High altitude balloon payload, from Sable-3 discussion |
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High altitude balloon payload, from Sable-3 discussion |
 Oct 20 2007, 03:16 AM
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#136
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 Merciless Robot  Group: Admin Posts: 8783 Joined: 8-December 05 From: Los Angeles Member No.: 602  |
It should. Most standard GPS devices output data in the NMEA 0183 format, and the $GPGAA string includes altitude data, IIRC. However, this isn't referenced to terrain or local elevation but rather to the WGS84 spheroid model of the Earth, so uncertainty of a few meters is a given (although I've also seen GPSs freak out & give whacko elevation data pretty often during flight...)
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Oct 20 2007, 06:30 AM
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#137
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 Senior Member Group: Admin Posts: 4763 Joined: 15-March 05 From: Glendale, AZ Member No.: 197 |
QUOTE (nprev @ Oct 19 2007, 07:16 PM)  However, this isn't referenced to terrain or local elevation but rather to the WGS84 spheroid model of the Earth, so uncertainty of a few meters is a given Well the way to calibrate for that is to take a "zero" reading at ground level prior to launch. -------------------- If Occam had heard my theory, things would be very different now.
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Oct 20 2007, 07:49 AM
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#138
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
QUOTE (ElkGroveDan @ Oct 20 2007, 02:56 AM) Does the data from the GPS device include ALTITUDE? Pay attention Dan  http://www.unmannedspaceflight.com/index.p...st&p=101948 Doug |
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Oct 20 2007, 01:08 PM
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#139
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Merciless Robot Group: Admin Posts: 8783 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
It's too bad that there's not a compact differential GPS (DGPS) receiver available for greater precision...those things can give you 10cm X-Y positional accuracy wrt the surface, plus largely obviate the altitude freak-outs I mentioned earlier. In the UK, correction signals are transmitted in the 300 KHz band, though, so would have to add a fairly hefty antenna to get any degree of reliable performance. DGPS is mostly intended for maritime use, so most of the available (and less expensive) equipment is too heavy for this particular application.
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Oct 20 2007, 01:26 PM
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#140
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 Junior Member Group: Members Posts: 53 Joined: 10-September 05 Member No.: 492 |
I have no specific knowledge of lightweight DGPS kit but the antenna for 300kHz shouldn't be a problem. For transmission at that frequency I'd agree than you'd need something pretty substantial but for reception an active antenna (such as http://www.radiopassioni.it/pdf/pa0rdt-Mini-Whip.PDF ) would work well with a length of <100mm and pretty low weight.
Watching this thread with great interest. Brilliant stuff! Rob |
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Oct 20 2007, 02:02 PM
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#141
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Merciless Robot Group: Admin Posts: 8783 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
Ah! Did not consider active antennas, just passive. Haven't messed with DGPS since 1998, when I connected a Magnavox MX50 DGPS receiver to one of the automatic direction finder antennas of a C-141 (passive all the way, of course.) Seems the state of the art has improved a bit over nearly ten years (duh...)
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Oct 20 2007, 03:20 PM
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#142
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Senior Member Group: Admin Posts: 4763 Joined: 15-March 05 From: Glendale, AZ Member No.: 197 |
QUOTE (djellison @ Oct 19 2007, 11:49 PM) Pay attention Dan I was distracted in my zeal to include some kind of barometer. But I will raise the issue anyway. If the UMSF balloon goes anywhere near as high as the Sable-3 project we are emulating, then we will approach Martian atmospheric conditions, and that alone would be a cool fact to report on. And that raises another issue. Have we considered the effect of 10 millibars of pressure on each of the components? My first thought is the C-cells and the potential to burst if they are tightly sealed. -------------------- If Occam had heard my theory, things would be very different now.
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Oct 20 2007, 03:39 PM
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#143
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
If I can log temp, pres and GPS with a second Picaxe unit....I will. I want to do those temp/pres profiles
A small cheap pressure transducer is not something I've found yet though.Doug |
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Oct 20 2007, 03:45 PM
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#144
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Senior Member Group: Admin Posts: 4763 Joined: 15-March 05 From: Glendale, AZ Member No.: 197 |
QUOTE (djellison @ Oct 20 2007, 07:39 AM) A small cheap pressure transducer is not something I've found yet though. Look for the Motorola MPX100AP. -------------------- If Occam had heard my theory, things would be very different now.
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Oct 21 2007, 12:58 PM
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#145
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 Interplanetary Dumpster Diver Group: Admin Posts: 4404 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
QUOTE (ElkGroveDan @ Oct 20 2007, 03:45 PM) Look for the Motorola MPX100AP. I would be willing to provide this. -------------------- |
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Oct 23 2007, 07:08 PM
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#146
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 Director of Galilean Photography Group: Members Posts: 896 Joined: 15-July 04 From: Austin, TX Member No.: 93 |
Doug,
For a test flight, have you considered a kite? Given a large enough kite, a couple of KG of lift should be a cinch. Also, do you have a list of which components you are using? I would like to get a couple of those cameras for my own experimentation... In the spirit, we just purchased an Estes Astro-Cam digital camera rocket. Only have had two flights, one a near-tradgedy (flight tube damaged but serviceable) and the other a perfect, if slightly delayed, launch. Videos are at: http://video.google.com/videoplay?docid=45...44458&hl=en http://video.google.com/videoplay?docid=41...66003&hl=en -------------------- Space Enthusiast Richard Hendricks
-- "The engineers, as usual, made a tremendous fuss. Again as usual, they did the job in half the time they had dismissed as being absolutely impossible." --Rescue Party, Arthur C Clarke Mother Nature is the final inspector of all quality. |
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Oct 23 2007, 07:13 PM
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#147
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
http://www.aria.co.uk/SuperSpecials/Other+...productId=28103 is the camera - although to be honest, I may go with something a bit better or the actual flights - and use one of those for the monitoring camera
Doug |
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Oct 25 2007, 08:52 PM
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#148
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Director of Galilean Photography Group: Members Posts: 896 Joined: 15-July 04 From: Austin, TX Member No.: 93 |
Closest thing I could find is the 3.1 MP version of the catcam camera, a VistaQuest:
http://www.walmart.com/catalog/product.do?product_id=5614773 I might give it shot as a kite-cam for fun. During my copious free time, of course! -------------------- Space Enthusiast Richard Hendricks
-- "The engineers, as usual, made a tremendous fuss. Again as usual, they did the job in half the time they had dismissed as being absolutely impossible." --Rescue Party, Arthur C Clarke Mother Nature is the final inspector of all quality. |
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Oct 25 2007, 09:30 PM
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#149
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
The 1.3 MP VistaQuest is what the GMC is.
Doug |
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Oct 27 2007, 08:33 AM
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#150
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 Member Group: Members Posts: 562 Joined: 29-March 05 Member No.: 221 |
High ALtitude Object - HALO
30k balloon. This guy has a detiailed write up of how he did it with some awsome videos and photos of the results. 
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