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[07:31] juxta (juxta@ppp203-122-193-94.static.internode.on.net) left irc: Ping timeout: 265 seconds [07:34] natrium42 (~natrium@CPE000625d867e2-CM0014045885be.cpe.net.cable.rogers.com) left irc: Quit: Leaving [07:43] DagoRed (~dago@j15-1.nat.iastate.edu) left irc: Quit: Off to bed, wish I could chat longer. [08:12] Stratisphere (~Stratisph@193.200.145.254) joined #highaltitude. [08:12] hey all [08:12] quick question if thats ok [08:12] i'm just about to order a ntx2 [08:13] which freq is best advised given what you fantastic lot listen on? [08:13] At 434.65MHz: NTX2-434.65-10 - Transmitter [08:13] NRX2-434.65-10 - Receiver [08:13] [08:13] At 434.075MHz: NTX2-434.075-10 - Transmitter [08:13] NRX2-434.075-10 - Receiver [08:29] TraumaPony (~TraumaPon@203-206-28-19.dyn.iinet.net.au) joined #highaltitude. [08:37] hey are you in the UK ? [08:37] Stratisphere [08:37] if so people tend to use 434.075 [08:38] recieve you will need something a little more sensitive than the NRX module [08:38] like say Yaesu FT-817 seems to be a popular choice [08:53] hey Upu [08:53] yeh I read it on the alien site so I got that one [08:53] Hi there Stratisphere [08:53] and yeh, i assumed the receiver wouldnt be good enough [08:54] any idea on a semi-decent supplier for the yaesu?: [08:54] I got mine from http://www.radioworld.co.uk/catalog/yaesu-ft817nd-transceiver-p-348.html [08:54] oh wow! Ł500 lol [08:55] yeah they aren't cheap sadly [08:55] get the NTX module direct from Radiometrix will probably be cheaper [08:55] are you in the UK ? [08:55] yeh chucked them an email a few min ago [08:55] yup, i'm the network manager of a secondary school [08:55] Ah ok where abouts ? [08:55] planning the project as a surprise science project for the kids [08:55] herefordshire [08:56] kk sure there is someone about who will lend a hand with a radio [08:56] jcoxon probably has a radio you can borrow [08:56] cool, my granddad has a scanner, pretty certain it goes to 434.075... just need to check it does ssb [08:57] you guys really do live up to your kindness on the web lol [08:57] yeah alot don't they just do FM [08:58] also if you want to just fly a payload you may be able to "hitch" a lift on another balloon that already has tracking on it [08:59] something I might do after I'm happy my launches are sucessful [08:59] yeh could be an idea [08:59] mind you, the cost for the balloon & gas doesnt appear to be that much compared to the one-time cost of the electronics [09:00] and we plan to do this many more times :D [09:01] well might as well launch a few at a time then :) [09:01] I think CUSF launched 4 payloads at once ? I might be wrong [09:05] rharrison (~rharrison@gateway.hgf.com) joined #highaltitude. [09:09] morning Rob [09:10] ha cool. whats the general idea on max weight? obs it depends on the balloon you use, but whats the max lifted [09:10] ? [09:10] think CUSF lifted 3kgs up on a 1.6kg balloon but you're not going to break alititude records with that weight :) [09:11] I might be totally wrong on this [09:11] I think payloads are normally in the 0.5-1kg region [09:12] 3kg!... Hmm... I think some of our students weigh less than that :P [09:21] lol [09:24] UpuMobile (~UpuMobile@smtp.nevis.co.uk) joined #highaltitude. [09:25] UpuMobile (~UpuMobile@smtp.nevis.co.uk) left irc: Client Quit [09:26] UpuMobile (~UpuMobile@smtp.nevis.co.uk) joined #highaltitude. [09:30] SpeedEvil1 (~user@tor/regular/SpeedEvil) left irc: Quit: Leaving. [09:30] SpeedEvil (1000@tor/regular/SpeedEvil) joined #highaltitude. [09:42] hi [09:52] Stratisphere, Upu: its possible to receive 434MHz using a cc1020 from Ti - they have an eval board [09:54] tho i havent done this for actual flights [09:55] is it sensitive enough you think for HAB flights? [09:56] noise figure is about 7dB [09:56] it would benefit from a LNA on the front [09:57] Hmm [09:57] possibly 6 - it depends how the decoding works [09:57] UpuMobile (~UpuMobile@smtp.nevis.co.uk) left irc: Ping timeout: 240 seconds [09:57] you can get LNAs with 1 or 2 dB - so thats at least 4dB gain [09:59] cool... lol there's alot of learning I need to do! [09:59] http://gb.mouser.com/ProductDetail/Texas-Instruments/CC1020EMK-433/?qs=sGAEpiMZZMuyoPqaVfyaE2PDrM%2fQ%252bmBaP06rCKRTCqk%3d [09:59] 4dB about 60% more range [09:59] *is [10:00] will read now! :) [10:00] but yeah if you are new to radio hacking a cc1020 eval kit is kind of complex [10:00] i havent actually got the full setup working myself so not sure how good it is [10:00] lol [10:02] UpuMobile (~UpuMobile@smtp.nevis.co.uk) joined #highaltitude. [10:07] test [10:23] hello world [10:23] morning [10:25] possibly. [10:26] m1x10 (m1x10@ppp089210139002.dsl.hol.gr) left irc: Quit: I eat electrons for breakfast and I vomit thunders [10:41] UpuMobile (~UpuMobile@smtp.nevis.co.uk) left irc: [10:44] m1x10 (m1x10@ppp089210139002.dsl.hol.gr) joined #highaltitude. [11:49] chris_99 (~chris_99@84.93.186.126) joined #highaltitude. [11:49] chris_99 (~chris_99@84.93.186.126) left irc: Changing host [11:49] chris_99 (~chris_99@unaffiliated/chris-99/x-3062929) joined #highaltitude. [12:06] chris_99 (~chris_99@unaffiliated/chris-99/x-3062929) left irc: Ping timeout: 252 seconds [12:46] eroomde (~ed@nessie.habhub.org) joined #highaltitude. [13:02] jcoxon (~jcoxon@cpc1-lanc4-0-0-cust720.3-3.cable.virginmedia.com) joined #highaltitude. [13:04] 1/2 day! woohoo [13:12] guess i'm the only one :-p [13:12] hey [13:12] what do u mean 1/2? [13:12] half day [13:13] yeah for what? [13:13] oh from work [13:13] haha [13:13] :) [13:13] as i work slightly longer days i'm meant to have an afternoon off a week to make sure my hours are legal [13:13] however i'm usually too busy [13:13] jcoxon, it's ok for some [13:14] taken me 2 months to get an afternoon off [13:14] :-p [13:14] just been on an ordering spree [13:14] ordered new pcbs, components, radio modules... [13:15] I nearly did a propane powered launch yesterday. [13:15] LazyLeopard (~irc-clien@chocky.demon.co.uk) joined #highaltitude. [13:15] http://www.flickr.com/photos/14560445@N08/5016093779/ [13:16] Starting fire with a blowtorch on low, and walked away for a moment to get other stuff to put on. [13:16] Got distracted, and noticed that the blowtorch had gotten really, really loud. [13:16] Fortunately, no explosion. [13:17] eek [13:17] The knob and all the plastic on it melted though [13:18] While clearing up, I found some more suitable plastic for balloons. :) [13:48] ping rj [13:48] ping rharrison [13:48] pong [13:48] to the bat cave (#ha2) [13:59] Simon-MPFH (~simon@phantom.mpfh.co.uk) left irc: Quit: Leaving [14:00] hmm [14:00] hey jcoxon [14:00] you around? [14:00] yup [14:00] here's a kind of n00b question... [14:00] avr-gcc, as in, what comes with avr studio [14:00] is this also a c++ compiler? [14:00] i.e. could i dump in some c++ stuff into my code, and have it still compile? [14:01] coolo, I'm the network manager for a secondary school in herefordshire. We're planning a HAB launch as a surprise science project for some of our kids, we've got alot of stuff already planned out and parts ordered [14:01] one bit we may be lacking is a decent radio to pickup the telemetry (if my granddads doesnt pickup SSB) [14:01] not many scanners do SSB at UHF frequencies [14:02] upu suggested you may be able to lend us one [14:02] Darkside: yes. but I think maybe use avr-g++ [14:02] hmm ok [14:02] indeed i may... [14:02] Randomskk: is that what arduino uses? [14:02] Darkside: maybe. both should be on your system. avr-gcc should work with c++ anyway though, name files cpp or cc [14:02] ok [14:03] cool, well nothing is written yet so no worry/rush. But if it's a case where we cant get one ourselves I would be very grateful if you could [14:03] i've got a spare yaesu ft790r [14:03] thats the one you leant to the alien HAB isnt it? [14:03] (i've been doing alot of reading lol) [14:03] yup [14:03] cool [14:04] awesome, well i'm going to be idling here most days now :) [14:04] okay cool [14:09] we've just ordered alot of kit from sparkfun including stacks of sensors. I've also just placed an order for the NTX2 :) [14:09] sweet [14:10] as soon as i've got a demo kit working and together we'll weigh it up and see what balloon we need then order a few :D:D [14:10] Stratisphere, yeah thats the best approach [14:10] lol everyone loves the NTX2.. [14:11] once i miniaturise my HF board, i'll release all the data for it [14:11] Darkside: we can't transmit HF from balloons in the UK, though [14:11] :/ [14:11] gotta use license free bands [14:11] really [14:12] even with an amateur license? [14:12] namely 434mhz, ish. and 10mW transmit power. [14:12] regretably yes. [14:12] UK amateurs are not allowed to operate airborne [14:12] aww what [14:12] hence 10mW at 434MHz [14:12] juxta managed to run a VHF repeater airborne here :/ [14:12] the same band car keys use to remote unlock, and the same kind of power >__> [14:12] your amateur licenses are like, better [14:12] haha [14:12] but they cost money here :P [14:13] Randomskk: but their aviation regs are more strict [14:13] Darkside: ours cost a little bit [14:13] russss: true, we do have a fairly good time with that [14:13] also like 10mW is enough for anybody [14:14] chris_99 (~chris9001@unaffiliated/chris-99/x-3062929) joined #highaltitude. [14:18] pffff just read a paper by one of my supervisors at uni about measuring the gain patterns of HF antennas [14:19] tl;dr version - get a helicopter, stick a known antenna underneath it (dipole) and fly it around the unknown antenna [14:19] i lol'd [14:19] it works extremely well too, the experimental data is very cool [14:19] Darkside: that's exactly what they do [14:19] http://docs.google.com/viewer?a=v&q=cache:dUhhXZCDppcJ:dspace.dsto.defence.gov.au/dspace/bitstream/1947/4315/1/DSTO-TR-0654.pdf+dr+chris+coleman+RF&hl=en&gl=au&pid=bl&srcid=ADGEESgaardYaZjVQRuaai0AJMCSfXCCYLVF0sA_iA3WIS1TWG0FLbrHrfLX--WR11OUcDF3oi_D3FuTuRJi75D82Jd3iqnNBM1Yu24Fldy5MnAjPvSxXy_OHr37nv583-VLgZ7SRQdi&sig=AHIEtbQRRmlrsey4CxQsDftCyyt84MvnIw [14:20] basically taking the classic method of measuring small antennas to the extreme [14:20] which is cool [14:20] i have been talking to someone (Randomskk listen in) who makes super-resolution HF arrays for direction finding [14:20] and they fly a helicopter about to build a model of the complex manifold [14:21] hahahaha [14:21] nice [14:21] Randomskk: i got cut off as we were talking about direction finding [14:21] but there's more to say [14:21] http://www.cambridge.org/us/catalogue/catalogue.asp?isbn=0521834813 <-- thats the textbook my supervisor wrote [14:21] I read a paper that went through the basics of beamforming and using it for super resolution DF [14:21] Darkside: invalid isbn [14:21] hmm [14:21] but it didn't really get into the complexities of implementation [14:22] Randomskk: mm [14:22] eroomde: check you're copying it right [14:22] just like "yeea change the phase and such" [14:22] did it cover the MUSIC algorithm? [14:22] that's basically the key [14:22] and the secret to how we should make one [14:22] as then we could have several balloons in the sky at once on 434.650 and decode all of them individual with special filtering [14:22] I don't believe it did [14:23] rather than some kind of frequency or temporal bs, which are either scarce or complicated [14:23] cdma :D [14:23] ok, well the music algorithm is basically this (and it's gorgeous in its simplicity) [14:23] eroomde: whereby the receiver beamforms to just receive from the desired balloon? [14:23] just do CDMA :D [14:23] synch the timing with gps [14:23] cdma through a 3khz LPF-ed VCO? [14:24] oh man i need to try this [14:24] i'd like to see that [14:24] lol [14:24] well, a cdma-like thing [14:24] Randomskk: so have an array of say 8 antennas [14:24] ignore the geometry for now. say an octagon but in reality not as that's full of nulls and stuff. but whatever, and array of 8 antennas [14:25] you can describe the covariance between antenna x_n and antenna x_(n+a) with a complex number [14:25] representing the phase and magnitude relationship between each of them [14:26] so you can then make a covariance matrix (8x8 in our case) of complex values representing the relationship of the incoming signal between each of the antennas [14:26] insert maths, receive signal [14:26] it'll be diagonally symmetric right (relationship between x_1 and x_2 is the same as between x_2 and x_1) [14:26] with you so far [14:27] so once you have that complex covariance matrix, you can do an eigen decomposition on it [14:27] yeah [14:27] this would be for a fixed station, right? [14:27] thats how MIMO works [14:27] and each of the eigen value and vecotr pairs you get is a signal that is comping into the array [14:27] coming* [14:27] eroomde: need cc1020s with time sync [14:27] for the ants [14:27] you then have to convolve these eigenpairs with the complex manifold of the array (because it's not going to be a pefect hemisphere). that's basically just a calibration step [14:28] and you can say 'i have a signal at 21.2 degrees azimeth, 14 degreese elevation, with an SNR of 2db) and you're done [14:29] very cool [14:29] beautiful in its simplicity though I get the feeling finding the complex manifold is nontrivial and constructing antennas with electronics to quickly read a synchronised phase and amplitude is also a bit tricky? [14:29] so you can coule a az-el plot on your display which would have small gausian clouds of samples you were getting, and write special demodulators - so basically you see a cloud of points and say 'decode that cloud there' and it'll be neva25 or whatever [14:29] Randomskk: exactly [14:29] id go with cc1020 [14:29] so the trick is to make an array such that the menifold is as regular as possible [14:29] and then treat it as a hemipshere [14:29] but not sure of the best way to time sync [14:30] Laurenceb: ooh i've heard of those chips.. [14:30] maybe a central board [14:30] Laurenceb: does it have a clock in? if you fed them all with the same clock source would that actually work? [14:30] yes [14:30] clk in and out [14:30] problem is boards at each ant or central board and coax? [14:30] Randomskk: so that conversation I had with this guy (who works at roke manor and makes such a system for the miltary) is on the design of a simulated annealing algorithm to iterate to a good manifold design [14:30] eroomde: does that work in reverse to transmit in a given direction? you can find a symmetric matrix from the eigen decomposition, right? [14:31] also you definitely definitely want unresonant elements in the array [14:31] otherwise the mutual coupling just wrecks any chance you have of a vaguely even manifold [14:31] right [14:31] unresonant at incoming signal frequency or..? [14:31] yes [14:31] I guess that makes transmitting more of a pain? [14:31] you may say 'gah! detuned!?!?!' but the improvements you get in SNR from the special filtering stuff more than sort that [14:31] yeah - need larger ants [14:31] fair enough [14:32] ive got a cc1020 SDR thing hacked up on breadboard [14:32] eroomde: better than the track o tron? [14:32] guess a central board isnt scalable [14:32] you can actively shpae the electronic array manifold (which is something you design based on starting with a fairly even physical one) to put nulls in the direction of interfering sources, for instance [14:33] yea, that's quite neat. isn't that kind of how you do the superresolution DF? point nulls? [14:33] Randomskk: maybe not better than some really long yagis altimately, but if you have several balloons in the air, way better [14:33] could you use it with yasgis? [14:33] yuck [14:33] this sounds like a lot of effort to go to for tracking balloons :P [14:33] yes... [14:34] i mean sure, of course right. but analysing your manifold would be torturous [14:34] yeah actually thats stupid [14:34] the other thing that looked interesting is UWB but that seems like it would not be license free exactly [14:34] it's probably overkill for balloons but as an open hardware project it f*cking rocks [14:34] just steer the yagis manually [14:34] and add adjustable delay lines in software [14:34] and you'd get all these super keep DX clubs making them in a heart-beat as you could absolutely *cream* competitions with such a set-up [14:34] MUSIC for that sort of setup itsd the best idea [14:35] super keen* [14:35] i'm very surprised at the UKs radio regs.. [14:35] lol reading this has been cool [14:35] there's gotta be something you cna use airborne [14:35] Darkside: can you give me the title of that book? I'll look it up myself [14:35] apart from the 433MHz ISM stuff [14:35] Darkside: yes. 10mW 434mhz [14:35] i feel like i've been privvy to some military secret document (aka, I dont understand a single bit of it lol) [14:35] Darkside: there are a couple of others [14:35] there's a little 868 I think, and some 2.4ghz though FSPL is horrific [14:35] 167mhz at 500mW iirc [14:35] http://www.amazon.com/Introduction-Radio-Frequency-Engineering/dp/0521834813 [14:36] its our uni's 3rd year RF engineering textbook [14:36] we use a bit of it in 4th year too, mainly s-matrix stuff [14:37] s-matrix? [14:37] sounds a bit dark [14:37] scattering matricies [14:37] i.e for amplifiers, filters, basically any device [14:37] I have never done any academic courses on anything radio so quite a lot of it is a bit unknown to me [14:37] i'm happier once it's a bitstream [14:37] hahaa [14:37] yes [14:38] signal processing ftw [14:38] Randomskk: but yes a super resolution UHF rig would be amazing [14:38] still, i'm wondeirng if it would be possible to do something like CDMA on that band [14:38] and would hopefully fit on a roof rack [14:38] yes, of course [14:38] and quite likely no one would ntoice [14:39] if you did code hopping [14:39] not quite the same as CDMA, but signals added together, then pulled out at the receiver with dsp [14:39] eroomde: an FPGA doing maths, 8 or so antennas with cc1020s and a central clock, an output stream of vectors and signals? [14:39] easy yes [14:39] does the decomposition give you the momentary signal amplitude? [14:39] with the direction as the vector? or what [14:39] correct [14:39] http://focus.ti.com/lit/ds/symlink/cc1020.pdf clk input on the osc pin [14:39] it's all done in a complex space which gives you phase and mag [14:39] all that info is preserved [14:39] neat. [14:39] apart from when you decimate to baseband [14:40] and yep, FPGA to USB or something [14:40] well hang on [14:40] Randomskk: yeah maybe stick a cc1020 on each ant [14:40] I really really want to get to use my fpga for something [14:40] fpga doing the packing and usb [14:40] big chunky fpga.. [14:40] I am kind of tempted to try and implement HDCP in it [14:40] you would to do the dsp on a cpu i think [14:40] on a laptop [14:40] ah, fair enough [14:40] Randomskk: what fpga? [14:40] need some sort of digital comms to the ants tho.. [14:40] Darkside: spartan 3e, though I can get others [14:40] yeah i have a spartan 3e board [14:40] yeah spartan is nice [14:41] got a friend working on a virtex 6 at uni [14:41] veeeeeeeeeeery expensive fpga, the virtex 6 [14:41] and he's got a gameboy emulator running on it :P [14:41] yea really. the cost on the big ones goes up dramatically [14:41] using 6 microblaze cores [14:41] running at 150MHz.. [14:41] wow [14:41] i think you'd want to use the CPU to do the music stuff. there's plenty of horsepower and it'll make it a million times easier to integrate with special decoders [14:41] hehe [14:42] http://retromaster.wordpress.com/a2601/ did an atari 2600 including cpu, memory and graphics unit on a spartan 3e [14:42] its more a research project about how to do inter-core communication efficiently than anyting [14:42] how far apart would the ants be? [14:42] ~1m or so? [14:42] Laurenceb: that's the hardest bit [14:42] designing the manifold [14:42] eroomde: that's true. easier to program too, at the end of the day [14:42] youd really need a seperate spi bus to each ant [14:42] it think after that you just need coherent receivers and decimation and basically shove it into usb. [14:42] as it has to run at a few mbps [14:42] Laurenceb: easily done on an fpga [14:43] yes [14:43] spi? it's gonna have to be quite high bandwidth i think [14:43] as is usb, there are ip cores for that [14:43] ~2 to 4 [14:43] mbps [14:43] you'd probably want to grab like 1mhz bandwidth [14:43] spi can do quite high bandwidth [14:43] as a bus, anyway [14:43] the cc is going to be the limiting factor [14:43] Or you don't bother. [14:43] eroomde: cripes [14:43] you can do 2 bit conversdion on the cc [14:43] with 8 antennas that's 8mhz bandwidth at whatever adc resoiltuion your budget will stretch to [14:43] eroomde: just make your own down converted and stick a big-ass ADC on there [14:44] And you have a 4 quadrant mixer at each antenna, that feeds onto an IQ summer [14:44] swhy the bandwidth? [14:44] surely a few tens of Khz would be fine [14:44] so you can see most of 70cm [14:44] Do you really care about the steering that much [14:44] just enough to see the signal [14:44] the point of these systems is to be able to grab all of a a band and monitor it [14:44] fairdoos [14:44] i was thinking just for monitoring [14:44] and you do really need lots of bits on your ADC - that's very important in this app [14:44] - rx etc [14:45] eroomde: define 'lots' [14:45] you can go to 3 bit [14:45] 24 would be nice [14:45] jeez [14:45] not kidding [14:45] $$$$$$$$ [14:45] so think about it [14:45] no way thatd be practical [14:45] ths USRP2 is only 16 or something, isn't it? [14:45] with a single antenna, when you have a balloon your are listening to at 10mW 400km away, that's fine [14:45] with multiple ants itd get crazy [14:46] when someone on their 5W handheld 1km talks on your frequency, you are utterly trashed - nothing you can do [14:46] so who cares [14:46] but with special multiplexing, you can still see both the balloon and the handheld [14:46] how so? [14:46] but ONLY if you have the dynamic range to see both of them despite the huge difference in SNR [14:46] switch to a seperate frequency? [14:46] no, this is the point of the special stuff [14:47] you can have lots of things on the same frequency [14:47] Darkside: USRP2 is 14 bits receive, 16 transmit [14:47] but as long as they're in difference places you can split them up [14:47] it's like FDM or TDM [14:47] but SDM in this case [14:47] guess so [14:47] that's the joy of this sytem [14:47] but its never going to be perfect [14:47] it gives you another dimension [14:47] i reckon mobile phoens should do this [14:47] Different places * antenna null depth * signal ratios [14:47] Action: Laurenceb is not convinced [14:47] you can massively increase the capaicty of each cell [14:47] eroomde: they sort of are. [14:48] eroomde: but only at the tower. [14:48] Laurenceb: why are you not convinced? this is how this tech works [14:48] eroomde: They segment the tower into octants or more. [14:48] 24bits is massive overkill imo [14:48] yea, they do a bit [14:48] even mil gps is only 8 bits [14:48] well, do the maths [14:48] i just have [14:48] Rejecting co-channel interference is hard. [14:48] im not convinced >8 bit is worth it [14:48] And requires everything to just work. [14:48] you want to hear something 500km at 10mW at the same time as something on 5W 1km away [14:49] so you can calc how much dynamic range on the adc that you need [14:49] yes but mismodelling [14:49] and weird second order effects etc [14:49] 24 is a lot yes, i'm not entirely serious for a first system. but 12-16 definitely. rather than 8 [14:49] you somewhat don't care about mismodeling [14:49] the MUSIC technique will never be that good [14:49]