highaltitude.log.20081029

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[01:06] <Laurenceb> yo
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[11:38] <rjharrison> Oohh. The lovely radiometrix modules have arrived on 434.075
[12:15] <EI5GTB> i cant hear them
[12:15] <EI5GTB> :P
[12:15] <EI5GTB> if i tune my rig to that will i receive some?
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[13:32] <rjharrison> You will soon'ish
[13:32] <rjharrison> jcoxon is hoping to get up in the air on Sunday
[13:51] <EI5GTB> cool
[13:51] <EI5GTB> wonder could i pick it up from here..
[13:54] <EI5GTB> right, time to move stuff around in the shack
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[14:15] <rjharrison> hi edmoore
[14:15] <rjharrison> Lecture gap?
[14:16] <rjharrison> My 434.075's arrived todday
[14:16] <edmoore> finished lectures for the day
[14:16] <edmoore> about to head down to fergus's room to layout the new badger board
[14:16] <rjharrison> BTW did you see this http://www.robertharrison.org/files/radio/IMG_0435.JPG
[14:16] <rjharrison> Ohh it's sednesday
[14:16] <rjharrison> wednesday
[14:17] <rjharrison> Didn't one of you agree to keep it free
[14:18] <edmoore> keep what free?
[14:19] <rjharrison> Wed. eve for badger
[14:20] <edmoore> i think it takes at least two to a'gree'
[14:20] <edmoore> 'agree'*
[14:20] <edmoore> but pedantry asside, yes
[14:20] <rjharrison> nice word
[14:20] <gordonjcp> lol
[14:20] <edmoore> but I have a morse lesson later and he has a supervision in a bit
[14:20] <gordonjcp> a'gree'
[14:20] <gordonjcp> "hmm" I thought, "why are they forcing it to ASCII?"
[14:21] Action: gordonjcp needs to get off this python project
[14:23] Action: rjharrison lol's
[14:28] <edmoore> back
[14:28] <edmoore> ok, pcb after histroy of maths
[14:28] <edmoore> we keep putting this off
[14:28] <edmoore> sigh
[14:30] <gordonjcp> http://www.gjcp.net/~gordonjcp/panorama2.jpg
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[14:45] <jcoxon> afternoon all
[14:47] <gordonjcp> jcoxon: hello
[14:47] <jcoxon> hey gordonjcp
[14:48] <edmoore> jcoxon: yo
[14:49] <edmoore> gordonjcp: too much :p
[14:49] <jcoxon> edmoore: thanks for forwarding the email
[14:49] <edmoore> np
[14:51] <jcoxon> its hard not to watch the weather :-)
[14:51] <jcoxon> still too early
[14:51] <edmoore> jcoxon: how many does it take to tango?
[14:51] <edmoore> think icecream
[14:54] <jcoxon> ?
[14:58] <gordonjcp> edmoore: :-p
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[15:53] <rjharrison> gordonjcp: I like it surreal
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[17:19] <edmoore> s'up yaw
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[18:24] <Laurenceb> hi rjharrison
[18:24] <Laurenceb> is Icarus I yours?
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[18:26] <Laurenceb> hi edmoore
[18:28] <edmoore> hi Laurenceb
[18:29] <edmoore> what's new?
[18:31] <Laurenceb> well I'm just off to check my pidge
[18:31] <Laurenceb> hopefully there will be a heat sealer arrived
[18:31] <edmoore> nice
[18:32] <Laurenceb> I've added I2C eeprom support to the mini rogallo code
[18:32] <Laurenceb> it should be ready for launch in a few weeks
[18:35] <rjharrison> Laurenceb Yep
[18:37] <rjharrison> Laurenceb Where have you been reading about Icarus
[18:37] <Hiena> ' evening!
[18:37] <Laurenceb> on the wiki
[18:38] <rjharrison> ahh I have a link to the pics if you missed them
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[18:41] <Laurenceb> brb
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[20:00] <rjharrison> Evening RocketBoy
[20:00] <rjharrison> Thanks for your email the other day I'm now the proud owner of 3 NTX2 434.075
[20:06] <RocketBoy> yeah - thats probably the way to go for the short to mid term IMO
[20:07] <Laurenceb> hi rocketboy
[20:08] <rjharrison> Now to get rtty working. Is the best way to use a voltage divider or do you have someother way?
[20:11] <RocketBoy> yeah the simplest way (it seems from the NOVA camp) is to use very slow (50baud) RTTY - with a voltage divider to get the small shift
[20:12] <RocketBoy> you can get faster speeds and or more distance by shaping the pulses - but a simple voltage divider seems to work OK so I'm told
[20:12] <RocketBoy> hi LaurenceB
[20:19] <Laurenceb> Rocketboy: did you ever get anywher ewith the thermopile unit?
[20:22] <RocketBoy> no - do you want me to send it back
[20:23] <Laurenceb> well I'm not going to be able to work on it quite yet
[20:24] <rjharrison> Humm how does one shape a pulse.
[20:24] <RocketBoy> well i might have more time in January
[20:25] <RocketBoy> as my contract ends dec.
[20:26] <RocketBoy> pulse shaping - DAC (D2A) - PWM or analoge circuit (diodes/capacitors/resistors etc)
[20:30] <RocketBoy> I used a 4 bit DAC on a PIC chip - as have the NOVA team in the past
[20:30] <rjharrison> Humm so it must be quite easy to use a dac chip with my avr to give nicely shaped rtty pulses to boost my baud rate. I was hoping for at least something like 300
[20:31] <rjharrison> I guess I can pic up a dac from farnell and connect it to the avr ATMEGA8 its a very basic avr chip
[20:31] <RocketBoy> yeah that what we typically achieve with pulse shaping 300baud out to 300Km (or more)
[20:31] <rjharrison> Woof, That will do me
[20:32] <rjharrison> I don't know much about dac's but if a I get a 4 bit one that's going to be enough for rtty purposes I guess
[20:32] <rjharrison> RocketBoy: I may see you at the w/e weather depending
[20:33] <RocketBoy> thats what i have used - with good results - the more bits the better
[20:33] <rjharrison> Ahh interesting. I guess dac chips are quite cheep ie less than 20 quid
[20:33] <RocketBoy> on the downside need to consider extra power (if micro power is your thing)
[20:35] <RocketBoy> its no good having a 20mA, 10mW transmitter if you waste 20mA on the DAC functionality (IMO)
[20:36] <RocketBoy> just a consideration
[20:37] <Laurenceb> RocketBoy: how does pulse shaping help?
[20:37] <RocketBoy> its all to do with bandwidth and sharp edges
[20:38] <Laurenceb> sure
[20:38] <Laurenceb> but we want range?
[20:38] <Laurenceb> if e.g. you have high and low I and Q
[20:38] <RocketBoy> a very rough rule of tumb for FM is bandwidth = 2 x (fd + fm)
[20:38] <Laurenceb> then integrate over a period of 1/300 seconds
[20:39] <RocketBoy> whene fd is the frequency shift from 0 to 1
[20:39] <RocketBoy> and fm is the frequncy of the modulated signals (i.e. the edge)
[20:39] <Laurenceb> taking a descriminator function of sqrt(I_H^2+Q_H^2)-sqrt(I_L^2+Q_L^2)
[20:39] <Laurenceb> where L is lower frequency and H is the higher
[20:40] <Laurenceb> then if there is no pulse shaping you get the strongest signal out
[20:40] <RocketBoy> so with sharp edges the energy is dispersed over a large bandwidth
[20:40] <Laurenceb> sure
[20:40] <Laurenceb> but with a local oscillator and I Q integration bins it doesnt matter
[20:41] <Laurenceb> with a convensional analogue discriminator it might be different
[20:41] <Laurenceb> but we're using a digital one
[20:41] <RocketBoy> lauurence - im still trying to discribe the so - listen
[20:41] <Laurenceb> ok :P
[20:42] <RocketBoy> so with a 0 to 1 transition the energy will be dispersed over the frequency represented by 0
[20:42] <RocketBoy> and likewise the other way
[20:43] <RocketBoy> this confuses the decoder - its called inter symbol interfereance ISI IIRC
[20:44] <RocketBoy> interference reduces the immunity to noise etc.
[20:45] <rjharrison> RocketBoy: Is this why my cw is a little chirpy?
[20:45] <RocketBoy> so with nicly shaped pulses the spread is localised around the symbol level (0 or 1)
[20:45] <rjharrison> Not my words but those of some one who may know more than me
[20:45] <RocketBoy> thats as I understand it
[20:46] <rjharrison> RocketBoy: Sounds very indepth explaination there is a bit on wikipedia
[20:46] <RocketBoy> not really chirpy - thats caused by a slight drift due to the transmitter ferquency stabilizing
[20:46] <RocketBoy> but what you do get is "clicks"
[20:47] <rjharrison> http://en.wikipedia.org/wiki/Pulse_shaping
[20:47] <RocketBoy> which mean that your causing interference
[20:47] <RocketBoy> and dispersing your power to wher you don't want it
[20:48] <rjharrison> How would I improve on that?
[20:48] <rjharrison> If we do get together on sunday would you mind if I draged icarus down of you to give it a quick eye ball
[20:48] <rjharrison> of = for
[20:52] <Laurenceb> RocketBoy: but as we have a very large bandwidth (~3KHz) cant we afford to use a non pulse shaped signal?
[20:52] <Laurenceb> (very large compared wirth the baud rate)
[20:52] <RocketBoy> with CW if you are keying the transmitter on and off - the better thing would be to try and shape the envelope of the transmitter signal (amptitude modulate it)
[20:53] <RocketBoy> I dont know if the NTX2 will let you do this - you could try the /EN line
[20:53] <RocketBoy> and see if you can put an analoge signal in to control the output level
[20:54] <RocketBoy> by shaping the on to off you should remove the clicks
[20:56] <RocketBoy> laurence - your right its all about how much time and effort you want to put into it vs the benift
[20:57] <RocketBoy> on the limit even though the reciver channel is 3KHz - truetty has audio filters that reduce this to a few hundred hZ
[20:58] <RocketBoy> if you are spreading the signal over 3KHz - but only listening to 600 Hz you are wasting 4/5th of your signal
[20:59] <RocketBoy> form the formula I gace you can see that a 200hz shift 300bps signal will fit in 700Hz
[20:59] <RocketBoy> gave
[21:00] <RocketBoy> I'm sure you remember the specturm on the true tty display
[21:00] <RocketBoy> as being much smaller than 3KHz
[21:01] <RocketBoy> what I think is true is that if the baudrate is slow the transitions cause interfereence for only a small % of the overall time
[21:02] <RocketBoy> which is why at 50 baud its much less of an issue
[21:03] <Laurenceb> guess it depends how truetty works
[21:03] <RocketBoy> (for the same bandwidth as 300 baud)
[21:04] <Laurenceb> the method I described with two (digital) local oscillator sources
[21:04] <Laurenceb> would work best with unshaped
[21:05] <Laurenceb> can you multiply by a local shaped signal?
[21:05] <RocketBoy> I think you will find that the laws of physics don't change no matter how you generate the signals
[21:05] <rjharrison> Humm this rtty stuff isn't quite as simple as cw. I'm going to get this working though.
[21:06] <rjharrison> I really should shape to make it worth the jump from cw to rtty
[21:06] <rjharrison> I'll investigate an 8+ bit dac and take it from there
[21:07] <RocketBoy> multiply the signal with a local shaped pulse - yes thats ampitude modulation (envelope modulation)
[21:07] <Laurenceb> I mean at the reciever end
[21:07] <rjharrison> Any well known DIP DAC's out there or am I on my own for this
[21:07] <RocketBoy> but you cant do that with a licence exempt module - beuse you would be modufying the output before it gets to the antenna
[21:07] <Laurenceb> use pwm
[21:08] <rjharrison> I think the avrs come with PWM on them
[21:08] <rjharrison> Is that an option worth following guys?
[21:08] <Laurenceb> yep
[21:08] <Laurenceb> thats how I do it
[21:09] <rjharrison> 50 baud or 300 baud?
[21:09] <RocketBoy> what transmit the signal iunshaped (spreading the bandwidth where its not wanted) and then recive it and shape it?
[21:09] <Laurenceb> RocketBoy: I meant for recieving shaped
[21:09] <RocketBoy> I'd suggest you go with unshaped 50 baud to begin with
[21:10] <RocketBoy> sorry I don't follow laurenceb
[21:10] <RocketBoy> can you draw it
[21:10] <Laurenceb> rjharrison: http://wiki.ukhas.org.uk/code:radio
[21:10] <Laurenceb> RocketBoy: basically I'm asking whats the best way to make a software discriminator to recieve shaped
[21:12] <RocketBoy> Its beyond my experiance - it strongly depends on the modulation technique I suspect
[21:12] <RocketBoy> so if its just FSK then sampling and FFTs for selcting the frequencies I would expect
[21:13] <Laurenceb> yeah
[21:13] <Laurenceb> but that works best for unshaped
[21:13] <Laurenceb> as you can confine everything to one frequency bin
[21:13] <Laurenceb> rjharrison: thats for the 168
[21:14] <RocketBoy> but for unshaped your not - there are 2 frequency bins - but they are going to be disturbed each time there is a transition
[21:16] <RocketBoy> so effectivly either the integration time is shortended (becuse you are ignoring the bins around the time of the transition)
[21:16] <RocketBoy> or you accept a lower noise threshold
[21:17] <RocketBoy> becuse noise from other sources + transition noise will false trigger
[21:18] <Laurenceb> just off the top of my head I was thinking of multiplying by a local shaped source
[21:18] <Laurenceb> in the same way an fft can bethought of as multiplying by an unshaped signal
[21:19] <RocketBoy> thats not the way I think of FFTs
[21:19] <RocketBoy> (I may be wrong)
[21:20] <Laurenceb> well its multiplying by a sin and cosine wave
[21:20] <RocketBoy> I just look at FFTs a time domain to frequency domain conversion
[21:20] <Laurenceb> so if you set one up to act as a discriminator, you are multiplying by local signal replicas
[21:21] <RocketBoy> yest the butterflys are made up of complex number multiplys of sin and cos weights
[21:22] <RocketBoy> yeah - its sounds like just another way of thinking about it
[21:23] <RocketBoy> the way I would have used an FFT - would be to FFT the input sample - and then examine each of the frequency buckets in the FFT output
[21:23] <Laurenceb> rjharrison: I havent actually tried that code with a reciever, as I havent got one, but if you want to try it and have any issues I'd be happy to help out
[21:24] <RocketBoy> and made the 0/1 decision based on where the power was distributed above below a frequency 1/2 way between the two
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[21:30] <jcoxon> evening all
[21:57] <jcoxon> right, new radio is installed
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[22:06] <Laurenceb> when are you launching?
[22:08] <jcoxon> prob sunday
[22:19] <RocketBoy> sunday seemed best when I looked lunchtime - but u know how it goes
[22:21] <jcoxon> yeah sunday looks good
[22:21] <jcoxon> but i'll keep an eye
[22:23] <jcoxon> RocketBoy, i've shifted to 434.075 ( though it seems to broadcast at 434.073)
[22:23] <jcoxon> and have but some gaps in the transmission
[22:23] <RocketBoy> spot on - the more gaps the better
[22:23] <jcoxon> i'm doing a burst of 5 strings then sleep for 5 secs
[22:24] <jcoxon> with the EN pin off
[22:24] <RocketBoy> I think there is a duty cycle spec for LE somewhere
[22:24] <jcoxon> that way it gives us time to tune up and get useable data
[22:29] <jcoxon> nice free module from radiometrix :-D
[22:32] Action: RocketBoy wishes he could get free modules form radiometrix
[22:32] <Laurenceb> free?
[22:32] <Laurenceb> how do you pull this off?
[22:32] <jcoxon> i have to write an write up for them
[22:32] <jcoxon> i just emailed enquiring about buying a module and put a link in my signature to pegasushab
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[22:33] <Laurenceb> oh so they can write an application note?
[22:34] <Laurenceb> hi ed
[22:34] <jcoxon> i think its more for use in articles in electronic magazines etc
[22:34] <Laurenceb> ok
[22:35] <Laurenceb> they make you work for your modules :P
[22:35] <Laurenceb> the NTX2 has become a new currency
[22:36] <Laurenceb> edmoore: I've been experimenting with plastic welding
[22:36] <Laurenceb> this bag sealer doesnt really work with thin polythene
[22:36] <edmoore> cool
[22:36] <Laurenceb> it seems polythene sticks to teflon
[22:36] <Laurenceb> when its hot
[22:37] <Laurenceb> thick stuff >~30um is ok
[22:37] <Laurenceb> but thin stuff tears
[22:37] <edmoore> hrm
[22:37] <Laurenceb> have you seen this?
[22:37] <edmoore> you do have to let it cool...
[22:38] <edmoore> so if we welded a strip then tried to pull it up, it would tear
[22:38] <edmoore> but it un-sticks once it's cooled down
[22:38] <Laurenceb> yep thats what I see
[22:38] <Laurenceb> unfortunately these bag sealers have to be pulled along the seam
[22:38] <Laurenceb> looks like its a no go
[22:40] <RocketBoy> ha - the offcom spec shows no duty cycle restriction for 434.040 - 434.79MHz
[22:41] <edmoore> suits us!
[22:41] <Laurenceb> edmoore: your using a welding machine that doesnt slide the polythene over the element?
[22:42] <edmoore> correct
[22:42] <RocketBoy> so are ptfe rollers out then (surprise)
[22:43] <RocketBoy> ?
[22:43] <Laurenceb> not necessarily
[22:43] <edmoore> we use rolling elements
[22:43] <Laurenceb> but you need a larger heating time?
[22:43] <Laurenceb> *longer
[22:43] <Laurenceb> i.e. heated teflon belts?
[22:44] <Laurenceb> rollers have a very small contact area
[22:44] <RocketBoy> difficult to get pressure with a belt?
[22:44] <edmoore> nope
[22:44] <edmoore> just rollers
[22:45] <Laurenceb> interesting
[22:45] <Laurenceb> intuatively I would have thought there would be problems getting the heat to diffuse into the wled area fast enough
[22:46] <Laurenceb> whats the roller diameter?
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[22:57] <RocketBoy> Ohhhhh Woww - Ofcom just changed the spec on licence exempt equipment - the new document (dated September 2008) allows for a load more frequences to be used for airborne operation - I'm glad I decided to read it again
[22:57] <jcoxon> oooooo
[23:00] <RocketBoy> including 500mw on 869.40- 869.65 MHz < 10% duty cycle
[23:00] <Laurenceb> omg
[23:00] <jcoxon> wow
[23:00] <Laurenceb> licence exempt?
[23:00] <RocketBoy> yep
[23:00] Action: Laurenceb starts work on HDTV downlink
[23:00] <Laurenceb> where is this?
[23:01] <RocketBoy> 500mW more than makes up for the higher free space path loss on 869MHz over 434MHz
[23:02] <RocketBoy> Document IR2030 on the offcom site
[23:02] <natrium42> whoa, congrats guys
[23:02] <Laurenceb> ok
[23:02] <RocketBoy> I was only looking at it a couple of months ago and i'm sure it wasn't there then
[23:04] <RocketBoy> ha the radiometrix TX3H is the new currency
[23:05] <Laurenceb> hmm thing is to take advantage of this we need a good recieve system
[23:05] <RocketBoy> 500mw on 869.5MHz
[23:05] <jcoxon> http://www.atysco.eu/en/products/show/549
[23:05] <Laurenceb> I guess this is where pulse shaping comes into its own
[23:05] <Laurenceb> as we can then get ~3Kbps
[23:07] <RocketBoy> I actually have one - which I bought for somthing else
[23:09] <Laurenceb> jcoxon: whats the range?
[23:11] <RocketBoy> Its specked at about 1Km I think - I got it for the EARS radio launch controller
[23:12] <RocketBoy> it seems to be the 500mw / 869MHz equivelnet of the NTX2
[23:12] <RocketBoy> need a good 869MHz Receiver though
[23:15] <RocketBoy> it certainly opens up higher data rates/range
[23:15] <jcoxon> :-)
[23:15] <RocketBoy> with 500Mw
[23:15] <RocketBoy> we might just use VHF packet on FM
[23:15] <RocketBoy> sooo much simpler
[23:16] <jcoxon> where is the fun though :-D
[23:16] <RocketBoy> and no interfereance with hams!
[23:17] <jcoxon> RocketBoy, does the packet code cover this?
[23:18] <Laurenceb> hmm that atysco thingy is specced at 4Km
[23:19] edmoore (n=edmoore@pomegranate.chu.cam.ac.uk) joined #highaltitude.
[23:20] <RocketBoy> jcoxon: yes - its one of the options
[23:20] <jcoxon> edmoore,
[23:20] <jcoxon> 869 at 500mW
[23:20] <jcoxon> its allowed...
[23:20] <Laurenceb> -105 dBm
[23:20] <Laurenceb> (@ 4.8 Kbps)
[23:20] <Laurenceb> according to the datasheet for that thingy
[23:20] <Laurenceb> so what the range?
[23:21] <Laurenceb> its a few hundered Km theoretically? with a 500mw tx?
[23:22] <RocketBoy> edmoore: ofcom have just changed the licence exempt spec to allow more frequencies to be used airbore
[23:22] Action: jcoxon is suprised edmoore isn't screaming
[23:22] <jcoxon> perhaps he is just not virtually
[23:23] <edmoore> hang on hang on hang on
[23:23] <edmoore> start again
[23:23] <RocketBoy> so 500mw is about 17db up on 10mw
[23:23] <edmoore> i didb't clock all that
[23:23] <edmoore> wait wait wait
[23:23] <edmoore> from the top
[23:23] <jcoxon> new licence regulations - we are allowed to use 869 at 500mW
[23:23] <RocketBoy> but free space path loss on 868MHz is 6db up on 434MHz (me thinks)
[23:23] <edmoore> :o
[23:24] Last message repeated 2 time(s).
[23:24] <edmoore> :o:o:o
[23:24] <edmoore> ok
[23:24] <edmoore> stay calm
[23:24] <edmoore> fuck
[23:24] <edmoore> sorry that wasn't calm
[23:24] <edmoore> ok ok, we need to find a new transmitter to become the standard
[23:24] <edmoore> or test a bunch
[23:24] <Laurenceb> lol
[23:25] <RocketBoy> but 868MHz antenna will be up 3db on a 434MHz antenna of the same length
[23:25] <jcoxon> http://www.radiometrix.co.uk/products/tx3h.htm
[23:25] <RocketBoy> so the net improvement is say 14db
[23:26] <edmoore> need to find a decent ground rig too
[23:28] <Laurenceb> http://www.atysco.eu/en/products/show/549
[23:28] <Laurenceb> ^ that? for both ends?
[23:31] <edmoore> ok, need to run for about 20 mins
[23:31] <edmoore> poo
[23:31] <RocketBoy> which means about 20x the data rate for the same S/N me thinks 6Kbps at 300Km
[23:31] Nick change: edmoore -> edmoore|away
[23:32] <Laurenceb> with two of those modules I think you could have a two way 4.8Kbps link
[23:32] <RocketBoy> I think we determined the FM range threshold was about 30Km
[23:33] <RocketBoy> (434MHz 10mW) so for 14db up thats about 120Km for 500mW on 868MHz
[23:43] <Laurenceb> for that module from atysco?
[23:44] <RocketBoy> nope for standard AFSK packet radio
[23:44] <Laurenceb> I find a range of approx 300Km using the -105dbm sensitivity on the datasheet
[23:45] <Laurenceb> so you could have a 4.8Kbps two way datalink :P
[23:45] <Laurenceb> a yagi is approx 12dbi ?
[23:46] <RocketBoy> yes sounds about right
[23:46] <gordonjcp> depends on the yagi
[23:47] <RocketBoy> possibly a couple of db adrift
[23:48] <Laurenceb> that would be insane
[23:49] <Laurenceb> 4.8Kbps XD
[23:49] <Laurenceb> and an uplink
[23:50] <RocketBoy> don't forget no antennas with gain in the transmit line
[23:50] <Laurenceb> sure
[23:51] <Laurenceb> hmm pity about the current consumption - 600ma @ 3.3v
[23:51] <SpeedEvil> s
[23:51] <SpeedEvil> oops
[23:51] <RocketBoy> yeah well that the downside to more power
[23:53] <RocketBoy> so thats 2W in for 0.5w out - 25% efficncy (average or worse than average for that sort of frequency)
[23:53] <edmoore|away> something that would do a 1.2kbps uplink would be supertastic
[23:53] <Laurenceb> they dont stock it on the breakout board
[23:53] <Laurenceb> which is a pity
[23:53] <edmoore|away> sorry, 1.2kbps downlink and a passable uplink
[23:53] <Laurenceb> edoore: that does 4.8Kbps uplink
[23:54] <Laurenceb> and downlink
[23:54] Nick change: edmoore|away -> edmoore
[23:54] <Laurenceb> http://www.atysco.eu/en/products/show/549
[23:54] <RocketBoy> night guys
[23:54] RocketBoy (n=Steve@217.47.75.27) left irc: "Leaving"
[23:55] <edmoore> what the module does and what the whole system can do probably differ
[23:56] <Laurenceb> well I've just chucked in some numbers
[23:56] <Laurenceb> and it looks like range should be ~300Km at 4.8kbps
[23:57] <Laurenceb> with an lna/huge yagi you could get better
[23:59] <jcoxon> right i'm off
[23:59] <jcoxon> night all
[23:59] jcoxon (n=jcoxon@host81-152-142-209.range81-152.btcentralplus.com) left irc: "Leaving"
[00:00] --- Thu Oct 30 2008