After researching near space balloon projects and launching two of my own I've found that the major hurdle is in communication with the balloon payload. Many near space ballooners are using HAM radio equipment to track their balloons through triangulation or APRS data transmissions. That's all well and good if you have a HAM license and the experience to know what equipment and frequencies to use. The non-HAM ballooners are using cellphones or cellular modules to send SMS messages for tracking the flight. Cellular modules work pretty well up to 40k feet altitudes with good external antennas, but above that altitude there will be no communication from the payload. It's a bit nerve racking not knowing what's going on with the payload for more than half of the flight. Cellular coverage isn't always available in the best launch locations in the U.S.
I discovered that the communications challenge is very simple with the right hardware. The XTend900 radio from Digi (http://www.sparkfun.com/products/9411 ) and a high gain patch antenna (http://www.l-com.com/item.aspx?id=20447 ) can keep you in communication with the payload for the entire flight and can even provide enough bandwidth to transmit small pictures. This instructable will focus on the minimum set of hardware to get you into near space, capture those spectacular photos, and track your payload to recovery.
For information on my last near space flight, Night Sky, visit barney.gonzaga.edu/~lwardens
I discovered that the communications challenge is very simple with the right hardware. The XTend900 radio from Digi (http://www.sparkfun.com/products/9411 ) and a high gain patch antenna (http://www.l-com.com/item.aspx?id=20447 ) can keep you in communication with the payload for the entire flight and can even provide enough bandwidth to transmit small pictures. This instructable will focus on the minimum set of hardware to get you into near space, capture those spectacular photos, and track your payload to recovery.
For information on my last near space flight, Night Sky, visit barney.gonzaga.edu/~lwardens
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Signing UpStep 1: GPS Tracking
Your near space project will be a disaster if you don't know where the payload lands. The easiest way to track the flight is with a GPS receiver. Not all GPS receivers are equal, though. Some receivers can track 30+ satellites at a time, report the position 10 times a second, and output the raw data from the satellites. We aren't making an unmanned aerial drone, and even if we were there are only 12 GPS satellites in view of a hemisphere at one time...don't get suckered into buying an expensive GPS because the numbers are impressive. The one important thing is to get a receiver that can operate above 60k feet altitudes. Many receivers stop working above that altitude due to international export restrictions and what not.
For my projects I have used the GS407 receiver (http://www.sparkfun.com/products/9436). This is a small receiver with a helical antenna that gets great reception. The U-Blox chipset can interface with the U-Center software to set all the device parameters and update the satellite almanac for faster startup times (http://www.u-blox.com/en/evaluation-tools-a-software/u-center/u-center.html). Using U-Center you can also update the "dynamic platform Model" which allows this receiver to operate above 60k feet. You must set the dynamic platform model to "Airborne < 2g" or higher to operate above 60k feet. I'll discuss how to change that setting after we have the GPS and radios connected.
For now all we have to do to the GS407 is solder 4 wires on. In the picture you can see that the serial communication comes out of pins 3 & 4 of the U-Blox module. Pin 6 is VCC or power and pin 14 is ground, which you also need as a reference for the serial bus. Solder a wire to each of these pins, you should be able to do it without a microscope using 30 gauge solid core wire. If you use 4 different color wires you'll make your life easier, too. If you feel nervous about soldering these wires you can buy a breakout board (http://www.sparkfun.com/products/10496) for the GS407 that will provide slightly larger holes to solder to, but you're still going to have to solder.
For my projects I have used the GS407 receiver (http://www.sparkfun.com/products/9436). This is a small receiver with a helical antenna that gets great reception. The U-Blox chipset can interface with the U-Center software to set all the device parameters and update the satellite almanac for faster startup times (http://www.u-blox.com/en/evaluation-tools-a-software/u-center/u-center.html). Using U-Center you can also update the "dynamic platform Model" which allows this receiver to operate above 60k feet. You must set the dynamic platform model to "Airborne < 2g" or higher to operate above 60k feet. I'll discuss how to change that setting after we have the GPS and radios connected.
For now all we have to do to the GS407 is solder 4 wires on. In the picture you can see that the serial communication comes out of pins 3 & 4 of the U-Blox module. Pin 6 is VCC or power and pin 14 is ground, which you also need as a reference for the serial bus. Solder a wire to each of these pins, you should be able to do it without a microscope using 30 gauge solid core wire. If you use 4 different color wires you'll make your life easier, too. If you feel nervous about soldering these wires you can buy a breakout board (http://www.sparkfun.com/products/10496) for the GS407 that will provide slightly larger holes to solder to, but you're still going to have to solder.
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Payload
- 1 GS407
- 1 breakout board w/ resistor
- 1 battery
- 1 antenna
Ground
- 1 XTend 900 radio module
- 1 uUSB-MB5
- 1 breakout board w/ resistor
However, the numbers don't match up and I can't seem to find where/how the second XTend 900 radio module connects. Any mention of the XTend 900 radio module only refer to it being connected to the PC. Could you please clarify?
If I follow the numbers you give in step 9, would that would suggest that the second antenna is on the ground connected to the XTend 900 radio and the second XTend 900 radio is in the payload, connected to the antenna (by the way, does that connection need an adapter?) and the breakout board. Since the GS407 also needs to be connected to a breakout board, do they share one?
Thank you
Balloon payload:
-GS407->XTend breakout->XTend radio->antenna
Ground Station:
-Antenna->XTend radio->XTend breakout->uUSB-MB5->Computer
If you live on a small island, it tends to fly into the sea :P Any suggestions will be appreciated!
You can increase the rate of NMEA messages from the GPS reciever to 5 per second on the GS407. Your best bet, if you must launch from an island, is to make your payload waterproof and buoyant. Do very careful flight plan predictions, fill your balloon precisely to get the rate of ascent right, pick your parachute for proper rate of descent, and get a fast boat so you can be at the landing zone before the payload lands. If you make the payload so it floats with the antenna facing up, you should be able to receive the signal well over a mile away from the payload. If the antenna is under water...you'll never hear from it again.
Might be cool to make the payload an autonomous boat that drives itself back to the closest shoreline.
With the new GS407, the setting is the same <2G airborne, but it is no longer under the NAV section. It's now in the NAV2 or NAV5 depending on the firmware version you have. You'll still see the NAV, NAV2, and NAV5 sections with any firmware version, so the easiest thing to do is set it in all three. Then it's done and you didn't have to worry about reading out the firmware version.
I am an AP Physics teacher. I want my students to do this as a class project. I will get all the materials then they will follow your instructions. Do you think 17-18 year old students would be able to complete this project?
Thanks in advance for your advice.
** I'm just running simulations to get used to the program for now as I research and build my payload etc. I do seem to be able to run current simulations if I leave the date as it is and launch tiem by default.
Jason
Jason
http://www.instructables.com/id/My-Space-Balloon-Project-Stratohab-Success-High/
It would be great if you help me build the tracker. I am based in Australia and would love your input.
Up to it?
I also don't think I've ever had a problem looking at the prediction in Google Map.
However, I'm thinking about making a rockoon in the near future. The balloon would lift a rocket to altitude and then the rocket would shoot right through the balloon. It would be crazy awesome to see a giant hydrogen explosion as the rocket goes through the balloon!
I've done five high altitude balloon launches (www.thetalon.smugmug.com/misc/space). If you use it safely, there's nothing wrong with using hydrogen. It's cheaper (a cylinder rents for $60. The same size helium is over $100) and it has more lift by volume. We are looking at doing a flight to break the altitude record in June. If we try it, we will be using hydrogen.
I think you might want to take a second look at the ham radio transmitters too. I'm not an electronics guy, just someone who wanted to photograph space. But I was able to figure it out. :)
We've done five launches and gotten four back. We use a Byonics transmitter attached to a Garmin 18x GPS and a simple antenna. Plus a SPOT satellite messenger. Plus the loudest piezo buzzer I could find. :)
The photos are online at www.thetalon.smugmug.com/misc/space.
Perfect testbed for trying out some "lifter" configurations, with the electrodes painted/glued on the balloon's surface.
Have a look at supercapacitors instead of Lipo batteries (http://www.maxwell.com/products/ultracapacitors/product.aspx?PID=K2-SERIES)
Well now I have 2 more questions for you. If you know, what is the FAA limit for unmanned flight.
And 2, How high up would a drone have to be to transmit a satellite signal over, lets say, 10-20 miles? I suppose I could figure that out with some math, but it would be easier to find out if you knew.
As for transmitting a satellite signal, I'm assuming you mean your UAV acts like a satellite... It depends a lot on the topography of the ground beneath you. I was able to get a 20 mile radio link out of my last balloon with just a few thousand feet altitude. The ground there was very flat and there were no trees, though. In a mountainous area with trees you will need to get line-of-sight to the bottom of each valley and that might mean tens of thousands of feet.
Besides it's a pain to hack the free version google earth into working with gps.