highaltitude.log.20170102

[00:04] <vk5hs> is any one decoding horus??
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[00:33] <vk5gr> mark are you here?
[00:34] <Darkside> yes
[00:34] <Darkside> laggy as shit at the moment
[00:34] <Darkside> muy upstream is being slammed
[00:35] <vk5gr> how do we do direct chat? cant seem to get ping to work
[00:36] <Darkside> uhm
[00:36] <Darkside> hrm
[00:36] <Darkside> ive just confirmed i can ping both payloads from here
[00:36] <Darkside> so its not a payload thing
[00:38] <Darkside> brb pit stop
[00:38] <Darkside> as soon as we find the facilities
[00:38] <vk5gr> i set a value and hit ping i should get my value back 5n the uplink parameter box
[00:38] <vk5gr> ?
[00:39] <Darkside> yes
[00:40] <Darkside> sorry, heading to the publoc loos
[00:40] <Darkside> lol
[00:40] <Darkside> when you gotta go...
[00:40] <Darkside> which payload are you trying to ping?
[01:00] <SpacenearUS> New vehicle on the map: 03VK5ZM-9_chase - 12https://tracker.habhub.org/#!qm=All&q=VK5ZM-9_chase
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[04:20] <SpacenearUS> New vehicle on the map: 03RIA-20 - 12https://tracker.habhub.org/#!qm=All&q=RIA-20
[05:46] <SpacenearUS> New position from 03XX after 033 days silence - 12https://tracker.habhub.org/#!qm=All&q=XX
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[06:23] <SpacenearUS> New vehicle on the map: 03BLAHCOUL01 - 12https://tracker.habhub.org/#!qm=All&q=BLAHCOUL01
[06:38] <SpacenearUS> New vehicle on the map: 03BLAHCOUL02 - 12https://tracker.habhub.org/#!qm=All&q=BLAHCOUL02
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[06:54] <SpacenearUS> New vehicle on the map: 03BLAHCOUL02 - 12https://tracker.habhub.org/#!qm=All&q=BLAHCOUL02
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[07:16] <SpacenearUS> New vehicle on the map: 03BLAHCOUL02 - 12https://tracker.habhub.org/#!qm=All&q=BLAHCOUL02
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[07:21] <SpacenearUS> New vehicle on the map: 03BLAHCOUL02 - 12https://tracker.habhub.org/#!qm=All&q=BLAHCOUL02
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[07:39] <SpacenearUS> New vehicle on the map: 03TA2MUN-11 - 12https://tracker.habhub.org/#!qm=All&q=TA2MUN-11
[07:41] <SpacenearUS> New vehicle on the map: 03BLAHCOUL02 - 12https://tracker.habhub.org/#!qm=All&q=BLAHCOUL02
[07:50] <iain_> While testing a HAB setup and not doing a real flight is there any convention on labelling settings as a test ?
[07:51] <SpacenearUS> New vehicle on the map: 03BLAHCOUL02 - 12https://tracker.habhub.org/#!qm=All&q=BLAHCOUL02
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[08:06] <Ian_> Not really as your callsignID will want to be the same as the flight otherwise a change could be where an error creeps in
[08:06] <SpacenearUS> New vehicle on the map: 03BLAHCOUL02 - 12https://tracker.habhub.org/#!qm=All&q=BLAHCOUL02
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[09:05] <Vaizki> someone blackhole blahcoul :)
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[09:45] <pb0ahx> GM all Happy newyear
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[11:28] <SpacenearUS> New position from 03K6RPT-11 after 032 days silence - 12https://tracker.habhub.org/#!qm=All&q=K6RPT-11
[11:40] <SpacenearUS> New position from 03RSIST after 03a day silence - 12https://tracker.habhub.org/#!qm=All&q=RSIST
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[13:42] <SV3ISZ_Vasilis> Waiting for TA2MUN-11......
[14:18] <SpacenearUS> New position from 03UBSEDS21 after 0314 hours silence - 12https://tracker.habhub.org/#!qm=All&q=UBSEDS21
[14:21] <russss> http://www.spacex.com/news/2016/09/01/anomaly-updates
[14:21] <SpacenearUS> New vehicle on the map: 03220720_chase - 12https://tracker.habhub.org/#!qm=All&q=220720_chase
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[14:32] <adamgreig> russss: honestly I'm disappointed it wasn't the gunman scenario
[14:34] <russss> heh
[14:38] <fsphil> cover-up
[14:38] <fsphil> (shouldn't joke, some people believe this crap)
[14:42] <daveake> It was shot by Elvis to prevent discovery of the Earth being flat
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[15:25] <Geoff-G8DHE-Lap> :-) Improved version it now descends by parachute! https://www.youtube.com/watch?v=TuJXax0hh8I
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[15:59] <matb> I was going to put AB12 in the loft once it was working well (which it is, it's my other nodes that are rubbish). Less chance of me tripping over it for a start. Either that or in a box in the open, but I've less chance of getting a good unidirectional signal other than in the loft
[15:59] <matb> oops. wrong channel. finger trouble
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[16:25] <SpacenearUS> New vehicle on the map: 036 c y uh i_chase - 12https://tracker.habhub.org/#!qm=All&q=6%20c%20y%20uh%20i_chase
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[16:27] <Laurenceb_> does anyone here have experience with ntpd?
[16:28] Action: Laurenceb_ is wondering what sort of round trip time statistics are best for optimal performance
[16:29] <Laurenceb_> some ntp servers are very fast but with occasional huge delays, whereas some are a bit slower but more reliable
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[16:33] <russss> NTP is pretty good at making that decision itself
[16:33] <russss> if you give it 5+ servers it'll select the best one to prefer
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[16:33] <Laurenceb_> ah
[16:34] <Laurenceb_> can it filter out occasional huge round trip times?
[16:34] <russss> yes
[16:34] <Laurenceb_> ah cool
[16:35] <russss> I think it will generally prefer the servers which have lower jitter
[16:35] <Laurenceb_> ntp0.sandvika.net is giving me the best results so far...
[16:35] <Laurenceb_> ok
[16:35] <adamgreig> you should probably just use a suitable pool hostname though
[16:35] <Laurenceb_> 17ms RTT, far better than I expected
[16:35] <Laurenceb_> ok
[16:36] <adamgreig> uk.pool.ntp.org or similar
[16:36] <Laurenceb_> I only need to synchronise to <10ms absolute error
[16:36] <Laurenceb_> so it already looks easily doable
[16:36] <adamgreig> http://www.pool.ntp.org/zone/uk
[16:36] <Laurenceb_> I thought this would be much harder :P
[16:36] <adamgreig> oh yea sure
[16:36] <craag> newer ntpd versions you can give a pool hostname, and it'll resolve several servers out of it, cycling out servers it rejects I believe.
[16:36] <Laurenceb_> ok
[16:37] <Laurenceb_> havent played with ntpd yet, was just manually pinging to check feasilbility of the idea
[16:37] <Laurenceb_> I canna spell
[16:37] <craag> 10ms should be very easy.
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[16:38] <adamgreig> yea
[16:39] <russss> yeah <10ms is fine
[16:39] <Laurenceb_> cool
[16:39] <Laurenceb_> geographic location doesnt seem to effect RTT much
[16:39] <russss> and I think the source of that error is primarily network jitter rather than absolute latency (which NTP does correct for)
[16:39] <Laurenceb_> local uni ntp servers are slightly slower
[16:39] <russss> although latency is a good proxy for jitter.
[16:40] <Laurenceb_> but they have lower jitter
[16:40] <Laurenceb_> v interesting
[16:40] <SpacenearUS> New position from 03WB8ELK-2 after 0320 hours silence - 12https://tracker.habhub.org/#!qm=All&q=WB8ELK-2
[16:40] <russss> on an uncongested gigabit network I think you can get down to <0.1ms error
[16:40] <russss> assuming you have a good enough time source
[16:41] <Laurenceb_> I'm just wifi -> ADSL lol
[16:41] <Laurenceb_> would ethernet -> ADSL improve things?
[16:42] <russss> yeah, wifi is a fairly significant source of jitter
[16:43] <Laurenceb_> cool
[16:43] <Laurenceb_> I was reading reports of people having about 5ms or so of absolute error over ADSL due to asymmetric delays
[16:43] <Laurenceb_> but that was with RTT of >200ms
[16:43] <Laurenceb_> so just scaling the results suggests I'm get <1ms absolute error
[16:44] <Laurenceb_> they were on Italian ADSL iirc :P
[17:17] <SpacenearUS> New position from 03HIRFW-6 after 0315 hours silence - 12https://tracker.habhub.org/#!qm=All&q=HIRFW-6
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[18:40] <jcoxon> hey all, quick question, i need to run some cpu intensive stuff on a virtual machine - any suggestions that aren't AWS
[18:41] <SpeedEvil> ##raspberrypi
[18:41] <SpeedEvil> (kidding)
[18:42] <SpeedEvil> Need cheaper than AWS, or don't trust?
[18:43] <russss> I like digitalocean
[18:43] <jcoxon> had to close my amazon account due to hackers
[18:43] <craag> linode
[18:43] <jcoxon> so they think its suspended
[18:43] <jcoxon> (someone kindly tried to order a ps4 and iphone 7for me)
[18:44] <craag> or there's google's aws-equivalent, haven't tried them myself though
[18:44] <jcoxon> the google one wanted a businees name
[18:45] <craag> ah
[18:45] <craag> digitalocean / linode then
[18:46] <russss> Google cloud platform is decent as well
[18:46] <russss> but my go-to is digitalocean
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[18:50] <adamgreig> it's really annoying how google cloud needs a business and won't deal with consumers
[18:50] <adamgreig> presumably because cba with tax
[18:51] <SpeedEvil> For what level of 'needs a buisness' - making up a name satisfies lots.
[18:51] <adamgreig> VAT ID
[18:51] <SpeedEvil> But yes, if the T&Cs say it's b2b onlym, and you need it to stay up, probably not a good idea
[18:51] <SpeedEvil> ah
[18:51] <adamgreig> seems a great way to put off loads of developers though
[18:51] <SpeedEvil> Do small buisnessses under the VAT threshold have VAT numbers?
[18:51] <adamgreig> shrug
[18:51] <SpeedEvil> I don't think they do
[18:52] <adamgreig> hmm I might be misremembering
[18:52] <adamgreig> let's see again
[18:52] <SpeedEvil> 81K turnover is quite a limit of buisnesses you don't care about
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[18:54] <adamgreig> well, the VAT number is indeed optional
[18:54] <adamgreig> wonder what they want then
[18:54] <adamgreig> I seem to remember being literally unable to sign up previously
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[18:59] <adamgreig> Google Cloud Platform services can be used only for business purposes in the European Union. If the sole purpose for which you want to use Google Cloud Platform services has no potential economic benefit you should discontinue your use of the service.
[18:59] <adamgreig> https://support.google.com/cloud/answer/6090602
[19:00] <adamgreig> suspect maybe you could just use it anyway or whatever
[19:00] <Ian_> Only get a VAT number if you are registered for VAT. Sole Trader has no business number either, but some businesses insist on a registered ltd/llc etc.
[19:01] <Ian_> Potential economic benefit - interesting; depends on the point of view I guess.
[19:02] <Ian_> Lifestyle business model.
[19:06] <jcoxon> digitalocean was nice and easy
[19:06] <jcoxon> good to know
[19:06] <russss> hmm yes, I remember some faff signing up, but I didn't need a VAT number
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[19:12] Action: jcoxon is back to trying to crack his old bitcoin wallet password
[19:12] <jcoxon> 0.4btc is worthwhile again
[19:15] <fsphil> I got £1-worth of bitcoin about 3 years ago at an event, worth £2 now
[19:15] <fsphil> I've no idea what to do with it :)
[19:15] <SpacenearUS> New vehicle on the map: 03savuzwa_chase - 12https://tracker.habhub.org/#!qm=All&q=savuzwa_chase
[19:16] <jcoxon> they say it will increase in price further...
[19:16] <jcoxon> or you could sell it and use it :-)
[19:16] <fsphil> I'm not even sure I know how to
[19:16] <jcoxon> i've got this: https://xapo.com/card/
[19:16] <jcoxon> and use it day to day
[19:18] <SpacenearUS> New vehicle on the map: 03car_chase - 12https://tracker.habhub.org/#!qm=All&q=car_chase
[19:19] <jcoxon> fsphil, i did 3 weeks of pretty much only spending bitcoin
[19:20] <fsphil> nice. I guess now would be a good time to get some more
[19:21] <jcoxon> i not sure right now is a good time
[19:21] <jcoxon> but thats a discussion for off topic :-)
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[19:29] <jcoxon> russss, you should have referred me to digital ocean
[19:29] <jcoxon> and you would have got credit
[19:29] <jcoxon> sorry!
[19:40] <PE2BZ> Hello, off topic question, if in the UK you have a company car and you drive privately and you have to keep administration of the distances you drive, how do they call that in England ?
[19:41] <azstefano> Im decoding a balloon on WSPR approaching So. Cal. from the pacific&but instead of the callsign Im getting the alternate data: QJ2XXE, QS2WWH, QS2VVH, QS2FVH& Habhub confirms it as HIRFW&
[19:41] <jcoxon> you usually submit your mileage
[19:42] <jcoxon> azstefano, yeah so its a workaround to submit the data on the WSPR network
[19:43] <azstefano> Yes - its clever on a good mode with limited options&
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[19:43] <OZ1SKY_Brian> Hi and HNY everyone
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[19:44] <fsphil> Darkside: good images from yesterday. the high speed mode is working well now
[19:47] <PE2BZ> jcoxon that´s right, but I need some automation for that. So I was hunting Ebay for hardware but I have no clue how it´s called in England.
[19:48] <Reb-SM0ULC> fsphil: possible to use quite bitcoin at a lot of tech-shops in sweden
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[19:48] <fsphil> how? phone app?
[19:50] <Reb-SM0ULC> fsphil: via bitpay etc
[19:50] <fsphil> ah
[19:50] <aadamson> azstefano, that's hirfw-6 (callsign k4mea on WSPR), and those Q calls are it's telemetry
[19:51] <aadamson> it uses 2 WSPR spots one, it normal with altitude in 1000's of meters for the dbm, the other is all telemetry coded in WSPR except for the 4 digit grid square it matches it's location and the earlier WSPR spot
[19:52] <gurlavie_> Hi Guys, a quick question about the Payload document and Flight document methodology. So I have a PITS board with Lora and RTTY, and a HabDuino with APRS - I am re-using them across missions (if not loosing them). What is the right way to define them in a way that I can simply reuse across flight documents ?
[19:55] <daveake> Nothing special. You can re-use the payload docs. For the flight doc, create a new one based on the previous one, change the date, job done.
[19:55] <daveake> This ofc assumes that nothing has changed - frequency, sentence structure etc
[19:56] <azstefano> aadamson: thanks. Signal is respectable - about 15dB above my noise floor. In phoenix I should be able to hear it line-of-sight in a few hours - that will be a treat.
[19:58] <aadamson> azstefano, it's only around 10mW (maybe 12, but no more) :)
[20:01] <Reb-SM0ULC> adamgreig: you use same encodieng as Dave?
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[20:05] <azstefano> aadamson - is there a URL where you have defined the telemetry? Also, I noticed that both you and Bill have spots on wsprnet that decode, in your case, as 200W TX and for Bill as 10 watts. That must be part of your telemetry mod to get more parameters in& 10mW coming in great today&after six passes - wow.
[20:09] <aadamson> Bill uses something close to mine, but a little different. And yes, that TX power will never be correct for either he or I, that field of data in the main WSPR spot is our altitude in 1000's of meters (but it has to be encoded in dbm steps e.g. 0, 3, 7, 10, ... etc
[20:09] <fsphil> has anyone chatted with the wspr folk about adding a proper altitude field?
[20:11] <aadamson> fsphil, the problem with WSPR is that it's an extremely limited protocol (encoding) to continue to use the WW RX network it will have to follow the original guidelines. We got lucking in finding that there are no callsigns issues in the world that start with Q, which allowed us to use that for telemetry
[20:11] <aadamson> as long as the rest of the packet was in WSPR format
[20:11] <aadamson> azstefano, https://dl.dropboxusercontent.com/u/6730484/WSPR%20Telem.xlsx
[20:13] <aadamson> fsphil, - http://www.g4jnt.com/wspr_coding_process.pdf
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[20:13] <aadamson> no way to change that without breaking everything else unfortunately
[20:15] <azstefano> Thanks Alan - Ill check it out.
[20:16] <aadamson> azstefano, with that you can put in both the main and the telemetry spot and it will give you the telemetry and the 6 digit grid
[20:17] <gurlavie_> aadamson - great wspr links - was just wondering if such exist. Thanks !
[20:17] <gurlavie_> Thanks Dave. Will do that.
[20:19] <azstefano> Im NU7B in the spots. HIRFW might be entering my skip zone - should emerge as line of sight north of me over Prescott, AZ.
[20:20] <aadamson> yeah, looks like it's about midday at it's location so it will have 4hrs or so of daylight
[20:20] <aadamson> today I push to APRS.si, which is picked up by aprs.fi and replicated via habhubs tracker
[20:21] <aadamson> my text WSPR flight will push directly to habitat/habhub tracker. It's simply a better mousetrap with it's integrated hysplit support, etc
[20:22] <azstefano> Is it APRS on VHF?
[20:22] <aadamson> plus you can get things like total distance and duration. I always have to count laps manually... think -6 is on 7 about to finish 7 and start 8
[20:22] <aadamson> it has 2 radios, the other is on geofenced APRS WW, so yeah, you'll hear it on 144.390 as well in the US
[20:23] <aadamson> What's always fun is to put hirf-6; hirfw-6 in the habhub tracker's search and then select "ALL" as the duration, you'll see how grossly limited APRS is for WWW tracking
[20:24] <aadamson> s/WWW/WW :)
[20:25] <azstefano> I have APRS on a new HT I have - it may decode on the screen - I honestly havent explored that mode except for trying it once. Ill fire it up&
[20:26] <aadamson> at some point, probably today hirf-6 will *catch up* on the maps...
[20:26] <aadamson> azstefano, ot
[20:27] <aadamson> it's a little tiny thing - https://dl.dropboxusercontent.com/u/6730484/2016-05-02%2020.50.12%20-%20small.jpg board weight ~ 1gr
[20:27] <aadamson> all up in flight condition it's ~7g - https://dl.dropboxusercontent.com/u/6730484/2016-04-07%2022.11.58%20-%20small.jpg
[20:31] <azstefano> aadamson - Beautiful piece of work - hats off to you. Looks like the resonator is TCXO? Amazing you have it going down to -60 C. I notive that Bills frequencies are pretty stable - pretty important for wspr.
[20:31] <aadamson> yes, in that case it's a VCTCXO as I make AFSK via true FM
[20:36] <Reb-SM0ULC> adamgreig: what for the future? go to jt9?
[20:36] <adamgreig> think you mean aadamson
[20:36] <Reb-SM0ULC> sri!
[20:37] <aadamson> Reb-SM0ULC, who knows.. I have JT9, JT65 and WSPR code functional, but neither of those have WW RX networks.
[20:40] <Laurenceb_> VCTCXO as I make AFSK via true FM
[20:40] <Laurenceb_> sounds tricky
[20:41] <Laurenceb_> isnt the voltage sensitivity temperature sensitive?
[20:41] <aadamson> hasn't been a problem, I've done it on all of my designs so far, K6RPT is flying it on my old design
[20:42] <aadamson> it's a 1.8v LDO driving the TCXO, and DAC driving the VC input on it
[20:42] <Laurenceb_> https://dl.dropboxusercontent.com/u/6730484/2016-05-02%2020.50.12%20-%20small.jpg
[20:42] <Laurenceb_> silabs?
[20:43] <aadamson> yup
[20:43] <aadamson> *both* :)
[20:43] <Laurenceb_> and SAW filter?!
[20:43] <aadamson> no saw filter?
[20:43] <aadamson> minicircuit lpf
[20:44] <aadamson> saved a whole filter chain
[20:44] <Laurenceb_> oh sweet
[20:45] <Laurenceb_> whats the 5351? IC?
[20:45] <aadamson> si5351 2.5khz to 300mhz clock with 50 ohm outputs :)
[20:45] <aadamson> multi clock that is
[20:46] <aadamson> and yes, technically I could do APRS on 2mtrs with it as well, but don't
[20:46] <Laurenceb_> interesting approach
[20:46] <aadamson> due to the antenna
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[21:15] <SpacenearUS> New position from 03HIRF-6 after 033 days silence - 12https://tracker.habhub.org/#!qm=All&q=HIRF-6
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[21:42] <gurlavie_> aadamson: do you protect it in any way ?
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[21:42] <gurlavie_> I mean against the weather....
[21:43] <aadamson> nope, it's flying *naked* all of them have
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[21:45] <gurlavie_> Amazing.....I should "hopefully" send one of Bill's tracker this Thursday from Israel. Part of a class project of HAB. Should be the first floater out from Israel AFAIK.
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[21:46] <aadamson> ah very nice... good luck with that. On WSPR or just his APRS one?
[21:48] <gurlavie_> APRS for this one, I think only because this is what I knew originally and what I have for the short hours it will be under our coverage. After tracking your floaters for a while I guess this was a mistake. Should have done WSPR.
[21:48] <aadamson> hehe ya need to start somewhere :)... on what balloon? 1 mtr party?
[21:50] <jcoxon> gurlavie_, don't worry APRS can work for you as well, lots of the early round-the-world floaters just used aprs
[21:50] <aadamson> yep indeed ^^^
[21:51] <gurlavie_> yes, another bummer. I don't feel confident to get the school invest in the top quality balloons you are using - for the first time. If this will get the kids interested, next launch can be with the high quality.
[21:51] <jcoxon> it would be nice if we could setup some aprs listening stations in some of the gaps
[21:51] <jcoxon> such as India
[21:52] <aadamson> jcoxon, wb8elk has been working on that, he got a couple of people, one in that area, and one in mongolia I think to setup gateways, but that is somewhat harder than it needs to be
[21:53] <jcoxon> yeah i'm sure
[21:53] <jcoxon> there is a lot of psychology about this
[21:54] <aadamson> not sure about that part, but the setting up of direwolf or soundmodem, while if youve done it is really easy
[21:54] <aadamson> can be daunting for those who haven't
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[21:54] <aadamson> *and* interfacing a radio to it
[21:54] <jcoxon> also if there isn't anything to listen to at that exact point interest can wane
[21:54] <aadamson> exactly
[21:54] <jcoxon> e.g. there is no APRS activity in my area
[21:55] <gurlavie_> by the way, what should I expect to be the life time with a "party balloon" ? have they ever completed a full round ? probably winter isn't a good time for a "simple" launch ?
[21:55] <jcoxon> gurlavie_, they have done a few days but i don't think they've managed a complete circle without some modifications
[21:55] <aadamson> can you do H2 or will have have to do HE?
[21:55] <daveake> I've run my pi igate for 3 days. 1wx and 1 car so far
[21:56] <aadamson> I think Andy got one around on H2
[21:56] <aadamson> you really need to get up to around 12km if possible
[21:56] <aadamson> higher is better, which means light payload and H2 usually on a 1 mtr party
[21:56] <aadamson> or should I say *extremely light* payload :)
[21:57] <gurlavie_> Good point. Theoretically, I can, but if I want students to do the inflation and launch, I might get into trouble. Are there larger miller balloons I can use to get higher ?
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[21:58] <aadamson> you can split the freelift, and use 2 parties
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[21:58] <aadamson> what has been done so far is some info here I think (looking for a link)
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[21:59] <jcoxon> i found 2 balloons difficult to get right
[21:59] <aadamson> gurlavie_, look through Mikes blog, and Daves flights (both are using 2 metalized balloon).
[21:59] <jcoxon> if one is filled more then the other it can lift it too high and the other will burst
[21:59] <gurlavie_> I can certainly ! Great point ! I am thinking Latex...no 2 balloons...So would you suggest "simply" use two ballons ? Is there any calculator for this ?
[21:59] <gurlavie_> jcoxon - how so ?
[21:59] <aadamson> They are attached in tandem and the freelift is split between the two
[22:00] <aadamson> http://qrp-labs.com/ultimate3/ve3kcl-balloons.html
[22:00] <gurlavie_> -- I guess one can become a drag instead of a lift ?
[22:00] <aadamson> That is the risk
[22:00] <gurlavie_> Will read through - thanks !
[22:00] <aadamson> if one has a leak, it's coming down
[22:00] <aadamson> you are looking for around 5-6gr free with 2 or around 3gr with one
[22:01] <aadamson> and as I say... if a bird poops on it, it's coming down :).
[22:02] <gurlavie_> :) or too much rain....ice...
[22:05] <daveake> magnetic tree
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[22:26] <Laurenceb_> damn ntpd is good
[22:26] <Laurenceb_> about 100µs error over ADSL and wifi
[22:26] <Laurenceb_> hmmmm......
[22:27] <Laurenceb_> this is good enough 4 interferometry
[22:31] <Laurenceb_> we could run a network of base stations for locating dumb trackers
[22:32] <adamgreig> might as well just give them GPS since you want accurate position anyway
[22:32] <adamgreig> and then you get much better time sync
[22:32] <adamgreig> ntp doesn't really solve an issue
[22:33] <Laurenceb_> well most SDRs use a single xtal for samples and LO
[22:33] <Laurenceb_> so you can discipline everything in software
[22:33] <Laurenceb_> no need for custom hardware
[22:33] <adamgreig> even then, a usb gps puck is cheap and gives position and very accurate timing
[22:34] <Laurenceb_> base station becomes SDR + python (or whatever) application
[22:34] <Laurenceb_> yes
[22:35] <Laurenceb_> anyone here ever used airspy with python?
[22:35] <Laurenceb_> I'm assuming there is a library lol
[22:41] <Darkside> hm
[22:41] <Darkside> im sure you gould get blocks of samples
[22:41] <Darkside> i guess if you offload enough stuff to other C Libs you might be able to progess a few mhx in realtime
[22:41] <Darkside> mhz*
[22:42] <gurlavie_> Any recommended reference for payload document for the LORA- Telemetry payload ?
[22:43] <Darkside> probably a daveake question
[22:44] <daveake> erm, just use same as rtty and remove the rtty part
[22:45] <Laurenceb_> guess I could modify https://github.com/airspy/host/blob/master/airspy-tools/src/airspy_rx.c
[22:45] <Laurenceb_> prob the simplest way to do this
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[22:47] <Laurenceb_> add a third channel with time in it, nasty but simple :D
[22:49] <Darkside> Laurenceb_: oh are you thinking of using the spare ADC on the airspy?
[22:49] <Darkside> im interested in that too
[22:49] <Darkside> i'd like to sample a 360 degree potentiometer at the same time as sampling RF
[22:49] <Darkside> and put the antenna on a spinning mount
[22:50] <Laurenceb_> no
[22:50] <Laurenceb_> but nice idea
[22:51] <Laurenceb_> just ntpd and airspy, no hardware mods
[22:51] <Darkside> hrm
[22:51] <Darkside> doesnt this assume the usb delay is constant?
[22:51] <Laurenceb_> yes
[22:51] <Darkside> is it?
[22:52] <Laurenceb_> should be fairly
[22:52] <Laurenceb_> I'd guess jitter is down to a few samples
[22:52] <Darkside> i would have though some kind of in-band signal or timestamping occuring in the radio was essential to this
[22:52] <Laurenceb_> I dont have my airspy here or I'd test :-/
[22:52] <Darkside> at least being able to trigger sampling off some kind of external trigger
[22:53] <Laurenceb_> theres lots of opportunity to clean things up with averaging if you only want rough location
[22:53] <Darkside> which could just be 1PPS
[22:53] <Laurenceb_> to like a few km
[22:53] <Darkside> mm 300m/uS
[22:53] <Darkside> so you need to be within a few uS
[22:54] <Laurenceb_> you can live with more alignment error with the right processing technique
[22:55] <Laurenceb_> in fact for balloons you can live with much more
[22:55] <Laurenceb_> maybe a millisecond or two
[22:56] <Laurenceb_> for balloons the tricky thing is LO drift over the timescale of an hour or so
[22:56] <SpeedEvil> Two balloons at once helps :)
[22:56] <Laurenceb_> I think, I've only run detailed sims of this for rockets so far
[22:57] <Laurenceb_> its going to depend on the quality of the clock on the pc
[22:57] <Laurenceb_> mine seems v good with is helping me
[22:58] <Laurenceb_> +-5ppb drift over the past 3 hours
[22:58] <adamgreig> what're you measuring it with?
[22:58] <Laurenceb_> reported by ntpd with verbose logging
[22:58] <Reb-SM0ULC> PTP ftw ;)
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[23:00] <Laurenceb_> using Stratum1 NTP server
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[23:01] <Darkside> im looking forward to when the kiwisdr network can do TDOA stuff
[23:01] <Laurenceb_> https://www.youtube.com/watch?v=JmpiJeNffuU
[23:01] <Darkside> given theres so many kiwisdrs out there, alll of which can be synced to GPS
[23:01] <Darkside> its going to form a massive worldwide TDOA network
[23:02] <Laurenceb_> doppler difference is much easier
[23:02] <Laurenceb_> and balloons are usually moving :P
[23:03] <Darkside> oh you're using doppler!
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[23:03] <Darkside> jeez its going to be small isnt it
[23:03] <Darkside> well, it might be
[23:04] <Darkside> and its going to require the SDRs to be locked to a decent reference
[23:04] <Laurenceb_> few hundred ppb
[23:04] <Darkside> (so GPS i guess)
[23:04] <Laurenceb_> - the doppler
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[23:05] <Laurenceb_> well thats what I thought before I saw what can be achieved with ntpd
[23:05] <Darkside> uh
[23:05] <Darkside> im talking about absolute frequency measurement here
[23:05] <Laurenceb_> yeah
[23:06] <Laurenceb_> on something like airspy the sample clock is shared with LO
[23:06] <Laurenceb_> its all off a single TCXO
[23:06] <Darkside> sure
[23:06] <Darkside> and that needs to be locked to a common reference to be useful, right?
[23:06] <Darkside> im talking about across multiple stations here
[23:06] <Laurenceb_> so (lame hack level) you stick an extra channel in the wav recorder
[23:06] <Darkside> surely adding a 10mhz reference isnt that hard
[23:06] <Laurenceb_> then in the rx_callback function you write the system time
[23:07] <Laurenceb_> I've got a fetish for making it software only
[23:07] <Darkside> not everything can be solved in software
[23:07] <Laurenceb_> so a distributed network is simple
[23:07] <Darkside> for doppler dont you care about knowing what the exact frequecy of the payload signal is?
[23:07] <Darkside> how good is the TXCO compared to the expected doppler?
[23:08] <Darkside> hrm
[23:08] <Darkside> even the ppm on the TCXO wont tell you how close they are between units
[23:08] <Laurenceb_> well after about 30 seconds of stabilisation my clock is very stable
[23:08] <Darkside> yes but surely the point here is has to be stable between multiple distance units, right?
[23:09] <Laurenceb_> +-5ppb drift over the past 3 hours
[23:09] <Laurenceb_> yes
[23:09] <Laurenceb_> 5ppb is about 1% of the typical dopplers for a balloon
[23:10] <Darkside> so are you trying to look at the relative frequency difference as obsered at multiple stations?
[23:10] <Laurenceb_> so it could probably be poss to solve for location to a few km error
[23:10] <Laurenceb_> yes
[23:10] <Darkside> ok
[23:10] <Darkside> so that means you need each station to have its LO locked to a common reference
[23:10] <Darkside> or you need a known reference signal within the passband
[23:10] <Darkside> which is unlikely
[23:11] <adamgreig> unless he's also estimating the tcxo offset on each airspy
[23:11] <Laurenceb_> no
[23:11] <Darkside> adamgreig: and how the hell is he doing that?
[23:11] <Laurenceb_> you can estimate the offset
[23:11] <Laurenceb_> what adamgreig said
[23:11] <Darkside> to what?
[23:11] <adamgreig> the balloon presumably
[23:11] <Laurenceb_> to PC system time
[23:11] <adamgreig> long term
[23:11] <adamgreig> oh what
[23:11] <Darkside> im still not sure how system time helps with this
[23:11] <adamgreig> how do you plan to do it to system time?
[23:11] <Laurenceb_> https://github.com/airspy/host/blob/master/airspy-tools/src/airspy_rx.c
[23:11] <Darkside> the airspy has a 10mhz input ffs
[23:11] <adamgreig> I guess over a minute you can see how many samples the tcxo sent
[23:12] <Darkside> adamgreig: that makes assumptions about USB transfer right?
[23:12] <adamgreig> and that gives you the tcxo frequency compared to system clock
[23:12] <adamgreig> nah
[23:12] <Laurenceb_> lame hack approach would be stick it arounf line 365
[23:12] <adamgreig> the airspy hardware generates (TCXO freq / X) samples per second, right
[23:12] <adamgreig> and all those samples go over USB
[23:12] <adamgreig> oh well
[23:12] <Darkside> the airpy has a 10mhz input. it was designed for this kin dof stuff
[23:12] <Laurenceb_> yeah
[23:12] <Darkside> put a fucking 10mhz gps reference into it
[23:12] <Darkside> and you are done
[23:12] <adamgreig> it depends on USB jitter, but you can get rid of that over sufficiently long time periods
[23:12] <adamgreig> Darkside: yea I agree with you here
[23:12] <Darkside> im sure leo can help you out
[23:13] <Laurenceb_> Darkside: I'm thinking for cheap simple distributed listeners
[23:13] <adamgreig> but in principle, count samples received over one hour of system time, and you can esimtate the TCXO freq
[23:13] <Darkside> som of the u blox chips can do 10mhz out
[23:13] <Laurenceb_> need to try ntpd on raspberry pi
[23:13] <Darkside> i think the jitter is bad tho
[23:13] <Laurenceb_> jitter isnt that much of a problem over ~1 hour timescales
[23:13] <adamgreig> the issue is your system time will be worse tha your TCXO probably
[23:13] <Darkside> i think my problem here is that i've been doing this kind of thing in acual operational systems
[23:13] <adamgreig> your hope is that ntpd will correct for local clock drift well enough
[23:13] <Laurenceb_> well I'm on a half decent thinkpad here
[23:14] <adamgreig> even a half decent thinkpad is unlikely to have a particularly good timekeeping crystal
[23:14] <Darkside> and hearing about trying to do it without a decent reference makes my brain hurt
[23:14] <Laurenceb_> rpi will probably have worse allen variance and drift
[23:14] <adamgreig> certainly compared to a tcxo in the airspy
[23:14] <adamgreig> the airspy will be more stable and more accurate i should think
[23:14] <adamgreig> but your system time has the advantage of ntp
[23:14] <Laurenceb_> well as long as the usb jitter isnt horrific then airspy is irrelevant
[23:14] <Laurenceb_> oh wait
[23:15] <Laurenceb_> no you can Kalman filter system time and Airspy time
[23:15] <Laurenceb_> that would be optimal
[23:15] <adamgreig> if you're doing 1Ms/s then over an hour that's nominal 3.6B samples, 1ppm error in tcxo shows up as 3600 extra samples
[23:15] <Laurenceb_> Kalman to the rescue (as is the case in most problems)
[23:16] <adamgreig> but your computer clock is NTP to within 1ms which is 1000 samples so..
[23:16] <adamgreig> it doesn't work out that well
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[23:16] <adamgreig> I think you're mistaken to assume you can get a few ppb local clock stability from ntp
[23:16] <russss> Laurenceb_: http://www.rtklib.com/
[23:16] <adamgreig> lol yea
[23:17] <adamgreig> just use the airspy to listen to gps for a bit
[23:17] <adamgreig> some issues with antennas
[23:17] <Laurenceb_> adamgreig: ntpd is reporting I do have that kind of stability
[23:18] <Laurenceb_> and the raw errors seem to confirm it
[23:18] <Darkside> adamgreig: could use GSM or 4G
[23:18] <Laurenceb_> havent had an error over 500µs for two hours
[23:18] <Darkside> there some calibration apps that use LTE signals i think
[23:18] <adamgreig> yea bladerf has a nice gsm/lte calibration thing
[23:18] <Darkside> you'd have to do regular calibration i expect
[23:19] <russss> I think you can improve the time solution if you have a reasonably well-fixed position solution
[23:19] <russss> this gets a bit silly at this point, but I've been looking into low-cost high-accuracy GPS systems
[23:19] <Laurenceb_> russss: and use https://en.wikipedia.org/wiki/Alpha_beta_filter
[23:20] <Laurenceb_> well this is all a bit silly for balloons
[23:20] <Laurenceb_> maybe for bird tracking of something
[23:20] <russss> AIUI the good GPS receivers are able to export the signal phase for further processing, plus you also end up with antennas with well-characterised response
[23:21] <russss> however
[23:22] <russss> if you just want good time performance then I think any old GPS receiver combined with an [OT]CXO will give you something pretty great
[23:22] <Laurenceb_> russss: like this https://store.uputronics.com/index.php?route=product/product&product_id=92
[23:23] <russss> I have a HP GPS-disciplined refclock which I got for free. it still needs a bit more work
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[23:23] <russss> but it has a 10MHz output which is neat
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[23:24] <russss> not HP, Lucent. https://wiki.london.hackspace.org.uk/view/Project:Time_Source
[23:24] <Laurenceb_> nice
[23:25] <russss> my other project is to try and build a cheap survey-grade GPS receiver for mapping the next EMF site :P
[23:26] <Laurenceb_> radioshack.dhcp.lan.london.hackspace.org.uk ping statistics ---
[23:26] <Laurenceb_> 14 packets transmitted, 0 received, 100% packet loss
[23:26] <Laurenceb_> booo
[23:26] <russss> I think that particular incarnation is no longer working, but I'd like to get back into it
[23:27] <russss> this thing is ~£30 and gives you raw GPS phase data over serial, which RTKlib can process http://www.nvs-gnss.com/products/receivers/item/2-nv08c-csm.html
[23:28] <russss> actually the power supply I was using for that Lucent thing literally exploded, blew three circuit breakers and filled the room with magic smoke, and I think ended up shorting mains voltage to the output. I wasn't close to overloading it.
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[00:00] --- Tue Jan 3 2017