Tag: groundstations

SatNOGS Activity Update 2019-01-27

Akademisk Radioklubb Repair LA1NGS Ground Station

This week a story from Trondheim Norway. We love this story because it shows the fabulous co-operative nature of the SatNOGS community. Established in 1923 Akademisk Radioklubb is the oldest amateur radio group in Norway. The group has been using the LA1NGS SatNOGS station to schedule observations. Owned by NTNU Small Satellite Lab and Orbit NTNU  they noticed that the rotator on LA1NGS had stopped working. Keen to help members of the Akademisk Radioklubb reached out and helped them replace the worn Yaesu G-5500 rotor with a new SPID SPX-02 . As reward they were given the G-5500 which they hope to refurbish and build their own station. More detail and lots of pictures on the Akademisk Radioklub blog.

Ground Station Hardware Report

Fabulous contributor Azisi has produced a useful report over on the Libre Space Foundation Community discussion forum. It collates the various hardware projects relating to creating ground station hardware and gives links to the repositories and to documentation. There is a real range of projects here from the rotator assembly through to small PCB notch filter to remove unwanted FM bands. Check out the post and get building here!

ARISS Contact Ashbury College Junior School, Ottawa Canada

Once again ground stations on the SatNOGS network captured a great ARISS conversation between a junior school and the international space station. For details of the contact and also to hear the observations themselves, be sure to check out the post on the Libre Space Foundation discussion forum.

Data from space, the libre way

SatNOGS is maintained by the Libre Space Foundation, a non-profit built to develop and promote open source space technologies and open access to space-related data. The passion we have for space and open source is what drives us, and we are proud of the community that has been built around SatNOGS. Over the past four years of development, the SatNOGS community has grown to more than 100 ground stations around the world with more than 2000 satellite observations per day.

On November 27th, Amazon announced the AWS Ground Station service. Like other companies who are currently operating ground stations as a service, this will allow satellite operators to receive their data using proprietary and closed-source technologies. The SatNOGS community is focused on building a ground station network that provides downlinked satellite data to researchers and operators worldwide, in an open way and free of charge. As we have for four years, SatNOGS will continue to serve organizations and missions that value the openness of science and data.

With Amazon and other companies entering this space, our vision for SatNOGS remains the same: to advance open technologies and open data for space by creating the best and largest open source satellite ground station network.

We will continue to develop in the open, and invite all space and satellite enthusiasts to join us!

SatNOGS News – January 2017

SatNOGS community has been busy over the last couple of months, with many exciting updates on projects to share with you!

 

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Rotator v3.1

First and foremost, the 3.1 version of the SatNOGS rotator is soon to be finalized. If you are already working with a v3 keep in mind that upgrading to 3.1 is pretty straightforward, on the meantime feel free to share your build progress or finished ground stations with our community We got have some stickers to send to SatNOGS ground station operators. We really hope that lot’s of people get to install their own v3.1 rotator and hook up to the SatNOGS network, and we are working on a way to get the v3.1 rotator design to as many people as possible.


New UHF antenna

We published a new UHF 8 turn helical antenna design.  Documentation and step-by-step build process is now public so everyone interested can build one on their own, using readily available tools and materials.


Updates on SatNOGS DB

Our crowd-sourced satellite database, SatNOGS DB, is expanding and will soon be powering Csete’s gpredict through it’s API. In the meantime we deployed new functionality that allows SatNOGS DB to visualize telemetry data captured using the SatNOGS Network of ground stations.


Events

We really appreciate people participating in the SatNOGS project, either in our community website,  our IRC/Matrix chatroom, the SatNOGS Wiki, populating the SatNOGS database and our source code repositories but we also enjoy meeting people interested in SatNOGS in person.

linuxconfauLast week on Linux.conf.au taking place in Hobart,Australia, Scott Bragg’s gave a great talk titled “Decoding Satellites With SatNOGS“. It was a great overview of the SatNOGS project and the ways you can get involved.

shrAijm8_400x400Since most of the core SatNOGS team lives in Europe most of us will attend FOSDEM in Brussels,Belgium this February. There Manolis Surligas is giving a talk “SDR for Space the Open Way” focusing on the Software Defined Radio RF frontend and the GNU Radio module operating it and will be introduced in the coming versions of the SatNOGS client.

Stay tuned for more detailed updates, and as always … keep hunting satellites!

 

 

SatNOGS #1 in Athens, Greece

10 days ago we deployed a SatNOGS v2 on top of hackerspace.gr in Athens, Greece. This is the first SatNOGS deployed on the field and we couldn’t help but thinking that this is a huge milestone and brings great pride to the team!

SatNOGS #1

(obviously the front cap is closed at the finished deployment)

The deployment was pretty straightforward, with one UHF helical antenna (our VHF is still up for matching) and no SatNOGS client controlling it (still under development for connection to Network). We simply controlled it with gPredict and Gqrx. POE for powering it up and minimal weather shielding (just some silicone on and around the bolts of the box)

We were able to track and record many different satellite passes and we encountered some software issues with our arduino homing code (see our post on community forum for details) which we hotfixed.

Congratulations to the whole SatNOGS team for the first deployment!

SatNOGS now equipped with Diplexer

We’ve been thinking for some time that there is no need to install two separate RTL-SDR dongles to cover both VHF and UHF. It increases power consumption on WR703N without actually having any benefit, as using two dongles simultaneously is limited by the CPU power and network bandwidth.

A diplexer would allow the connection of a single dongle on both antennas. After studying the theory behind filters, we decided to implement a pair of Chebyshev filters. This type of filter has very steep roll-off and the maximum ripple can be a design parameter.

The two filters, a high-pass to attenuate the VHF band and a low-pass to attenuate the UHF band, should be crossing at exactly 288MHz@-3dB. Attenuation on each band should be at least 50dB. We calculated that a 9-pole Chabyshev filter would match these requirements and started designing a prototype on Qucs. Qucs is an open source circuit simulator which helped us verify that our calculations are correct.

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LPF

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The LPF has a maximum insertion loss of 0.4dB in VHF. The attenuation in UHF is more that 60dB. Some ripple can be observed on the chart, but it should not affect reception of narrow band signals.

HPF

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The HPF has a maximum insertion loss of 0.2 dB in UHF. The attenuation in VHF is more that 80dB.

Special care has been taken to ensure minimal cross-talk between the two filters. The bottom layer of the PCB is a complete ground plane and two copper shieldings have been solder on top of each filter.

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Please note, that this diplexer can be used only for receiving. For transmission, a higher grade of components (high voltage caps, high current inductors) should be used.

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All source files can be found in our github repo here.

More pics from the diplexer can be found here.

Extreme conditions considerations – Radome

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.8103441414183780536

 

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.2728161414186279380

 

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.

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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!1304161414187677993

 

Designs (CAD and STLs) are available in our repo, and once the shrink wrap arrives we will be posting a detailed how-to guide.

 

 

Portability for SatNOGS ground station

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.4056311414017834614

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!

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SatNOGS going Helix

An important part of the instrumentation of our ground station is the Antennas. Early on the SatNOGS team designed and constructed 2 Yagis for UHF and VHF bands. The UHF Yagi design was essentially a cross Yagi design trying to address the circular polarization issue. Based on the experimental operation of the ground station we were sure we can do something better.

Satellites are tumbling and turning, thus if the transmission of the transponder is done in a single dimension polarization you better match this polarity to get the optimum gain. (if not you will loose 30dB) (check here for details). We decided that a Helical antenna would give SatNOGS a better chance for an optimal reception, so we needed to design, document and build one.

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There are a couple of theoretical models for Axial-mode Helical Antennas. Most notable are the Emerson one and the Kraus. We decided to go for Emerson, given our wavelengths, construction constrains and overall size. As we were going for UHF band 437Mhz seemed like a popular frequency for satellite communications and we centered around it. As for the circular polarization we designed a Left-Hand one (as we already had a Right-hand cross-Yagi design).

Dimitris worked on a modular and extensible design that can be used on other bands too. 3D printed parts and off the self items is the classical recipe that we followed. The result is a sturdy and easy to construct antenna. Initial tests are showing improvements compared to our cross-yagi UHF which is a win!

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The design can be found here, bill of materials here and a detailed documentation on how to build here.

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Optimization of the antenna is crucial. We invested considerable amount of time towards that and there is always room for improvement in matching, constructions and details [1]. More NEC calculations will follow and we expect more fixes as we go.

[1] http://users.ece.gatech.edu/~az30/Downloads/HelixAPMagazineSubmission.pdf

SatNOGS Ground Station v2

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The time we’ve all been waiting for, has come. We are proud to release v2 of SatNOGS Ground Station (Tracking Box) with many upgrades and fixes from the previous version. Notably:

  • Redesigned Axis Gear Assemblies. They are now smaller, more robust and reliable based around a much more powerful NEMA 17 Stepper Motor. The two assemblies are now structurally connected, making the whole assembly much more rigid. Also we redesigned the Worm Gear for improved printability on 3D printers.
  • Integrated electronics. We designed and built a new PCB to house all electronics (Arduino, and Stepper Drivers) along with an additional PCB as a PSU for voltage regulation and neater cable management. (see previous post)
  • Reworked stepper driving code, featuring a much cleaner code, acceleration and deceleration in movement, stop functions and early opto-homing support. (see previous post)

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Tripod and On-board computer (TP-Link) stayed the same, with developments on them coming down the road.

A detailed Bill of Materials is available here.

We have also compiled a detailed construction guide, with step by step instructions on how to assemble the Ground Station Tracking box for both Mechanical and Electronics components.

http://satnogs.dozuki.com/c/SatNOGS_Hardware

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All Designs and 3D printable files can be found here and all PCB files for our electronics shields can be found here.

Development does not stop with v2, and we are already working on the homing/zeroing code that will enable the homing parts we included in v2 to function. Moreover based on more testing we are applying to v2 and feedback from the community, we expect minor fixes to be released soon.

 

We can’t wait to see v2 out there, built by others, so get started and/or provide feedback!