filter - its 2 pi networks back to back
[21:05] <rocketboyV1> the filter is needed to ensure that the harmonics are minimused - driving the amplifer in class c will case lots of harmonics
[21:06] <akawaka> jesus
[21:06] <akawaka> i know nothing about analog electronics
[21:07] <Laurenceb> wheres the resonant section?
[21:09] <rocketboyV1> Well L5 is likly to be resonant with the impedance presented by C17/C15/L6...
[21:09] <mc-> classE is resonant
[21:10] <mc-> classC doesn't have to be resonant
[21:11] <Laurenceb> right
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[21:11] <rocketboyV1> I thought class E was pulse width modulated to give a sine output
[21:12] <mc-> rocketboyV1 is the guru here, but I think classD is PWM
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[21:14] <Hiena> Seems it's a class C. The last stage's base pulled to the ground.
[21:14] <mc-> http://www.k3pgp.org/Notebook/Wd5cvg/Classetx/classetx.htm
[21:14] <rocketboyV1> In that circuit I'd be surprised if L5 didn't form some part of the output tuned circuit (given its value - WRT to the other inductors)
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[21:16] <rocketboyV1> In some class C output designs you will find a choke instead - its there to provide a DC path to provide power - but high impedance to RF
[21:19] <akawaka> what does a choke do?
[21:19] <mc-> stops RF
[21:19] <Hiena> L5 is a choke coil, keeping the currents in the bay.(Usually high impedance at the working frequencies) The Collins filter will transform the output to the antenna impedance.
[21:21] <Hiena> The L4 is the RF filter blocking the backtalk of the power stage.
[21:23] <natrium42> grr... why are companies so slow to respond to emails? what's the difference to a live phone call...
[21:23] <natrium42> just treat an email like a phone call
[21:23] <mc-> if it was a phone call, it would be engaged...
[21:23] <Hiena> natrium42, because the email is personless.
[21:24] <natrium42> mc-, seen this? http://globalstar.ca/en/content.php?cid=750
[21:24] <natrium42> only $199 and it included gps
[21:24] <natrium42> *includes
[21:25] <natrium42> self contained with battery (though i am sure you could take it apart to make it lighter
[21:25] <natrium42> "Limit one per customer"
[21:26] <rocketboyV1> how much dows it weigh?
[21:30] <natrium42> i requested a datasheet as well as info on reprogramming it
[21:30] <natrium42> will let you know
[21:30] <mc-> you can't reprogram it
[21:30] <natrium42> bl
[21:30] <natrium42> "" Reprogramming available, call Globalstar Customer Care 1.877.728.7466"
[21:30] <mc-> inside it has a STx2 module which is what I've ordered
[21:30] <mc-> I think that means you can configure the update rate?
[21:30] <natrium42> how much was your module?
[21:30] <mc-> module is $99, the dev kit is $600
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[21:30] <natrium42> ok, probably best to do it your way
[21:30] <natrium42> i.e. with stx2 module
[21:30] <natrium42> bbl
[21:41] <mc-> rocketboyV1, isn't the theoretical advantage of FSK over ASK is 3dB?
[21:42] <mc-> so a CW/Morse system would work as well as FSK, by going half the speed?
[21:42] <Laurenceb> why is there an advantage? as you are transmitting all the time?
[21:42] <mc-> so CW would work as well as RTTY if it was half the bit rate?
[21:43] <rocketboyV1> There are all sorts of advantages with different modulation schemes - some depentant on the coding scheme you put over them
[21:44] <rocketboyV1> There is loads about the the net about modulation and encoding scheme gains
[21:45] <Laurenceb> wikipedia is good for the basics
[21:45] <rocketboyV1> In general the more the gain the more the complex the modulation/cosding scheme
[21:45] <rocketboyV1> coding
[21:46] <mc-> after hearing Snox yesterday, I think CW was working better than RTTY
[21:46] <rocketboyV1> so for example - you might choose a simple modulatuion scheme to keep the hardware development down - and use a complex coding scheme to recover some of the lost advantage
[21:47] <Laurenceb> mc-: but it was biffent power and baudrate
[21:47] <Laurenceb> different*
[21:47] <mc-> many RTTY frames were lost, but the CW frames were almost always usable
[21:48] <mc-> I think it was the same power (RTTY and CW)?
[21:48] <Laurenceb> hmm any latex users?
[21:48] <rocketboyV1> (not that I'd own up)
[21:49] <Laurenceb> whats the differnece between [htp] and [h!] ?
[21:49] <Laurenceb> \begin{table}[htp] as opposed to \begin{table}[h!]
[21:49] <rocketboyV1> no - idea that was a off colour joke
[21:50] <Laurenceb> hmm my images have gone mad
[21:50] <Laurenceb> they are floating everywhere
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[22:18] <Laurenceb> http://imagebin.org/14910
[22:18] <Laurenceb> interesting
[22:18] <Laurenceb> thats with the HV turned on/off
[22:20] <Laurenceb> efficiency seems to change a bit with size... need to write some code to make an efficiency graph
[22:35] <Laurenceb> whats the equivalent of ctrl -alt -del in linux?
[22:36] <Laurenceb> ps -x ?
[22:36] <rocketboyV1> kill
[22:37] <Laurenceb> prprocess id?
[22:37] <rocketboyV1> ps lists process status
[22:37] <rocketboyV1> think so
[22:38] <Laurenceb> phew
[22:38] <Laurenceb> gnuplot went mad for a minute there
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[23:32] <jcoxon> damn it
[23:32] <jcoxon> this new GM862 module isn't responding
[23:33] <natrium42> to what?
[23:33] <natrium42> what does the LED show?
[23:33] <jcoxon> any serial data i send
[23:33] <jcoxon> the LED is flashing like normal
[23:34] <jcoxon> and my voltage shifter Tx and Rx lights up when i send commands
[23:34] <jcoxon> but i see nothing
[23:34] <jcoxon> if i swap to the GM862-GPS everything works
[23:34] <natrium42> is Tx and Rx connected the right way?
[23:34] <natrium42> ah
[23:34] <natrium42> try cleaning the connector
[23:35] <akawaka> ttl serial?
[23:36] <natrium42> cmos
[23:36] <jcoxon> might be something to do with the autobauding
[23:36] <jcoxon> as i didn't set the baud rate
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[23:37] <jcoxon> but i can't seem to find the baudrate if its changed
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[23:41] <jcoxon> hmmmm it seems to echo every command
[23:41] <jcoxon> as in the lights echo
[23:41] <jcoxon> rather than the console
[23:46] <jcoxon> the problem is that it actually worked last night
[23:46] <jcoxon> which means that i've managed to break it
[23:46] <jcoxon> though i have no idea how
[23:46] <natrium42> i also get echo on my computer when one of the serial lines is unconnected
[23:46] <natrium42> it's pretty weird
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[23:47] <jcoxon> grrr
[23:53] <Laurenceb> its probably unrelated, but I had the same problem with my phone
[23:53] <Laurenceb> a reboot and an "AT&F" was needed
[23:54] <RocketBoy> have you guys ever thought about building a super-pressure balloon?
[23:55] <jcoxon> i've thought about it
[23:55] <Laurenceb> I have
[23:55] <jcoxon> not really sure the praticalities
[23:55] <Laurenceb> its *hard*
[23:56] <Laurenceb> we'd need a barn or something
[23:56] <Laurenceb> to set up a production area
[23:56] <Laurenceb> and it would have to be really well organised
[23:57] <Laurenceb> as in "quality control" and cleanliness
[23:57] <jcoxon> what could be achieved from a superpressure balloon
[23:57] <Laurenceb> very long duration
[23:57] <RocketBoy> round the world flight
[23:57] <Laurenceb> I think MIR balloons are more practical
[23:57] <Laurenceb> but again its very hard
[23:57] <natrium42> RocketBoy, so a dirigible basically?
[23:58] <Laurenceb> not exactly, spherical for a start, google it
[23:58] <RocketBoy> there is a lot of effort goinging into pumpkin shaped Sp balllons by NASA
[23:59] <jcoxon> if we were clever we could launch from scotland and get it into the polar vortex
[23:59] <RocketBoy> so not dirigible
[23:59] <jcoxon> spin it round the N pole and get it down into canda
[23:59] <jcoxon> canada*
[00:00] --- Fri Mar 14 2008