Parallax Propeller Near-Space Balloon
leggs
Posts: 21
I am now an Electronic Engineering graduate. For my final year project I designed and launched a near-space balloon powered by the Parallax Propeller. I have attached my 50 page report and a slideshow for anyone who is interested, but I will also give a short description below:
The project was called SUNSET (Stellenbosch University Near-Space Engineering Testbed). It had the following capabilities:
Unfortunately, an hour into the flight, the payload stopped transmitting. It had traveled more than 50km and had reached 12km AGL altitude. The cause of the failure is still unknown, but I have a few theories. I am still waiting for a farmer to find my payload in his field! In the meantime I am working on SUNSET v2. This time images will be transmitted using SSTV. Using ROBOT8, images will be down-linked in 8 seconds, unlike the previous method, which required 2 minutes.
The report does not include information about the launch, but it is described, with some images, in the attached slideshow.
Thank you to the Parallax Propeller community for all your hard work and amazing bits of code. You are all given credit in my report if I made use of your code in some way. I have attached my code too. I am afraid it is not very neat or polished or organised, but it might be useful to someone attempting this in future.
The project was called SUNSET (Stellenbosch University Near-Space Engineering Testbed). It had the following capabilities:
- Powered by the Parallax Propeller clocked at 80MHz
- Primary communication link was a 300mW VHF Radiometrix module which transmitted APRS packets created and modulated by the Propeller.
- Backup coms link was a cheap ($22) GSM USB dongle which was hacked to be controllable over serial. It was supposed to send SMS messages upon landing.
- The Prop used a a small composite video camera to take low-res, BW images. Images were transmitted to the ground line by line during the flight also using APRS packets. Custom software I wrote in VB reconstructed and displayed the images on the ground station during the flight.
- Two thermistors measured inside and outside temperature.
- An onboard micro-SD card logged images, temperatures and GPS coordinates throughout the flight.
- Everything was powered by 6 AA Energizer Lithium batteries.
Unfortunately, an hour into the flight, the payload stopped transmitting. It had traveled more than 50km and had reached 12km AGL altitude. The cause of the failure is still unknown, but I have a few theories. I am still waiting for a farmer to find my payload in his field! In the meantime I am working on SUNSET v2. This time images will be transmitted using SSTV. Using ROBOT8, images will be down-linked in 8 seconds, unlike the previous method, which required 2 minutes.
The report does not include information about the launch, but it is described, with some images, in the attached slideshow.
Thank you to the Parallax Propeller community for all your hard work and amazing bits of code. You are all given credit in my report if I made use of your code in some way. I have attached my code too. I am afraid it is not very neat or polished or organised, but it might be useful to someone attempting this in future.
Comments
I look forward to reading your write up.
I don't think I know of any other Parallax Propellers being used on a near space launch.
Hopefully your payload will be found.
I hope you keep us informed about SUNSET v2.
I would really like to do something like this someday. I hope to learn from what you've done.
Thank you for taking time to share your documentation.
I'm very impressed by the thoroughness of both your planning and your execution. 'Very nicely done and documented! As a bonus, your project really shows off the capabilities of the Propeller.
-Phil
Nice work.
Some question on one time problems?.
On Yours PCB in slide show I can't see any protecting Capacitor on Battery side - My guess That shorted theirs life to much as all Batteries are very sensitive to AC transients.
To protect for that You need one 100nF and one Tantalum at least 20-30uF as near Battery wires as possible.
Very nicely done. I especially like impact and landing tests using eggs inside a pool noodle. Very resourceful.
Peter
I wonder if maybe your batteries got too cold?
I took a really quick look at your code, and it appears that for temperature, you are converting the RCTime value back to an actual temperature. This is of interest to me, because I have several projects using thermistors and I have yet to utilize actual temperatures. I am just using known upper and lower limit RCTime values for my projects.
Last summer myself and 3 other Cal Poly San Luis Obispo students preformed a similar experiment as an extracurricular project through the IEEE club. We used the propeller platform from Gadget Gangster as our base platform, and an Atmel AVR device to implement the APRS protocol. 2 secondary boards were designed. The first housed a GPS module, XBee Pro XSC, and the AVR, and the other implemented an analog interface to the propeller (ADC with filtered inputs and selectable gain). The analog interface board also housed an Intersema MS5534 barometric sensor.
I am interested in your code that implements the APRS protocol. I would like to make our current project into a completely propeller powered design.
Below are a few pics, and I have a lot more to share, but need an appropriate place to upload what I have. If anyone can direct me where to do this, I will upload the rest.
Sorry to hear you were unable to retrieve your palyload. I think Rayman brings up an excellent point. Batteries have a hard time supplying power at such cold temperatures. It happened to me on my fifth mission at 119,800 ft (maybe flying at night isn't such a good idea after all). Fortunately I had a redundant tracking device with a redundant power supply that did not fail. Once my payload was on the ground and the batteries had a chance to warm up, everything worked fine again.
Can't wait to hear how SUNSET II performs.