highaltitude.log.20090817

[00:00] <SpeedEvil> you're buying a block of propellant, and making your own case+nozzle?
[00:01] <Laurenceb> yeah that was the idea
[00:07] <Laurenceb> case = off the shelf CF tube
[00:07] <Laurenceb> with some sort of liner
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[00:12] <Laurenceb> bbl
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[01:54] <SpikeUK> ! help
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[02:26] <SpeedEvil> http://www.nasa.gov/mission_pages/kepler/news/kepler-discovery.html
[02:26] <SpeedEvil> The hunt is on!
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[18:44] <DanielRichman> the Radiometrix is connected to our flight computer - but has no aerial to tx on; is it ok to switch it on?
[18:57] <SpeedEvil> yes
[18:57] <SpeedEvil> at 10mW - you won't get damage
[18:57] <SpeedEvil> read the datasheet
[18:58] <SpeedEvil> If there is any chance of damage - it'll say something like 'operating into a non ideal load may cause damage'
[18:58] <SpeedEvil> or other limitations like that
[18:58] <SpeedEvil> also - you can stick a 30cm bit of wire on it - and it'll radiate in some form
[18:59] <DanielRichman> ok, cool, thanks
[18:59] Action: DanielRichman inserts sd card and takes computer outside for a spot of testing
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[19:06] <DanielRichman> It w0rks!
[19:06] <hallam> great! what works?
[19:07] <DanielRichman> flight computer in general... though Im not too sure about the temperature readings
[19:07] <DanielRichman> but GPS, SMS, SD... all cool
[19:07] <hallam> wow, that's great
[19:07] <SpeedEvil> :)
[19:07] <hallam> what micro are you basing it around?
[19:07] <SpeedEvil> do you have a radio?
[19:07] <DanielRichman> atmega162 ('cause the 168 was out of stock)
[19:07] <SpeedEvil> I forget
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[19:08] <DanielRichman> SpeedEvil, sbasuita has Jcoxon's radio, but i'm pretty sure that works
[19:08] <DanielRichman> haven't tested the latest revision
[19:08] <neontube> evening all
[19:10] <hallam> hi neontube
[19:10] <neontube> how goes it
[19:11] Action: SpeedEvil has been developing new ways of mapping.
[19:11] <neontube> speedevil: is north now south and south now north ?
[19:11] <SpeedEvil> http://www.flickr.com/photos/14560445@N08/3826161093/
[19:12] <neontube> not sure that brick is shown on the map
[19:12] <hallam> funky
[19:13] <neontube> but that yellow B road looks hard to follow
[19:13] <hallam> is that curvilinear?
[19:13] <SpeedEvil> Got maybe 200m^3 of membrane down - as part of the massive tidying project.
[19:14] <neontube> whats going on top of the membrane ?
[19:15] <hallam> spaceship
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[19:16] <neontube> yay! just had email confirming my place on foundation radio licence course :)
[19:17] <SpeedEvil> neontube: this year - probably nothing
[19:18] <neontube> Speedevil: gravel is cheaper by the ton than in them silly bags from b&q, or wood chipings from your local tree surgen is a cheap way of doing it
[19:18] <SpeedEvil> neontube: I know - I'm looking at getting 20 tons delivered for 600 quiddish. :/
[19:19] <neontube> speedevil: not bad! all you need after that is about 30 guys around with spades and wheel barrows and a massive stash of beer as payment
[19:22] <SpeedEvil> yeah :/
[19:22] <neontube> moving 7 tons in a day of hard core for my garage floor just about killed me
[19:22] <SpeedEvil> I was thinking more moving it over several months a barrow or two a day
[19:23] <neontube> probs a good idea
[19:23] <neontube> 20+ barrows a ton
[19:23] <SpeedEvil> yeah
[19:24] <neontube> will deffinatly keep you fit :)
[19:24] <neontube> right tea time, catch you lot later
[19:25] <SpeedEvil> http://www.avant-mtc.com/500series.html I really want to help move it - but that's not looking likely :)
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[19:28] <rjharrison_home> Hi all
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[20:02] <RocketBoy> yeah - it came accross not too bad i thought
[20:02] <RocketBoy> there was masses of footage cut
[20:03] <RocketBoy> but I guess when you are trying to get it down to a few minutes for a 1/2 hour show thats what you cam expect
[20:04] <SpikeUK> RocketBoy making science simple is not easy. My 12 & 14 year old nieces watched it with me and found it interesting. But it's still not cool ;-(
[20:05] <hallam> RocketBoy, is it on iPlayer or something?
[20:05] <RocketBoy> should be I'll just check
[20:06] <rjharrison_home> Hey RocketBoy you going up soon
[20:06] <rjharrison_home> Hey bolox I missed blast
[20:06] <rjharrison_home> iplayer :)
[20:06] <RocketBoy> http://www.bbc.co.uk/iplayer/episode/b00m704v/Bang_Goes_the_Theory_Series_1_Episode_4/
[20:07] <hallam> cool, thanks, I'll check it out after work
[20:08] <DanielRichman> same. will watch it later :P
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[20:09] <RocketBoy> +8:30 in and
[20:10] <RocketBoy> and +21:30 in
[20:11] <SpeedEvil> get_iplayer is handy to download the streams.
[20:11] <SpeedEvil> Little bit of perl
[20:13] <rjharrison_home> Humm lots of BBC bolox like he's doing it
[20:17] <rjharrison_home> Hehe steve you had to run to the car
[20:18] <RocketBoy> yeah - we did that about 3 times
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[20:18] <hallam> SpeedEvil: I got some MAX2769 samples, though they won't give me the datasheet
[20:20] <SpikeUK> hallam - that's impressive! How did you manage to blag the freebies?
[20:21] <rjharrison_home> I wonder if you can decode the rtty on the program
[20:22] <rjharrison_home> Lots of mentions of space followed by a smile
[20:22] <SpeedEvil> Shiny.
[20:22] <rjharrison_home> RocketBoy Nice one. Hope no one focuses on the metion of airplanes
[20:24] <SpeedEvil> https://shop.maxim-ic.com/storefront/searchsample.do?event=Sample&menuitem=Sample&Partnumber=MAX2769ETI%2B - not really hard :)
[20:24] <SpeedEvil> Hav eyou tried the request datasheet thingy?
[20:25] <SpikeUK> Looks like that you have to apply here http://www.maxim-ic.com/req_full_ds.cfm?action=request&id=5241
[20:26] <SpikeUK> hallam - would you like me to try from my work address?
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[20:45] <Matt_APEX> http://www.spezial.com/doc/maxim/max2769.pdf
[20:45] <hallam> nah it's ok, I'll bother them
[20:45] <hallam> I don't think I'd have got the samples at all without the Joby name
[20:45] <hallam> Maxim give out a lot of their stuff easily but some special purpose chips are harder to get
[20:46] <hallam> I had tried previously for GPS front ends without much luck
[20:46] <hallam> thanks Matt_APEX, now to find the reference design...
[20:46] <Matt_APEX> ive managed to get the max2745 from them no issue
[20:48] <hallam> oh, nicely done!
[20:48] <hallam> did you build something with it?
[20:48] <Matt_APEX> na sitting in my samples box
[20:48] <Matt_APEX> it seemed like a good idea at the time
[20:49] <hallam> I have been working on a software defined GPS for a while
[20:49] <Matt_APEX> but realistically i didnt have nearly enough time to do anything with them
[20:49] <KingJ> Heya Matt
[20:49] <Matt_APEX> o hi
[20:50] <Matt_APEX> hows that going hallam?
[20:51] <hallam> it's coming along. I have a non-realtime version that works quite nicely
[20:51] <hallam> it actually runs considerably faster than realtime
[20:51] <hallam> but now I'm trying to do all the grungy stuff with data acquisition and RTOS and so on, so it can work on live data with low latency
[20:51] <hallam> taking longer than I thought
[20:52] <Matt_APEX> yea not suprised
[20:52] <hallam> I just want to get it out of the way so I can move on to trying carrier phase RTK
[20:52] <Matt_APEX> tbh im not that knowledgable on gps, which is why i never tried to do anything with those samples
[20:52] <Matt_APEX> i thought it may be a one IC solution almost
[20:53] <hallam> well it depends what you want to do with it
[20:53] <hallam> if you just want position + velocity outputs, buy a ublox
[20:54] <Matt_APEX> we've got a lassen for hte next launch
[20:54] <hallam> lassen iq?
[20:54] <Matt_APEX> yea
[20:55] <Matt_APEX> do u intend to fly ur gps?
[20:55] <hallam> definitely
[20:55] <Matt_APEX> cool
[20:55] <hallam> it won't be smaller/lighter than a ublox or lassen, and it won't really have any advantages over them for balloon applications
[20:55] <hallam> but it'll be very useful for rocket applications
[20:56] <Matt_APEX> the speed advantages?
[20:56] <hallam> it can handle high g
[20:56] <hallam> all the consumer modules keel over above ~8g
[20:56] <Matt_APEX> oh
[20:56] <hallam> I'm actually building it mainly for an autonomous kite
[20:56] <Matt_APEX> what is it thats the 'problem' with them
[20:57] <hallam> the carrier frequency changes by doppler shift too fast for the PLL to keep up
[20:57] <Matt_APEX> i would have thought it would be solid state and then no issues
[20:57] <Matt_APEX> oh ok
[20:57] <hallam> if you know what the acceleration is (i.e. accelerometer) you can compensate for it
[20:57] <Matt_APEX> i tohught u ment it broke at 8g
[20:57] <hallam> nah they just lose lock
[20:57] <Matt_APEX> ok
[20:58] <Matt_APEX> autonomous kite?
[20:59] <hallam> yes
[20:59] <Matt_APEX> mm
[20:59] <hallam> VTOL takeoff, transition to horizontal flight, crosswind figures of 8, that kind of thing
[21:00] <hallam> it needs accurate position and attitude under fairly high dynamics
[21:00] <Matt_APEX> oh ok
[21:00] <Matt_APEX> i wouldnt call that a kite tho :p
[21:00] <hallam> it's a kite because it's tethered to the ground and the tether force is what keeps it in the air
[21:01] <Matt_APEX> oh ok
[21:01] <hallam> with 3 of my receivers synchronised to each other, and the antennas at the wingtips and tail, I should be able to get attitude from GPS
[21:02] <Matt_APEX> so obviously more accurate than the standard gps?
[21:03] <hallam> with carrier phase RTK techniques you can get the relative position between antennas accurate to about a centimeter
[21:03] <hallam> and with a base station at a fixed position on the ground you can get the overall aircraft position to about 30cm
[21:04] <hallam> brb
[21:04] Nick change: hallam -> hallam|lunch
[21:04] <Matt_APEX> ok
[21:06] Nick change: hallam|lunch -> hallam
[21:07] <hallam> back
[21:07] <Matt_APEX> quick lunch :)
[21:08] <hallam> yep :)
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[21:35] <hallam> hi DanielRichman
[21:36] <DanielRichman> hi hallam
[21:36] <DanielRichman> what's up?
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[21:36] <hallam> eh, bunch of coding for gps
[21:36] <hallam> you?
[21:37] <DanielRichman> gonna make some tweaks to messages.c to make it calculate checksums correctly (well, differently, wasn;t broken just a bit wrong) and save on memory
[21:37] <DanielRichman> which gps?
[21:37] <hallam> HenryGNSS
[21:37] <DanielRichman> NMEA?
[21:38] <hallam> nope
[21:38] <DanielRichman> nom nom
[21:38] <hallam> DIY software gps
[21:38] <DanielRichman> ooooh
[21:38] <DanielRichman> that's cool
[21:38] <hallam> I'm planning to open source it and make PCBs
[21:38] <DanielRichman> nice!
[21:38] <hallam> though for regular ballooning it has no advantage over ublox
[21:38] <DanielRichman> what's the processor?
[21:39] <hallam> OMAP3530
[21:39] <DanielRichman> ARM?
[21:39] <hallam> using gumstix and beagleboard for development, haven't decided whether to use a gumstix on the production version or just build my own board
[21:39] <DanielRichman> ahh. so running linux?
[21:39] <hallam> ARM cortex a8 yeah
[21:40] <hallam> probably will be linux, though I'd rather code bare metal
[21:41] <DanielRichman> so is it a single-processor flight computer?
[21:42] <hallam> if there's CPU left over I guess it can be a flight computer
[21:42] <hallam> but it's mostly meant as a dedicated GPS
[21:42] <DanielRichman> ahh, I see
[21:42] <hallam> and IMU
[21:43] <DanielRichman> but with enough gpios, and some opensourcing, and some pinheaders on the pcbs you make, it could be a single processor flight computer
[21:43] <DanielRichman> be a bit of a shame to have an ARM doing the software gps and then an AVR to link it to the radiometrix
[21:43] <hallam> sure but one of the badgers is probably more suitable
[21:43] <DanielRichman> tru
[21:44] <hallam> it's not really meant primarily for balloon applications, so I don't want to waste board space with a radiometrix and pyro channels
[21:44] <hallam> badger 2 is intended to be that combination
[21:45] <hallam> as well as some other stuff
[21:45] <hallam> it won't be ready for a while anyway
[21:45] <DanielRichman> ahh. so will HenryGNSS have a screen, usb connection or someth?
[21:46] <hallam> no screen
[21:46] <hallam> probably serial or SPI
[21:47] <DanielRichman> or both :P
[21:47] <hallam> yeah that kind of thing isn't important and is easily changed
[21:48] <DanielRichman> might be worth putting a ftdi chip on there, since if you're making pcbs you'll want SMDs on there
[21:48] <DanielRichman> if you're selling to the average hobbyist who doesn't want to make pcbs
[21:48] <DanielRichman> FTDIs only come SMD, don't they?
[21:49] <hallam> FTDI make a nice cable that has USB on one end and a 0.1inch header on the other
[21:49] <DanielRichman> oooh, hadn't heard about that
[21:49] Action: DanielRichman likes
[21:49] <hallam> yeah they sell it on their website, I recommend owning one or two
[21:49] <hallam> this isn't for the average hobbyist
[21:50] <hallam> it's pretty special purpose
[21:50] <hallam> for most people a ublox is cheaper, smaller, lower power and faster
[21:51] <DanielRichman> this one?: http://www.ftdichip.com/Products/EvaluationKits/TTL-232R.htm
[21:51] <hallam> yep
[21:51] Action: DanielRichman notes it down; buy one
[21:52] <hallam> HenryGNSS is to compete with this kind of thing: http://cgi.ebay.com/Trimble-GPS-RTK-Complete-system-_W0QQitemZ170367923877QQcmdZViewItem
[21:52] <hallam> which it beats on all of the above criteria
[21:52] <DanielRichman> I usually end up hijacking the Arduino's ftdi chip
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[22:29] <Matt_APEX> does anyone know the two voltages to put into a radiometrix module to get the right frequency shift?
[22:30] <DanielRichman> I forget them, but I think we used ~ 0.94 and ~1.24 to get a 325 shift
[22:30] <DanielRichman> what's your supply voltage?
[22:31] <Matt_APEX> 3.3V
[22:31] <DanielRichman> k; we're on 5v so I can't help you with resistor combos. Jcoxon has a nice setup, hallam might know it
[22:31] <Matt_APEX> so its the 325 differece more important that hte absolute freqs
[22:32] <DanielRichman> I think it was GPIO -- 22k -- 2.2k -- ^to radio^ -- 22k -- GPIO
[22:32] <DanielRichman> and you alternate one high one low
[22:32] <DanielRichman> ie left high right low or right high left low.
[22:33] <DanielRichman> found his message in the logs, hangon
[22:34] <Matt_APEX> ok thanks
[22:34] <DanielRichman> incoming spam! highaltitude.log.20090426
[22:34] <DanielRichman> [12:57] <jcoxon> i've found that 2 pins with resistors on them works very well
[22:34] <DanielRichman> [12:58] <DanielRichman> resistors on the pins or potential dividers?
[22:34] <DanielRichman> [12:58] <jcoxon> 8 ------------------------------- EN
[22:34] <DanielRichman> [12:58] <jcoxon> 9 ---22K -------------\
[22:34] <DanielRichman> [12:58] <jcoxon> ---------- TX
[22:34] <DanielRichman> [12:58] <jcoxon> 10---22K -- 2K2 - 2K2-/
[22:35] <DanielRichman> [12:58] <jcoxon> GND-------------------------------GN
[22:35] <DanielRichman> [12:58] <jcoxon> 3v-------------------------------VCC
[22:35] <DanielRichman> [12:58] <jcoxon> did that come through?
[22:35] <DanielRichman> [12:58] <DanielRichman> yes
[22:35] <DanielRichman> [12:58] <DanielRichman> Oh i see
[22:35] <DanielRichman> [12:58] <DanielRichman> so it makes a potential divider between the pins
[22:35] <DanielRichman> [12:58] <jcoxon> yeah
[22:35] <DanielRichman> [12:58] <DanielRichman> because when 10 is high, 9 is grounded
[22:35] <DanielRichman> [12:58] <DanielRichman> very neat.
[22:35] <DanielRichman> [12:59] <jcoxon> those resistor values gives me nearly 425Hz shift
[22:35] <DanielRichman> [12:59] <jcoxon> so works very well
[22:35] <DanielRichman> [12:59] <DanielRichman> could just put preset pots instead
[22:35] <DanielRichman> [12:59] <jcoxon> yup
[22:35] <DanielRichman> [13:00] <jcoxon> but it works very well, rjharrison has used it to great effect as well
[22:35] <DanielRichman> ping rjharrison_home
[22:36] <hallam> One advantage of using preset pots is that you can adjust the "center" frequency as well as the spacing, which is useful when you're flying two balloons at the same time
[22:36] <DanielRichman> Boom! 150bytes of flash gone... that code sure needed a rewruite
[22:36] <hallam> you can fit several transmitters in the 434.075MHz "channel"
[22:37] <Matt_APEX> also i assume that the shift is the most important thing
[22:37] <hallam> yes
[22:37] <DanielRichman> Not having the right shift is a pain, cause fldigi has a few preset shifts
[22:37] <hallam> exactly
[22:37] <DanielRichman> you can recompile it to have a custom shift but that's a PITA
[22:37] <Matt_APEX> so if one 'voltage' could be zero it would much simplify design
[22:37] <DanielRichman> bad idea - the transmitter is centered around 1.2V
[22:37] <hallam> that doesn't work so well because the function mapping voltage to frequency isn't quite a straight line
[22:38] <rjharrison_home> Het DanielRichman
[22:38] <Matt_APEX> oh
[22:38] <DanielRichman> so 1.2V is bang in the middle of the band - carrier
[22:38] <DanielRichman> rjharrison_home, in the discussion above, "[13:00] <jcoxon> but it works very well, rjharrison has used it to great effect as well"
[22:38] <DanielRichman> is the above spam correct for Matt_APEX and 3.3V?
[22:38] <rjharrison_home> I think I was the original designer of that system :P
[22:38] <DanielRichman> :P
[22:38] <DanielRichman> what's that link to your Icarus schematic
[22:39] <hallam> if you use 0V as one of the levels you can find another voltage that will work for the other level and give the right shift, BUT it's less robust to temperature effects than a system centered around 1.2V
[22:39] <rjharrison_home> I think you can use 1 pin and 3R's but I went for a simpler option
[22:39] <rjharrison_home> but using 2 pins
[22:39] <Matt_APEX> yea i think ill have to have a play about
[22:39] <Matt_APEX> because we're not just sending out rtty, multi mode output :)
[22:41] <DanielRichman> oooh? Morse or something more interesting?
[22:41] <Matt_APEX> na afsk
[22:41] <DanielRichman> tastey
[22:41] <Matt_APEX> it means that fm -> fm transmsission works alot better
[22:42] <hallam> Matt_APEX, you'll probably be better off using a 16-bit DAC then
[22:43] <Matt_APEX> mm seems more complicated?
[22:43] <hallam> I don't see how you'll send a complex waveform into the NTX2 without a dac of some kind
[22:43] <Matt_APEX> i was going to have a stable osciallator o/p then a programmable /n thing
[22:43] <hallam> I don't quite understand
[22:43] <RocketBoy> 434mhz 10mW AFSK has a range of about 30Km with a 8ele yagi - might get a bit more with a onger yagi
[22:43] <Matt_APEX> so the serial signal changes the /n to vary the freq
[22:45] <hallam> yeah I was going to say the SNR margin of AFSK isn't going to be as good as straight FSK
[22:45] <hallam> with regular RTTY we've had 200km+
[22:45] <Matt_APEX> is that fsk picking up the signal with a ssb radio ?
[22:45] <hallam> yes
[22:46] <Matt_APEX> well u can always feed the recieved afsk into fldigi in the same way as fsk?
[22:46] <Matt_APEX> or does that form of modulation have a worse snr?
[22:46] <hallam> yes, worse snr
[22:47] <hallam> afaik
[22:47] <hallam> because you have to have a wider filter on the receiver
[22:47] <Matt_APEX> well its the best fm -> fm transmission method?
[22:47] <Matt_APEX> is that the filter which looks for the two audio tones
[22:48] <hallam> yes
[22:48] <hallam> "best" isn't very specific
[22:48] <Matt_APEX> well best range then :)?
[22:49] <Matt_APEX> anyway its going to transmit afsk and fsk so we should get hte advantages of both
[22:49] <RocketBoy> really being able to do narrow band FSK RTTY using SSB is the trick that allows us to get the distances needed for HABing using just 10mW
[22:50] <Matt_APEX> mm
[22:50] <hallam> multiple FSK schemes like dominoex can get a higher data rate at the same range or better range at the same data rate than regular RTTY, but RTTY is pretty good
[22:50] <hallam> and simple
[22:50] <hallam> I'm unclear on how AFSK is supposed to be better
[22:51] <hallam> unless you don't have an SSB receiver or something
[22:51] <Matt_APEX> yea we dont :p
[22:51] <RocketBoy> yes but can you make a workable dominoex/MFSK system using licence exempt transmitters
[22:51] <Matt_APEX> (yet)
[22:52] <RocketBoy> thats the main point - to be leagal the only thing we have easilly is LE transmitters
[22:52] <hallam> RocketBoy, I don't think anyone's flown one that works well yet, right? though both Fergus and Laurence have made progress
[22:52] <hallam> in principle it uses more of the capacity of the NTX2 + SSB receiver combination
[22:53] <hallam> Matt_APEX, I would strongly recommend getting an SSB receiver, you can probably get one for about 100 gbp
[22:53] <RocketBoy> I think I have conculeded that tha multi level stuff is a no go due to the frequency drift and change in shift with tempreture
[22:53] <Matt_APEX> we may just borrow one from a local radio society
[22:54] <Matt_APEX> has anyone tried afsk at 10mW?
[22:54] <hallam> RocketBoy, that's a pity, I'd hoped those problems could be overcome with clever receiver software (wasn't expecting it to work with the standard dominoex mode)
[22:54] <RocketBoy> it might be possible with some feedback loop - sniffing the transmitted RF and feding back to the VCO
[22:54] <hallam> or a custom transmitter with a tcxo or something
[22:55] <RocketBoy> possibly - all I'm saying is its complex and no-one has sucessfully done it yet.
[22:55] <hallam> agree
[22:55] <RocketBoy> Matt-APEX - yes we tried AFSK on the first NOVA flight
[22:56] <Matt_APEX> and not great?
[22:56] <Matt_APEX> did u use fldigi to decode?
[22:57] <RocketBoy> yes - not that great - although it packed up due to cold it was getting marginal at about 30Km
[22:57] <hallam> that was the 30km result IIRC
[22:57] <hallam> Matt_APEX, what receiver are you planning to use? please tell me not NRX2
[22:57] <RocketBoy> no it used off the shelf TNCs - which have a AFSK modem chip
[22:58] <Matt_APEX> er yea actually
[22:58] <RocketBoy> :-(
[22:58] <hallam> they are pants compared to a
[22:58] <hallam> "real" receiver
[22:58] <hallam> really not worth the effort
[22:58] <Matt_APEX> i have a handheld uhf/vhf radio too
[22:59] <RocketBoy> SSB?
[22:59] <Matt_APEX> fm only
[22:59] <Matt_APEX> ft-60
[23:00] <hallam> if you're determined not to get an SSB receiver, you could try the new 880 MHz (?) license free band which allows 500mW
[23:00] <RocketBoy> well better than the NRX2
[23:00] <hallam> that extra power might let you get acceptable range with AFSK
[23:00] <Matt_APEX> mm
[23:01] <RocketBoy> yes 868MHz 500mW AFSK whould give a usable range
[23:01] <Matt_APEX> well i think we will borrow a ssb radio
[23:01] <RocketBoy> oh well GTG - talk 2 u all anon
[23:01] <hallam> but then you wouldn't get the benefit of the ukhas distributed receiving network
[23:01] RocketBoy (n=Steve@217.47.75.8) left irc: "Leaving"
[23:01] <hallam> I think borrowing an ssb is the way to go
[23:01] <Matt_APEX> that was one of the reasons to choose 434.075
[23:02] <Matt_APEX> also going back to the previous discussion LMT2/LMR2 are supposed to be more stable
[23:05] <hallam> hm
[23:05] <hallam> maybe
[23:05] <hallam> are they similar to the NTX2 in that they give a linearish map from voltage to frequency?
[23:06] <Matt_APEX> i havnt really looked into it
[23:07] <Matt_APEX> "High performance double superhet, PLL synthesizer with TCXO"
[23:07] <hallam> yeah so I read, but it's not too obvious from that
[23:07] <hallam> at least to me
[23:07] <hallam> I'd have to study the block diagram more than I fancy doing right now
[23:08] <Matt_APEX> mm ok
[23:10] <DanielRichman> Damn... you can't use scalar initialisers for structs to assign a value later on in the code.
[23:10] <DanielRichman> or am I missing something
[23:12] <hallam> I think that's correct
[23:12] <hallam> because initialisation is pretty different to assignment
[23:12] <hallam> the initialiser reserves space in memory for the variable, and populates that memory
[23:12] <hallam> which all happens at compile / load time
[23:13] <hallam> whereas assignment is more of a dynamic process, and the assignment operator is a simple beast that can only do one thing at a time
[23:13] <DanielRichman> what a pain. I was hoping I could do that because, essentially, a macro needs to assign three values at once, and having 3 statements with semicolons inside a macro is a bit ugly
[23:13] <DanielRichman> so I made it a struct and tried to use a scalar to assign the three at once, placing the three values inside a struct
[23:14] <hallam> yeah, sorry
[23:14] <hallam> I tend to keep my macros pretty simple
[23:14] <DanielRichman> heh, guilty as charged
[23:14] <hallam> you could use the comma operator
[23:14] <DanielRichman> oh?
[23:14] <hallam> then at least it would be one statement
[23:15] <DanielRichman> oh what, "variable1, variable2 = value1, value2; "?
[23:15] <hallam> (a=3,b=4,c=5); is a valid statement
[23:15] <hallam> no
[23:15] <DanielRichman> oh right
[23:15] <DanielRichman> nice, will do that
[23:15] <DanielRichman> thanks
[23:15] <hallam> the comma operator a,b evaluates the expression a, then the expression b, and returns b
[23:16] <hallam> so d=(a=3,b=4,c=a+b); would set a to 3, b to 4, c to 7 and d to 7
[23:17] <DanielRichman> cool
[23:19] Laurenceb (n=laurence@host86-159-200-131.range86-159.btcentralplus.com) joined #highaltitude.
[23:19] <Laurenceb> hello
[23:19] <DanielRichman> hi
[23:19] <hallam> hi Laurenceb
[23:20] <rjharrison_home> ji Laurenceb
[23:20] <rjharrison_home> hi
[23:20] <hallam> Laurenceb, by any chance do you have a GN3Sv2 that I could buy from you?
[23:20] <rjharrison_home> nights
[23:20] rjharrison_home (n=rharriso@80.176.172.227) left irc:
[23:21] <Laurenceb> hallam: yeah I have one
[23:21] <hallam> I only have one, they're not making them any more, and I'm shortly to start smashing it into the ground on a regular basis
[23:21] <Laurenceb> but its kind of precious
[23:21] <Laurenceb> you can borrow it
[23:21] <hallam> ok if you're still using it then don't worry
[23:22] <hallam> I might come begging if I brake mine and haven't got my replacement design working yet
[23:22] <hallam> break*
[23:22] <Laurenceb> ok
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[23:54] <hallam> hi natrium42, ms7821
[23:55] <hallam> natrium42 what's the situation with HALO?
[23:55] <hallam> (I've been out of touch for a couple of months)
[23:56] <natrium42> jcoxon did a ballast halo flight
[23:56] <natrium42> which was longer duration latex flight
[23:57] <natrium42> but besides that, nothing else new as i have been pretty busy with work :S
[00:00] --- Tue Aug 18 2009