highaltitude.log.20090318

[00:00] <Laurenceb> maybe if you went in at night with a quadcopter and a disguised payload
[00:00] <shellevil> if you act like a biologic
[00:00] <shellevil> and they don't care enough
[00:01] <shellevil> are they really going to scrub at t-1 minute if a bird comes along and sits on the ET
[00:02] <Ferris-Wheel> heh
[00:03] <natrium42> Laurenceb, yeah 1D model
[00:04] <Laurenceb> what shape is the envelope?
[00:04] <natrium42> teardrop
[00:04] <Laurenceb> ah good
[00:04] <natrium42> well, not perfect teardrop
[00:04] <natrium42> plastic will flutter around
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[00:05] <Laurenceb> I'd guesstimate 0.3 to 0.4
[00:06] <Laurenceb> http://en.wikipedia.org/wiki/Drag_coefficient
[00:09] <natrium42> sounds reasonable
[00:09] <Laurenceb> but its so hard to be precise
[00:10] <Laurenceb> it should be more aerodynamic in ascent than descent
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[00:11] <hallam> lo
[00:12] <edmoore> lo
[00:12] <Laurenceb> hi hallam
[00:13] <natrium42> lo
[00:13] <Laurenceb> natrium42: I think I have a solution
[00:13] <natrium42> i feel so lonely
[00:13] <Laurenceb> you can calculate the coefficient on the fly
[00:13] <natrium42> Laurenceb, how?
[00:13] <Laurenceb> natrium42: would you like me to cuddle you?
[00:14] <Laurenceb> :P
[00:14] <natrium42> Laurenceb, i though hallam & edmoore started that soldg by police
[00:14] <natrium42> *song
[00:14] <Laurenceb> using data on how ballast drops affect descent rate
[00:15] <natrium42> ah, provided we can estimate those
[00:15] <Laurenceb> use an extended kalman filter
[00:16] <natrium42> i knew you would say that :(
[00:16] <Laurenceb> you have some coefficient you want to estimate
[00:16] <Laurenceb> you have an initial estiamte
[00:16] <Laurenceb> but its very high error
[00:16] <Laurenceb> you have noisy meaassurements
[00:17] <Laurenceb> theres only one solution to this problem
[00:17] <natrium42> :P
[00:17] <Laurenceb> if we wrent venting helium you could simplify it to delta_v=k*t_drop
[00:18] <Laurenceb> where t_drop is solenoid valve on time
[00:18] <Laurenceb> unfortunately we vent helium so the envelope deflates
[00:18] <Laurenceb> but its only a bit more complex
[00:18] <Laurenceb> we can find the fractional change in envelope radius
[00:19] <Laurenceb> using the ballast level sensor
[00:22] <Laurenceb> which isnt too good...
[00:22] <Laurenceb> you might want to average it over an hour or so
[00:23] <Laurenceb> but the good news is we dont need a hugely accurate estimate of ballast level
[00:25] <Laurenceb> as you drop ballast, your error on k will decrease
[00:25] <Laurenceb> if you havent dropped for a while, error will start to increase
[00:26] <Laurenceb> so you contatantly increase the error on k and adjust k using an hour long rolling average of measured ballast level
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[00:27] <Laurenceb> during a drop you start of with small amounts - based on the size of the error on k, then increase the drops as you gain a better understanding of the behaviour. Stopping when you start ascending
[00:30] <Laurenceb> actually using the lvel sensor is unnesassary - as ballast drops will occur in bursts around sunset local time, and helium venting around midday to mid afternoon, so using a level sensor serves no purpose. May as well use the k value from the previous evening with error added to account to helium venting that day
[00:30] <Laurenceb> sorry this si turning into a monologue
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[00:41] <Laurenceb> so... ok... this is basically what I think, extended kalman filter to estimate k using observations f change in descent rate with each drop. Each day we increase our uncertainty on k by some amount and also increase k to account for the venting of helium
[00:58] <Laurenceb> natrium42: ping
[01:02] <natrium42> sorry, just working on the test launch
[01:02] <natrium42> not sure i can make tomorrow
[01:02] <natrium42> weather outlook isn't great either
[01:02] <Laurenceb> ?
[01:03] <Laurenceb> test launch? on a tether?
[01:03] <natrium42> nope, latex balloon
[01:03] <natrium42> flight computer & spot test
[01:03] <Laurenceb> ah cool
[01:07] <Ferris-Wheel> hehe latex
[01:07] Action: Ferris-Wheel makes immature jokes
[01:09] <Laurenceb> grow up
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[01:10] Action: SpeedEvil wishes you could easily linux http://www.ebuyer.com/product/146672
[01:15] <Laurenceb> natrium42: what gps are you using?
[01:16] <natrium42> venus
[01:17] <Laurenceb> ah ok
[01:17] <Laurenceb> with the old firmware?
[01:17] <natrium42> yes
[01:18] <natrium42> also have the gm862-gps for backup
[01:18] <Laurenceb> ok
[01:18] <Laurenceb> with gsm?
[01:19] <natrium42> yep
[01:19] <Laurenceb> neat, we have a lot of hardware
[01:19] <Laurenceb> hope we dont crash in the sea :-/
[02:20] <SpeedEvil> Laurenceb what was that TI tranciever chip?
[02:21] <Laurenceb> CC1100
[02:21] <SpeedEvil> ah yes, thanks.
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[02:26] <Laurenceb> SpeedEvil: you can use trhe etiny modules
[02:30] <Laurenceb> setting it up looks fairly compex, but thats because its so powerful :P
[02:30] <Laurenceb> bascially an AX25 packet transponder in an IC
[02:30] <SpeedEvil> yeah - they seem to have a configurator, but...
[02:30] <Laurenceb> you mant to be able to do it with a uC
[02:31] <Laurenceb> I'm presently insatlling google earth 5 on ubuntu 64 bit
[02:31] <Laurenceb> seems to be working... almost
[02:33] <Laurenceb> linux has Ax25 support built in
[02:34] <Laurenceb> but it expects to be talking to a TNC, and I think that IC has more built in than a tnc
[02:34] <Laurenceb> may take some hacking to connect it as an AX25 port in linux
[02:35] <Laurenceb> but... if you could you could connect to the net through a balloon mesh network :D
[02:36] <Laurenceb> probably eaiest to use a uC to make it behave like a TNC, as you're going to need a uC anyway to connect it to your machine
[02:36] <Laurenceb> put it in a usb dongle :D
[02:38] <Laurenceb> you could also use it as a APRS transmitter
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[07:14] <natrium__> hi
[07:15] <natrium__> halo3 launch moved to thursday or friday
[07:15] <natrium__> Laurenceb, when are you launching?
[07:16] <Laurenceb> friday
[07:16] <natrium__> hmm, should i launch thursday then?
[07:19] <Laurenceb> dont mind
[07:24] <jcoxon> hey natrium__
[07:24] <jcoxon> i'm not really going to be around thurs or fri at the times you suggested
[07:27] <jcoxon> but definitely go ahead with the flight
[07:35] <jcoxon> ping natrium, there might be a HF launch in the US by Bill Brown on Friday
[07:39] <natrium__> ok
[07:39] <natrium__> looks like it's best to launch on thursday then
[07:40] <jcoxon> natrium__, i'd go for what ever was safest and easiest
[07:40] <jcoxon> someone will be around to check the streams
[07:43] <jcoxon> yay we got onto google
[07:45] <natrium__> orly?
[07:47] <natrium__> neato
[07:51] <Laurenceb> yo
[07:52] <Laurenceb> neat
[07:52] <Laurenceb> yeah you only need to google atlantic halo
[07:52] Action: natrium__ is driving the tracker crazy atm
[07:54] <jcoxon> natrium__, the new tracker is great
[07:54] <jcoxon> with the ability to expand all the points :-D
[07:54] <natrium__> :)
[07:55] <jcoxon> Laurenceb, did you get the sensor in the post? can't remember if you told me or not
[07:57] <Laurenceb> yep
[07:57] <natrium__> so, there's going to be ustream and those static photos each 5 mins, i think
[07:57] <Laurenceb> photos?
[07:58] <natrium__> yeah, i will demonstrate
[07:58] <natrium__> http://spacenear.us/tracker/
[07:58] <Laurenceb> just a sec
[07:58] <Laurenceb> playing with kml atm
[07:58] <natrium__> ok
[07:58] <natrium__> let me know when to start it
[08:02] <jcoxon> cya all
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[08:02] <Laurenceb> go for it
[08:04] <natrium__> anyway, you get the point
[08:05] <natrium__> going to be slower at the launch though
[08:08] <Laurenceb> ah ok
[08:08] <Laurenceb> thats what the top bit is for
[08:08] <Laurenceb> how often are they downlinked?
[08:08] <Laurenceb> and how?
[08:09] <natrium__> right now i set the delay to 10 seconds
[08:10] <Laurenceb> how are they downlinked?
[08:10] <natrium__> an example on uploading pics is here --> http://wiki.ukhas.org.uk/projects:tracker
[08:10] <natrium__> just using curl
[08:10] <Laurenceb> sure, but from the payload
[08:10] <natrium__> oh, for the test launch it's going to be a ground camera
[08:11] <natrium__> :P
[08:11] <natrium__> seconds transatlantic launch will have image downlink via iridium
[08:12] <Laurenceb> oh this flight?
[08:13] <Laurenceb> thought we werent flying iridium
[08:13] <Laurenceb> I've got to head off, cya
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[08:14] <natrium__> this flight is spot
[08:14] <natrium__> hi rjharrison
[08:14] <rjharrison> hi natrium42
[08:14] <rjharrison> opps :
[08:14] <Laurenceb> cya
[08:14] <rjharrison> Is there talk of a launch this w/e ?
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[08:17] <natrium__> i am launching on thursday
[08:26] <rjharrison> Cool
[08:26] <rjharrison> Testing the envelope? Is there a time ?
[08:27] <natrium__> testing flight computer and SPOT. envelope is a KCI 1200
[08:27] <natrium__> thursday 1400GMT i think
[08:28] <natrium__> going to have a webcast, so you have to be here :P
[08:28] <rjharrison> great, I'm assuming just track on space near us
[08:28] <natrium__> yep
[08:28] <rjharrison> cool I'll be there
[08:28] <natrium__> track, webcast and ground photos
[08:28] <natrium__> excellent
[08:28] <natrium__> i should get some sleep, 4:30 am again :(
[08:28] <natrium__> g'nite
[08:29] <rjharrison> This will be the first time I have seen you use your tracker
[08:29] <rjharrison> nights
[08:29] <natrium__> hehe, yeah, i never used it myself
[08:29] <natrium__> mobile data used to be damn expensive in canada
[08:29] Action: natrium__ Zzz
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[08:41] <Laurenceb> hello
[09:11] <Laurenceb> hmm just looked over some data...
[09:12] <Laurenceb> if the rogallo is launched on friday, you need a glide ratio of around 3.5 to reach EARS
[09:12] <Laurenceb> tests varies between 3.4 and 4
[09:12] <Laurenceb> if I've got it trimmed right it should just reach ears
[09:12] <Laurenceb> but its touch and go
[09:14] <Laurenceb> its interesting how little difference there was between my really badly trimmed tests and well trimmed ones... it seemed very big to the naked eye, but actually its only 20%
[09:22] <Ferris-Wheel> 20% is quite a bit O.o
[09:23] <Laurenceb> yeah but if you get most airframes that out of trim its going to cause a lot more issues
[09:23] <Laurenceb> than 20% decrease in lift/drag
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[09:55] <shellevil> how testing?
[10:17] <Laurenceb> testing?
[10:18] <shellevil> its interesting how little difference there was between my really badly trimmed tests and well trimmed ones... it seemed very big to the naked eye, but actually its only 20%
[10:18] <Laurenceb> oh launching down a hill
[10:18] <shellevil> ah
[10:19] <Laurenceb> then using get a map to work out how well it glided
[10:19] <Laurenceb> I did it ages ago
[10:19] <Laurenceb> plot launch and landing locations then find the distance with the help of gimp
[10:26] Action: Laurenceb is wondering how to do internet over cc1100
[10:28] <Laurenceb> whats the difference between TCP and IP packets?
[10:31] <Laurenceb> ok... wikipedia has the answers
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[10:34] <Laurenceb> shellevil: knowledgable on this?
[10:35] <shellevil> nnot really tcp runs over IP as I understand it
[10:36] <Laurenceb> yeah sure
[10:36] <Laurenceb> ok... looks fairly simple
[10:36] <shellevil> you need packet loss well under 50% for consistent performance
[10:36] <Laurenceb> TCP controls ports, IP ip addresses
[10:36] <Laurenceb> yeah
[10:36] <shellevil> and packet delays under a few minutes
[10:36] <shellevil> other than that, it should 'just work'.
[10:36] <Laurenceb> wondering if you could send TCP IP directly over CC1100
[10:37] <shellevil> Actually
[10:37] <Laurenceb> looks possible but you would have to do packet fragmentation
[10:37] <Laurenceb> not sure how to do it in software
[10:37] <shellevil> the maximum self-generated packet size is 64 bytes isn't it
[10:37] <Laurenceb> max is 255
[10:37] <shellevil> I mean the internal buffers
[10:37] <Laurenceb> for the cc1100
[10:37] <shellevil> otherwise you have to clock out while recieving
[10:37] <Laurenceb> cant remember
[10:37] <shellevil> which does bad things to the SNR
[10:38] <Laurenceb> yeah 64
[10:39] <shellevil> 64 would mean horrible things - IIRC the header is still 32 bytes for a fragment
[10:39] <shellevil> well - bad - not that horrible
[10:39] <Laurenceb> Im not sure its even allowed
[10:39] <Laurenceb> hmm where does it say it decreases the SNR in the datasheet
[10:40] <Laurenceb> oh ok.. minimum IPv4 is 20 bytes
[10:40] <shellevil> 68 bytes is minimum general MTU
[10:41] <Laurenceb> MTU?
[10:41] <shellevil> http://valerieaurora.org/tcpip.html
[10:41] <shellevil> maximum transmit unit
[10:41] <shellevil> the maximum packet length a link can have
[10:41] <shellevil> however, you can do stuff like van-jacobsen header compression, and drop it way down
[10:42] <Laurenceb> groo
[10:42] <Laurenceb> how would I do this..?
[10:42] <shellevil> it may well be simpler to - if you want to maintain the SNR - simply chop up packets
[10:43] <Laurenceb> what? at a low level?
[10:43] <shellevil> yeha
[10:43] <Laurenceb> hmm ok
[10:43] <Laurenceb> so just take raw IP datastream and stick it into packets?
[10:43] <shellevil> once you reassemble the packets on the other end, it's only the timing when they come out that varies
[10:43] <shellevil> pretty much
[10:44] <Laurenceb> maybe sink to packet headers so each IP packet is an integer number of sub packets
[10:45] <shellevil> also
[10:46] <shellevil> looking at the PPP and SLIP RFCs may be of use
[10:46] <Laurenceb> whats that?
[10:46] <shellevil> ways of framing IP datagrams over modem links
[10:46] <Laurenceb> ok
[10:46] <shellevil> and the VJ header compression over PPP
[10:47] <Laurenceb> how would I impliment this?
[10:47] <Laurenceb> hardware would look somithing like -serial - spi - CC1100
[10:48] <Laurenceb> so I'd have some driver reading and writing commands to the CC110 to send packets
[10:48] <shellevil> what's the other side?
[10:48] <Laurenceb> linux pc
[10:48] <shellevil> oh - in that case, don't bother
[10:48] <shellevil> make it look like a transparent serial link
[10:48] <Laurenceb> hmm
[10:48] <shellevil> connect it up as serial, and point pppd at it
[10:48] <Laurenceb> pppd?
[10:49] <Laurenceb> ah ip through serial?
[10:49] <SpeedEvil> yes
[10:49] <Laurenceb> nice
[10:50] <SpeedEvil> pppd is the generic ip-over-serial solution
[10:50] <SpeedEvil> used for many things - from ADSL to GPRS to simple modems
[10:50] <Laurenceb> hmm... can you identify IP headers in the stream?
[10:50] <SpeedEvil> from memory, yes, it doesn't encode them, it just wraps htem
[10:50] <Laurenceb> if you keep each IP packet to an integer number of subpackets it'll be a bit more noise tolerant
[10:51] <SpeedEvil> yeah
[10:51] <SpeedEvil> as will doing local retransmits
[10:51] <Laurenceb> yeah
[10:51] <Laurenceb> really need the lower level to handle auto retransmit
[10:51] <SpeedEvil> does it by default do retransmits?
[10:51] <SpeedEvil> do you get a 'ok' from a recieved packet?
[10:51] <Laurenceb> dont think so
[10:52] <Laurenceb> no, havbe to do that with the controller
[10:52] <SpeedEvil> pity
[10:52] <Laurenceb> you can set it up so it informs you of a corrrectly received packet
[10:52] <Laurenceb> so the uC hase to send a pingback for that
[10:53] <SpeedEvil> if you can just leave the packet in the buffer, and resend if you get a nak, that'd work
[10:53] <Laurenceb> does IP handle retransmit?
[10:53] <Laurenceb> if I fragment the IP packets and send them through the network...
[10:53] <SpeedEvil> yes
[10:53] <SpeedEvil> but fragmenting down to 64 byte packets won't reliably wokr
[10:54] <Laurenceb> that would improve things, but lead to large overhead
[10:54] <Laurenceb> yeah
[10:54] <SpeedEvil> I was meaning keep the serial stream error-checked
[10:54] <Laurenceb> to get ~600Km range you need to withstand ~20% error rate on 255byte packets
[10:54] <SpeedEvil> are the tx and rx buffers the same?
[10:54] <Laurenceb> yes
[10:55] <Laurenceb> - there are two seperate buffers
[10:55] <Laurenceb> but they are identical in design
[10:55] <SpeedEvil> Can you get a 'nak' packet without disturbing hte outgoing buffer?
[10:56] <Laurenceb> dont think so
[10:56] <SpeedEvil> if so, the problem reduces to send 64 bytes from the serial interface - unless there is not 64 bytes within a timeout, then send that. Then monitor for a nak - if you get a nak, tell the hardware to resend the packet. If you get an OK, move on.
[10:57] <Laurenceb> yeah
[10:58] <Laurenceb> it doesnt handle networking tho
[10:58] <SpeedEvil> doesn't handle networking?
[10:58] <Laurenceb> but you could have a cluster of machines sharing a balloon
[10:58] <Laurenceb> inter balloon netwoprks
[10:58] <SpeedEvil> no - you have a serial link
[10:58] <SpeedEvil> then you run ppp over it
[10:58] <SpeedEvil> oh
[10:58] <SpeedEvil> I see what you mean
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[10:58] <Laurenceb> its a lot harder anway
[10:59] <Laurenceb> you cant have yagis on the balloons
[10:59] <SpeedEvil> forgot the end goal
[10:59] <Laurenceb> cluster of laptops sharing an internet connection through a balloon is more practical
[10:59] <SpeedEvil> works for drop sondes though
[10:59] <Laurenceb> useful is disaster areas ect
[11:00] <Laurenceb> you could use the address support in the CC1100
[11:00] <Laurenceb> there is an address byte, so up to 256 devices
[11:00] <Laurenceb> e.g. 255 machines, one balloon
[11:02] <SpeedEvil> or even 256 devices in range
[11:02] <SpeedEvil> and mesh
[11:03] <Laurenceb> yeah
[11:03] <Laurenceb> 254 laptops, one balloon, one calling address
[11:04] <Laurenceb> all net devices call on the calling address and receive an address to use in reply
[11:04] <Laurenceb> *new
[11:05] <Laurenceb> the address list is held by the uC onboard the balloon
[11:05] <Laurenceb> if a device is bead its address is marked as free
[11:06] <Laurenceb> *dead
[11:06] <Laurenceb> anything that hasnt had a packet exchange for a few minuts is wiped
[11:06] <Laurenceb> and it does the same
[11:06] <Laurenceb> something like that anyway...
[11:11] <SpeedEvil> a nasty problem with multiple devices is collision avoidance
[11:11] <Laurenceb> you need to do a random wait if a packet isnt acked
[11:12] <Laurenceb> hmm IRc via balloon :P
[11:14] <Laurenceb> I guess use pppd to connect to a uC that then runs the lower level protocol
[11:14] <Laurenceb> and some slightly different firmware on the balloon
[11:15] <Laurenceb> maybe a secondary downlink on 434 from the balloon with GPS position, status, number of packets received ect
[11:15] <SpeedEvil> GPS + HF + many balloons = beamforming
[11:16] <Laurenceb> lassen iq, AVR, etiny for the balloon and a uC and etiny for each latop and its ready :D
[11:16] <Laurenceb> maybe use hallam and fetrgus's two balloon "hover" technique to stay at altitude for longer
[11:16] <Laurenceb> be interesting to see how well it works on friday
[11:17] <SpeedEvil> well -yeah
[11:17] <SpeedEvil> decided when to cut down yet?
[11:18] <SpeedEvil> or wilkl you be working that out till launch
[11:19] <Laurenceb> probably 6Km
[11:19] <Laurenceb> been playing with the CU spaceflight predictor
[11:19] <Laurenceb> that require 3.5:1 glide to get to ears
[11:19] <Laurenceb> as does 4Km, but theres a risk of houses and the M11
[11:20] <Laurenceb> 6km probably lands in field if it screws up
[11:28] <Laurenceb> hmm from 30Km you could reach all the UK, framnce, belgium, northern coast of spain, germany, parts of poland and denmark
[11:30] <Laurenceb> hmm I'd have to have the cluster on machines as a subnet and use one machine as a router right?
[11:31] <SpeedEvil> pretty much
[11:31] <SpeedEvil> unless you want to play with mesh protocols
[11:32] <SpeedEvil> it's - if you're doing the collision avoidance thing - be essentially like a 10base2 net
[11:33] <Laurenceb> yeah
[11:39] <Laurenceb> hmm actually its not quite that good
[11:40] <Laurenceb> from 33Km, UK, most of rep of ireland, northern france, denmark, germany, belgium, netherlands
[11:40] <SpeedEvil> you mean glide?
[11:41] <Laurenceb> converage with the CC1100
[11:41] <SpeedEvil> at what bps?
[11:42] <Laurenceb> 1.2k
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[11:43] <Laurenceb> hi edmoore
[11:43] <Laurenceb> launch still on?
[11:43] <Laurenceb> for fri
[11:44] <edmoore> aiming to be built for friday, but the actual call is totally weather dependant
[11:44] <edmoore> the weather would need to change a bit from what it is now
[11:44] <Laurenceb> ok
[11:44] <Laurenceb> its not too good for me
[11:45] <Laurenceb> but looks fine for the startracker?
[11:45] <Laurenceb> landing in kent
[11:46] <Laurenceb> whats the problem with the weather?
[11:52] <Laurenceb> SpeedEvil: if many of the users on my netwrok have internet connections, is there a way to use that to improve the reliability?
[11:52] <SpeedEvil> yes - but that gets into the 'mesh protocol' thing
[11:52] <Laurenceb> say only one is the internet gateway, he has to remain connected to the balloon all the time
[11:52] <SpeedEvil> you need to assign weights to routes
[11:53] <SpeedEvil> weights based on connection strength, interferingness, delay, ...
[11:53] <Laurenceb> hmm
[11:53] <Laurenceb> so if I dont do that, one sub address needs to be the IP gateway?
[11:53] <SpeedEvil> pretty much
[11:53] <Laurenceb> sucks
[11:54] <Laurenceb> what happens if I multicast IP packets to several gateways?
[11:55] <Laurenceb> so Id have two identical IP packets going onto the internet
[11:55] <SpeedEvil> yes
[11:55] <Laurenceb> the internet explodes?
[11:55] <SpeedEvil> that works - though you have the problem that you have to have an ISP that'll lety you do that
[11:56] <SpeedEvil> send packets from 2.3.4.5
[11:59] <Laurenceb> well you can setup whatever subnet address you want
[11:59] <Laurenceb> oh... you put that as the from address at the gateway?
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[12:00] <SpeedEvil> you need to setup each gateway machine in that case to tunnel the packets to one machine on the real internet
[12:07] <Laurenceb> yeah
[12:08] <Laurenceb> hmm the balloon can do basic routing if its a star topology
[12:08] <Laurenceb> it can log addresses on the subnet as being gateways
[12:09] <Laurenceb> annoyingly the CC1100 will only allow a device to have one address
[12:09] <Laurenceb> so if you want to uuse the hardware addressing, you have to direct all an internet bound packet to one gateway at a time
[12:10] <Laurenceb> you cant muiltcase iut to all gateways
[12:10] <SpeedEvil> can it do promisc recieve?
[12:10] <Laurenceb> what do you mean?
[12:10] <SpeedEvil> recieve all transmission, including unaddressed
[12:10] <Laurenceb> yeah
[12:11] <Laurenceb> but I was thinking using the 8 bit address feature would speed things up
[12:11] <Laurenceb> guess if you turn it off your free to do mulicasting
[12:12] <Laurenceb> hmm going could do something more organised if your happy for it to remain a star topology
[12:12] <Laurenceb> e.g. the balloon pings each ground station in turn
[12:12] <Laurenceb> then they reply with a packet
[12:12] <SpeedEvil> or every 10th second for 0.5 second, everyone who's not a gateway sets their address to 0, all gateways broadcast to 0, over that 0.5s, with a timeslot based on how good a gateway they are
[12:13] <Laurenceb> hmm
[12:14] <Laurenceb> I like the organised system more
[12:14] <Laurenceb> your basically stuck sith a star netwrok unless theres a yagi on the balloon
[12:15] <SpeedEvil> the above can work somewhat better - if everyone who recieves several good gateways then switches to broadcast mode, and annouces that they're bad gateways over the last 0.25 of that 0.5s
[12:15] <Laurenceb> so may as well have the balloon ping each groundstation with a downlink packet
[12:15] <SpeedEvil> if a balloon only recieves a 'i'm a bad gateway' packet, it can send to that balloon, that can then relay
[12:16] <Laurenceb> well me point is balloon to balloob networking isnt possible with the hardware
[12:16] <Laurenceb> so you may as well use a netwroking system that doesnt support it
[12:17] <SpeedEvil> you can't send to multiple addresses?
[12:17] <Laurenceb> not in the CC1100 hardware address support
[12:17] <SpeedEvil> I mean - send different packets to different addresses
[12:17] <Laurenceb> you could
[12:18] <SpeedEvil> the above only relies on point-point links - and point-multipoint faked by multiple transmitters having the same address
[12:18] <SpeedEvil> multiple recievers
[12:18] <Laurenceb> what I'm thinking now is: the balloon has a star of ground stations, it pins each one in turn with an empty packet or a data downlink packet, then gets an uplink packet in return
[12:19] <SpeedEvil> there are many ways to do this, none really wrong
[12:19] <Laurenceb> with most things youd want everything to go out via the internet
[12:19] <Laurenceb> e.g. IRC
[12:20] <Laurenceb> so all packets coming into the balloon are routed to a ground station with a gateway
[12:20] <Laurenceb> bbl, lunch
[12:44] <Laurenceb> back
[12:44] <Laurenceb> SpeedEvil: pppd expects a transparent serial link right?
[12:44] <Laurenceb> what happens if you start rerouting stuff?
[12:45] <Laurenceb> e.g. if you reroute individual IP packets to different gateways
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[13:12] <Laurenceb> hmm maybe all gateways could have the same address then organise themselves using an internet based server
[13:13] <Laurenceb> they shove all their data off to the server, which then acts as a "virtual gateway"
[13:23] <Laurenceb> SpeedEvil: ping
[14:23] <Ferris-Wheel> ping? pong!
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[15:48] <Laurenceb> hi edmoore
[15:51] <edmoore> hi
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[16:12] <Laurenceb> edmoore: what do you think to going for a landing near the M11 ?
[16:13] <Laurenceb> i.e. about 5 miles west
[16:13] <Laurenceb> rather than ears
[16:17] <Laurenceb> its not as far to glide, I'm not 100% sure of reaching ears
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[16:44] <Laurenceb_> edmoore: does it still look like friday?
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[17:38] <Laurenceb_> rjharrison_: any good with networking?
[17:55] <natrium42> hai
[17:59] <Laurenceb_> are you natrium42?
[18:00] edmoore (n=edmoore@pomegranate.chu.cam.ac.uk) left irc:
[18:00] <Laurenceb_> so.. what do I get if I read from TUN?
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[18:02] <Laurenceb_> IP packets, TCP packets or UDP packets?
[18:07] <Laurenceb_> I'm off nvm
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[18:49] <natrium42> <Laurenceb_> are you natrium42? <-- no, i am his alter ego
[18:50] Laurenceb (n=laurence@dyres221-35.surrey.ac.uk) joined #highaltitude.
[18:50] <Laurenceb> yo
[18:50] <natrium42> <Laurenceb_> are you natrium42? <-- no, i am his alter ego
[18:50] <Laurenceb> lol
[18:51] <Laurenceb> what do you know about /dev/net/TUN
[18:51] <natrium42> tunisia?
[18:51] <Laurenceb> on linux
[18:52] <Laurenceb> it gives you acess to tcp/ip
[18:54] <natrium42> what's giving you problems?
[18:54] <Laurenceb> nothing, I was thinking of using it
[18:56] <Laurenceb> together with the CC1100 tranceivers
[18:59] jcoxon (n=jcoxon@host86-145-224-2.range86-145.btcentralplus.com) joined #highaltitude.
[18:59] <jcoxon> evening all
[19:03] <SpeedEvil> Laurenceb: pppd is a virtial bridge. Packets go in one end of the serial wire, they come out the other end.
[19:04] <SpeedEvil> Laurenceb: disturbing the serial link will not do predictable things to the PPP protocol
[19:04] <Laurenceb> yeah
[19:04] <SpeedEvil> well - it will - it'll bork it.
[19:04] <Laurenceb> so I want to use TUN to grab packets
[19:04] <Laurenceb> then I can break them into subpackets to go over the network
[19:05] <Laurenceb> and reassemble them at a remote "virtual gateway"
[19:05] <Laurenceb> to go onto the internet proper
[19:05] <jcoxon> Laurenceb, that sounds scary
[19:06] <jcoxon> you should use the deep space network form of tcp
[19:06] <jcoxon> they tested that recently
[19:06] <Laurenceb> hehe
[19:06] <SpeedEvil> don't see how that'd work without a lot of hinting
[19:06] <Laurenceb> SpeedEvil: packets get collected by gateways on the radio network
[19:07] <SpeedEvil> 'I'll be able to listen at <orbital elements> <orbital elements> <spacecraft model>
[19:07] <Laurenceb> then sent over the internet to the virtual gateway
[19:07] <Laurenceb> using ssh
[19:07] <Laurenceb> where they are reassembled and go onto the internet through NAT
[19:08] <jcoxon> Laurenceb, the all important question...
[19:08] <Laurenceb> the only bit I dont understand is how to read packets from /dev/net/TUN
[19:08] <jcoxon> but why?
[19:08] <Laurenceb> cuz its cool
[19:08] <jcoxon> hmmmm
[19:08] <Laurenceb> we could have a cluster on machines over france, UK, germany, denmark all sharing a net connection through a balloon
[19:08] <SpeedEvil> http://www.kernel.org/pub/linux/kernel/people/marcelo/linux-2.4/Documentation/networking/tuntap.txt
[19:08] <SpeedEvil> at 1.2kbps
[19:08] <SpeedEvil> The speed!
[19:09] <Laurenceb> god enough for IRC
[19:14] <Laurenceb> does an IP frame contain multiple TCP packets?
[19:15] <Laurenceb> guess it doesnt really matter actually
[19:15] <SpeedEvil> no, on
[19:15] <SpeedEvil> r
[19:15] <Laurenceb> one?
[19:16] <SpeedEvil> oen
[19:16] <Laurenceb> lol ok
[19:16] <Laurenceb> this makes sense
[19:16] <Laurenceb> ok, only other question is how to do NAT at the virtual gateway
[19:16] <Laurenceb> I could write it from scratch
[19:16] <Laurenceb> but thats a pain
[19:16] <SpeedEvil> socks
[19:17] <Laurenceb> well I'll have data coming in over ssh
[19:17] <SpeedEvil> socks -D
[19:17] <SpeedEvil> ssh -D rather
[19:17] <Laurenceb> and being reassembled into IP packets
[19:17] <Laurenceb> at the virtual server
[19:17] <Laurenceb> or gateway
[19:17] <Laurenceb> whatever you call it
[19:17] <SpeedEvil> htere is a socksifier preloadable library
[19:17] <SpeedEvil> that makes every network connection go over a socks proxy
[19:17] <Laurenceb> right... I'll look into it
[19:17] <SpeedEvil> tor.org linked from should be
[19:19] <Laurenceb> you mean .orig ?
[19:22] <Laurenceb> so a sockified program goes through socks ?
[19:22] <SpeedEvil> tor is the onion router
[19:23] <SpeedEvil> it's a randomised router that switches through 5 o more encrypted proxies
[19:23] <SpeedEvil> and uses socks to connect to it on the user end
[19:23] <Laurenceb> hmm
[19:23] <Laurenceb> can I keep all this confined to the virtual sever machine?
[19:24] <SpeedEvil> [][SpeedEvil] [] [Query: shellevil]
[19:24] <SpeedEvil> mejh
[19:24] <SpeedEvil> http://www.torproject.org/
[19:24] <Laurenceb> so the IP packet reconstruction happens there, and the reconstructor talks to socks?
[19:24] <SpeedEvil> yeah
[19:25] <Laurenceb> so each peer has a short (8 bit) local address
[19:25] <Laurenceb> the reconstructor knows that address
[19:25] <SpeedEvil> socks lets you tunnel all outgoing connections through a ssh tunnel
[19:26] <Laurenceb> yeah, but thats not what I have
[19:26] <Laurenceb> I us the ssh tunnel to send CC1100 subpackets
[19:26] <Laurenceb> to the virtual gateway
[19:26] <SpeedEvil> ah
[19:26] <Laurenceb> then once there they are reconstructed
[19:26] <Laurenceb> and NAT ed
[19:27] <Laurenceb> the entire radio netwrok runs on CC1100 subpackets
[19:27] <Laurenceb> the peers construct them using /dev/net/TUN
[19:27] <Laurenceb> the gateways ssh them to the virtual gateway
[19:27] <Laurenceb> which then reassembles IP packets
[19:28] <Laurenceb> and does NAT to allow the peers to form a subnet
[19:29] <SpeedEvil> or you speak socks direct
[19:29] <SpeedEvil> http://en.wikipedia.org/wiki/SOCKS
[19:29] <Laurenceb> I could write my own NAT... its not that hard
[19:29] <SpeedEvil> no point reinventing
[19:30] <Laurenceb> just map packets from a remote IP back to their origionator
[19:30] <Laurenceb> if there are more than one origionator, do port mapping
[19:30] <SpeedEvil> stuff each packet into an ethernet frame, with an appropriately set MAC based on the packet number, and it all just works
[19:30] <Laurenceb> oh well... I'll have to read up as its a bit over my head
[19:30] <Laurenceb> hehe
[19:31] <Laurenceb> that would actually work
[19:31] <Laurenceb> lol
[19:31] <SpeedEvil> that's the nice thing about networking
[19:31] <SpeedEvil> look backl enough, and someones done everything with it
[19:31] <Laurenceb> hmm actually that would be a bad solution
[19:31] <SpeedEvil> though you can still get patents on it
[19:32] <Laurenceb> well I've got to go on a mission to find a 1m850cm cardboard box before homebase coloses
[19:32] <Laurenceb> bbl
[19:32] <SpeedEvil> wave
[19:32] Action: SpeedEvil hopes Laurenceb means 850mm
[19:32] <SpeedEvil> or it'll be tricky to manage on a bike
[19:44] <jcoxon> ping rjharrison_
[19:47] <shellevil> Laurenceb: to be annoying.
[19:47] <shellevil> Laurenceb: I'll mention that one ATM cell fits nicely in the 64 byte packet
[20:20] kc0wys (n=kc0wys@75-130-209-194.dhcp.stls.mo.charter.com) joined #highaltitude.
[20:26] <G8KHW> atm cells are 53 bytes long with a 48 byte payload
[20:28] <jcoxon> G8KHW, any sight of those radio modules?
[20:28] <Laurenceb> back
[20:28] <Laurenceb> have cardboard :P
[20:29] <Laurenceb> from skip at back of B&Q :D
[20:30] <G8KHW> jcoxon: no not yet
[20:30] <G8KHW> :-(
[20:34] <jcoxon> am working on the DL Python Client
[20:36] <Laurenceb> shellevil: for your ethernet idea, I'd create fake ethernet packets that looked like they case from another machine ?
[20:37] <Laurenceb> i.e. make up a mac address
[20:37] <shellevil> lau: yes
[20:37] <Laurenceb> oh cool
[20:37] <Laurenceb> didnt know you could do that
[20:37] <shellevil> Laurenceb: so you have 255 seperate mac addresses
[20:37] <shellevil> and NAT and stuf 'just works'
[20:37] <Laurenceb> so the router/adsl modem will think the machines are physically connected
[20:37] <shellevil> yes
[20:37] <Laurenceb> thats awesome
[20:37] <Laurenceb> :P
[20:38] <shellevil> Sat modems - 2000 quid - 5 quid/meg - 512kbps
[20:38] <Laurenceb> hehe
[20:38] <shellevil> I guess if you've got the money
[20:39] <Laurenceb> my other idea was to sinc the gateways during uplink to the balloon
[20:39] <Laurenceb> its probably too hard
[20:39] <shellevil> and want internet on your boat out in the pacific, there isn't much option
[20:39] <shellevil> alternatively
[20:39] <Laurenceb> but if they all sent the same packet at the same time - accounting for speed of light
[20:39] <shellevil> every reciever is set to the same address
[20:39] <shellevil> and you simply pretend to be ethernet with collision sense and detect
[20:39] <Laurenceb> noo
[20:40] <shellevil> but with smaller frames
[20:40] <Laurenceb> I'd have the balloon act as a hub
[20:40] <Laurenceb> and ping each connected peer in series
[20:40] <shellevil> ideally you want to control power down to minumum too
[20:40] <Laurenceb> yeah guess
[20:40] <Laurenceb> I like the ping in series idea
[20:41] <Laurenceb> then all the gateways have the same address
[20:42] <Laurenceb> so any one of them can pick up a downlinked packet from the balloon
[20:42] <Laurenceb> the problem is you have find the one with the best signal strenght and use that for the uplink to the balloon
[20:42] <Laurenceb> unless you can sinc all the gateways
[20:43] <Laurenceb> and transmit the same packet from all of them at once
[20:43] <shellevil> light speed kills that
[20:44] <Laurenceb> yeah
[20:48] Action: shellevil stabs the speed of light.
[20:48] Action: shellevil wants his runcible.
[20:56] <Laurenceb> http://www.usenet-forums.com/linux-networking/59717-need-help-raw-ethernet-socket-question.html#post210290
[20:56] <Laurenceb> doesnt look too hard
[20:59] <Laurenceb> I guess each CC1100 packet would have a three byte header inside the payload with peer address, and a two byte subpacket counter
[21:11] <Laurenceb> then the balloon loops round to each connected peer, pinging it with data and waiting for a response/timing out. every so often it pings some "register new peer" address
[21:11] <Laurenceb> and any new peer wanting to connect replies and is assigned an address on the subnet
[21:12] <Laurenceb> so there 253 poss peers, then one adress for the balloon, one for registering, and one for gateways
[21:14] <G8KHW> I think your re-inveting TDMA
[21:14] <Laurenceb> sure
[21:14] <Laurenceb> :P
[21:16] <Laurenceb> I guess its not that useful with sat modems, but it would be so cool to setup something similar to the "hover at apogee" technique on NOVA10 at around 30Km and run a network over 600Km radius
[21:23] <Laurenceb> on friday you could float for over 2 hours at 33Km
[21:24] <gordonjcp> wonder what the crack with balloon-flown repeaters would be?
[21:25] <natrium42> Laurenceb, when are you launching on friday?
[21:26] <Laurenceb> not sure
[21:26] <Laurenceb> prob midday
[21:27] <Laurenceb> hmm looking at the CU spaceflight predictor you could float for 3.5 hours at 33Km if you launched at 9am
[21:27] <Laurenceb> landing at 3pm
[21:27] <Laurenceb> near Dover
[21:28] <natrium42> neat
[21:29] <Laurenceb> gordonjcp: you could get up to 1300Km between repeaters, but you'd never get that range without a steered yagi or very high power
[21:30] <Laurenceb> balloon to balloon is hard
[21:38] <Laurenceb> yeah rogallo fits perfectly in my box :D
[21:42] <SpeedEvil> A) free calls as BT has not apparantly setup billing on my line properly.
[21:42] <SpeedEvil> B) being unable to open a bank account as they have not sent me a bill.
[21:42] Action: SpeedEvil sighs.
[21:44] Action: Laurenceb forwards SpeedEvil to customer support aka G8KHW
[22:32] <jcoxon> ping rjharrison_
[22:44] Action: Laurenceb has 4GB ram
[22:44] <Laurenceb> nce and fast :P
[22:44] <Laurenceb> upgraded from 1GB
[22:46] <jcoxon> Laurenceb, you and ram!
[22:47] <Laurenceb> ram is all you need
[22:47] <Laurenceb> never have to close a tap again
[22:47] <Laurenceb> *tab
[22:48] <Laurenceb> my laptop is interesting, they have somehow coated the inside of the plastic case with copper
[22:48] <Laurenceb> for shielding
[22:50] <Laurenceb> also has ufl connectors on the wifi :P
[22:51] <Laurenceb> has anyone ever built some sort of wifi switch? I'm wondering if you could stick an sma socket in the side of the machine
[22:53] <shellevil> Laurenceb: you put it in a vacuum chamber and evaporate copper, while whacking it with microwaves in a special way
[22:53] <Laurenceb> whack the plastic?
[22:53] <Laurenceb> so its heated at the surface?
[22:54] <shellevil> the plastic is unaffected by the microwaves
[22:54] <Laurenceb> oh so you have copper plasma?
[22:54] <shellevil> the microwaves sort-of-spread round the vaporised/ionised copper
[22:54] <shellevil> yeah
[22:54] <Laurenceb> neat
[22:54] <Laurenceb> I tried that with graphite and high voltage capacitors
[22:54] Action: shellevil has a vacuum pump in the attic he means to do that with
[22:54] <Laurenceb> - the vacuum
[22:55] <shellevil> I want - for no reason at all - to make metallic pictures as mirrors
[22:55] <Laurenceb> managed to coat plastic in graphite fairly well
[22:55] <shellevil> copper, brass, gold, platinum, purple plague
[22:55] <Laurenceb> 0.5mm pencil lead ~ 4cm over the surface
[22:55] <shellevil> (gold + aluminium - you get purple)
[22:55] <Laurenceb> nice
[22:56] <shellevil> I forget the dullest - lowest visible reflectivity - I think it was palladium
[22:57] <shellevil> have I mentioned the sheet metal brazed to tiny wires as spacers here?
[22:57] <shellevil> http://www.bbc.co.uk/radio1/
[22:57] <shellevil> check the tag cloud on the bottom :)
[22:58] <Laurenceb> haha
[22:58] <Laurenceb> hmm with http://www.radioworld.co.uk/~radio/catalog/a430s15r-diamond-430440mhz-70cm-yagi-p-3963.html?osCsid=bf06b83cf4408bae6f9b92b9b4d7dfc0
[22:58] <shellevil> http://www.fibretech.com/products_fibrecore.htm
[22:59] <shellevil> that stuff is cool
[22:59] <shellevil> though probably not very cheap
[22:59] <Laurenceb> and a 1/4 wave ant on your balloon you can get 600Km range
[22:59] <Laurenceb> at ~50% packet loss
[22:59] <shellevil> unsure about multipath
[22:59] <shellevil> I mean - sure you get the range in theory
[22:59] <gordonjcp> http://science.slashdot.org/article.pl?sid=09/03/18/1645216
[23:00] <Laurenceb> yeah its gerard
[23:00] <shellevil> neat
[23:01] <Laurenceb> hmm is there a way to find the current data with php?
[23:01] <shellevil> current data?
[23:01] <Laurenceb> my rogallo tracker needs to find the logfile, and they are stored using the date as the name
[23:02] <Laurenceb> *date
[23:02] <shellevil> ah
[23:02] <shellevil> systime()
[23:02] Action: shellevil has no clue
[23:02] <Laurenceb> I'll ask on php
[23:03] <shellevil> oh - and it's looking like borrowing a reciever for the flight is a no for me.
[23:03] <shellevil> too much going on
[23:08] <jcoxon> shellevil, fair enough
[23:12] Action: shellevil wishes life'd cooperate at some points.
[23:12] <shellevil> you've got anyone else interested in picking it up?
[23:13] <jcoxon> yeah a couple
[23:13] <jcoxon> need a few more people on the North America side and also some europeans
[23:17] <shellevil> hmm - there are islands in mid-atlantic
[23:17] <shellevil> not many, and quite southerly
[23:18] <jcoxon> Newfoundland will be very helpful
[23:19] <jcoxon> and a canary island listenier
[23:19] <shellevil> http://en.wikipedia.org/wiki/Flores_Island_(Azores)
[23:20] <shellevil> I suppose actually - chances of hams on those islands are probably much higher than the population might lead you to expect
[23:20] <jcoxon> oh yeah
[23:21] <jcoxon> once i've got hte client sorted i'll start looking into contacting a few people
[23:21] <jcoxon> might be able to tap into the old UTARC list for snox flights
[23:22] <shellevil> there are 'digital radio' lists that may work too
[23:23] <shellevil> http://groups.google.co.uk/groups?source=ig&hl=en&rlz=&=&q=psk31&lr=&um=1&ie=UTF-8&sa=N&tab=wg
[23:24] <shellevil> and how I hate the eeepcs 'middle button'
[23:24] <Laurenceb> bermuda
[23:25] <Laurenceb> ah this is lovely...huge gnuplot graphs, openoffice, hundereds of tabs, google earth
[23:25] <Laurenceb> 4GB ftw
[23:27] <shellevil> http://groups.google.co.uk/group/rec.radio.amateur.digital.misc/topics?hl=en&ie=UTF-8
[23:27] <shellevil> seems to have some messages still.
[23:27] Action: shellevil bemoans the death of usenet
[23:28] <jcoxon> shall have a think
[23:28] <jcoxon> night all
[23:28] jcoxon (n=jcoxon@host86-145-224-2.range86-145.btcentralplus.com) left irc: "Leaving"
[23:28] Action: Laurenceb ponders shoving a power amp onto the CC1100
[23:28] <Laurenceb> cya
[23:28] <Laurenceb> ooh too late
[23:28] <Laurenceb> hmm apparently its been used for picosats
[23:30] <Laurenceb> actually not that ic, older stuff from the "chipcon" line
[00:00] --- Thu Mar 19 2009