15 hours ago •
In order to achieve global coverage, a network of Ground Stations would have to have nodes in places that are not entirely friendly environments. Desert hot, ice cold, gusty, monsoon rainy, mountain dry and forest humid could be some descriptions of possible locations SatNOGS would have to survive in.
Apart from the obvious networking considerations (internet connection and power) which are not in the scope of our project (and are dealt with existing solutions), SatNOGS has some physical constrains, especially around wind and water.
The relatively compact design, our current antennas and the targeted IP55 protection marking are indeed a slight advantage on moderate wind and rainy situations, but we had to do more to ensure reliable operations on rainy and windy hilltops and locations.
The way to protect antenna tracking mechanisms (especially dish antennas but not only) has been long known in the industry and in military. The name of it Radome (Radar-Dome). Radomes provide weather protection (ice, heat, rain, wind) especially combined with an environmental control system, and ensure uninterrupted operation for moving tracking mechanisms.
After extensive search on the webz we could not find any DIY and/or Open project for a Radome, so we decided to design, build and document one for SatNOGS.
We started with the desired shape and size. A geodesic dome (3V frequency) provides a good approximation of a sphere (less air drag) while not requiring large amounts of material. For the size, we modeled SatNOGS with a typical antenna setup (Helical and Yagi) and calculated the extremes. We ended up with a sphere of 1.5m radius, 1.2m from the ground.
The material selected for construction is PVC tubes for struts (cheap and light-weigth) and ABS connectors (3D printable and durable). The Base is an aluminum (L channel) pentagon that can be bolted on the ground. It is important to emphasize that all materials (except the base pentagon) are non-conductive and dielectric. If Aluminum (or any other metal) was to be used, Quasi-Random patterns would have to mandate the design to avoid interference with the RF signals. For the outer surface many materials were considered, and Shrink Wrap seems to be the most cost-effective, easily applied and durable solution (check here for examples).
Gathering all materials is not hard, especially when you have access to a 3D printer. The overall cost is just below 130 USD.
Construction is pretty straightforward. You start with the pentagon and work your way to the middle. Then you start from the top working your way down, until you are left with two hemispheres. Once those are connected in place you lay out the shrink wrap and using a heat gun you apply it in place.
Depending on the materials you would choose, some bonding might be needed between connectors and struts. (epoxy glue would do just fine). Shrink Wrap would take care of the final rigidity of the structure.
Unfortunately shipping times for shrink wrap as not as fast as we expected so we only finished the skeleton of the radome and we are waiting for the final layer to apply it by next week. (an new log will be posted for this!)
The end result is really impressive taking into account resources used. The structure is really light-weight so 2 people can fit it on SatNOGS by lifting it and lowering it on top of it. Then you would secure the pentagon on the ground and you are ready to go!
Designs (CAD and STLs) are available in our repo, and once the shrink wrap arrives we will be posting a detailed how-to guide.
3 days ago •
Most of the times you would want your ground station to be stable. Secured on a metal beam on top of a building, protected, homed and zeroed where no-one and nothing could disturb it. That is the ideal situation.
For those of us though that like adventures and want to carry a ground station with us on a field trip (DXing, Iridium flare hunts or even mountaineering) having SatNOGS be portable would be a huge advantage.
Luckily (actually... by design) the main gear mechanical assembly is a lightweight box with 3 beams sticking out. Easily carried even as a backpack. Antennas can be detached and especially the yagi ones, disassembled and carried as a long beam. But where would you put your ground station on? That called for a tripod!
We did have a tripod design (v1) early on (check designs here) but it was not really easily constructed and not easily deployable. So we focused on a new design.
Version 2 is much more easily constructed, considerably more stable and totally portable as it collapses in a single beam. We tested it dozens of times on the field over the past couple of weeks and it is stable enough to allow reliable operations for a typical SatNOGS setup (UHF and VHF antennas mounted too). The cost of it? Aprox 15 USD :)
Designs and models can be found in our github repo here.
Bill of materials here. And guess what? We love documentation :) So here are some step by step instructions to build it yourself!
18 days ago •
Continuing the development of SatNOGS Network, we focused on enhancing the observation results page. Check out how it looks overall:
What is new?
The new timeline view gives a quick overview on the data that each ground station collected within the observation timeframe. On the left you can see the list of the Ground Stations that participated in the observation and on the right you can check the timeblocks each ground station got data. We used the nice d3-timeline js plugin for it.
Each data that is associated with an observation is displayed in a new panel-based section. The data we collect can be either text (decoded messages) or sound (available for further processing). We dealt with the hardest one first. We used Wavesurfer.js to visualize the waveform (HTML5, WebAudio and Canvas FTW!) and added the ability for playback directly in the browser. A download link is also available.
The code for the implementation of the new views is already pushed in our repos. Soon we will be updating the dev instance with mock data so that you can check out the new functionality yourself.