Balloon Project Overview
My interest in High Altitude Ballooning started when I saw a video by Night Crew Labs, a youtube channel which specializes in making HAB videos. After watching the video I was hooked on the idea of creating a High Altitude Balloon and decided to begin further researching the topic. I quickly found out that HABs were very common and there were many forums and enthusiasts dedicated to educating the public on how to learn and launch HABs. From here I quickly began figuring out the equipment and its cost and began preparing to purchase these items. Luckily I already owned a GoPro, which was likely to be the most expensive part of the project. The main issue I was having was that the cost of most commercially available GPS trackers was more expensive than I could afford. In addition to this many such trackers require year-long subscriptions which can often exceed the cost of the tracker itself. For this reason, my first project with HAB was to develop a GPS tracker for my HAB.
HAB Version 1
As mentioned above in my first balloon project, my main goal was to develop a primary tracking system for the HAB. To start this process I began working to find GPS modules that work for the Arduino. Ultimately I found the Ada-fruit Ultimate GPS which was used by other people interested in HABs because of this GPS's ability to operate at above 65,000ft, where many other GPS systems cut quit working. Getting familiar with this system was relatively straight forward and details into this process can be found in my tutorials on GPS.
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Now with a working GPS, I needed a method to relay information from the balloon back to a ground station. Many hobbyists use the Automatic Packet Reporting System (APRS) which is a digital communications system which can be used throughout the world. Essentially this system relies on many amateur stations to receive and route the information; making this information available to you. Unfortunately, this method requires users to have an Amateur Radio License(ARL). Today I would strongly encourage anyone interested in an ARL to get one, but at that time I was uninterested. Through the following searches, I eventually was able to locate the RFD900+ radio modem. This modem was developed for long-range telemetry but had previously been used by a handful of HAB enthusiasts. The greatest benefit of the RFD900 was that it does not require any license to use. It does have some drawbacks though, unlike APRS the RFD900 is only made up of two modems: one on the balloon and one on the ground. For this reason, the modems must stay within range of each other for communications to not be lost. Despite this, I decided to use the RFD900, figuring that I could always follow the balloon in real-time using the balloons GPS coordinates. After this decision, I wrote the software to transmit and receive the balloon's GPS coordinates. I also decided to 3d print antenna holders so that I could follow the balloon in a car while tracking the balloon. This decision allowed the RFD900 to stay in range throughout the flight, even when using dipole antennas.
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Because the balloon had not been tested at high-altitudes, for the first test I chose to not include the GoPro in the Balloon's payload. Despite my concerns, the first launch went well and although I did encounter some bugs in the program the balloon was recovered successfully. As described in my tutorials for these launches I used google earth to track my balloons location live. The python software I wrote also recorded all of the reported coordinates. Using this data I was able to create a plot of the balloon's flight which can be seen below.
HAB Version 2
In the second version of the balloon, I addressed some of the issues encountered in the first balloon. The main problem being that the method used to store GPS coordinates, was sometimes causing the GPS coordinates to become corrupted. During the first balloons, launch there had been moments where according to the balloons, data it had been in Spain. This turned out to be a relatively simple fix and was remedied with modest changes to the Python Script. In addition to this, I also discovered that the balloon had lost its GPS signal at around 65,000 which was not supposed to happen with the Adafruit GPS. Despite that the GPS momentarily lost its signal the RFD900 connection was never severed and after the balloon returned to altitudes less than 65,000 feet I was again able to receive coordinates. For this reason, rather than opting to get a new GPS I decided to add a secondary balloon tracker. To do this I used an Iphone's find me function as well as an Arduino script to ensure the phone stayed off while at high altitudes. With the relative success of the primary tracker from the 1st balloon along with the addition of the secondary tracker, I felt comfortable enough to attach a GoPro onto the balloon. During this second launch I ran into virtually no issues during the balloon's flight and I was able to watch the balloon as it parachuted out of the sky. Unfortunately, the balloon parachuted straight into a cornfield which meant it took two hours of searching to actually find the balloon. Despite, this I was ecstatic to view the video that had been recorded from the balloon. Some of the video from this launch can be seen below.
HAB Version 3 and beyond
The third version of HAB is currently in development. The primary change in this balloon is switching from using Arduino to instead use an ST microcontroller. For the third balloon, the ultimate goal is to create an antenna array which has a powerful enough gain to be able to track the balloon for the majority of its flight. To be able to create signals strong enough to communicate over the large distances required in this project I will likely have to get an Amateur Radio License (ARL). Despite this, I am first trying to create an antenna array which can measure the strength of the signal on multiple antennas. This array will then use these measurements to orient itself in the most ideal direction. Ideally, this ability will make it possible to use high gain antennas, preventing me from needing more power, which would require an ARL. Already this project has required that I learn how to reprogram the software on the RFD900+ radio. The microcontroller in the RFD900+ is a SiLabs 1030, so for this project, I have now become familiar with both the ST32 line and the Silabs 1020/1030 uC. Ultimately, the ST uC will be in charge of controlling stepper motors to turn the array and transmitting received data to a computer. Meanwhile, the Silabs 1020/1030 will primarily measure the signal strength values on the antennas and transmit these to the ST uC. Additionally, the antenna array and antennas are all being constructed by me. Currently, a mixture of store-bought and 3d printed components are being used to create the antenna array holder. The antenna's themselves are currently planned to be high gain Yagi Antennas, although depending on how testing goes with these antennas I may construct patch array antennas instead. Tutorials on all of these subjects are available on this site and more will continue to be posted as work continues. Following completion and testing of the antenna array, I would also like to add support to the array for 1.2 GHz first-person view streaming so that I can follow watch the balloon's flight live. This will likely be something that is done in the fourth rendition of the balloon. Finally, for balloon 5 I would like to replace the mechanically steerable antenna with a phased array steerable antenna.