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SATRAN - Satellite Tracking Antenna

3D-printed, wifi-enabled and android controlled antenna rotator.

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A compact satellite antenna tracker with android app. Available within the next few months as an affordable kit, but it's also possible to 3D-print the open source files yourself!

This is a continuation of an old project of mine, when I built a simple satellite antenna tracker with an android app that calculates the position of any satellite using its "kepler elements", and controlling the Az-El antenna rotator to track it across the sky. During a few late nights together with two other ham operators, we built a crappy but functional prototype from spare parts. Now some years later, I decided to redesign it from the ground up as an affordable and easy to use kit.

Controller

The onboard microprocessor is an ESP8266 NodeMCU board with wifi-capability that can be controlled manually in a web-interface or automatically through an android app.

Motion will happen with the help of two Nema17 stepper motors, and the rotator has a platform that allows for many different kinds of antennas or a small satellite dish.

Time schedule

Kits should be available for purchase starting in february/march 2021, and STL-files for 3D-printing will be offered for free online for those who can 3D-print themselves. 

If you have any request or feedback, please let me know! 

/  Daniel  www.danaco.se

SATRAN-BOM_2021-01-05.pdf

Bill of materials

Adobe Portable Document Format - 2.05 MB - 01/07/2021 at 13:57

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  • The new website

    Daniel Nikolajsen5 days ago 0 comments

    Since all the info and data for the Satran has grown, as has the followers. Therefore I couldnt host it all on my own website, so this week I put together a new website that is now available at www.satran.io

    Check it out!

  • The first kits have been shipped

    Daniel Nikolajsen02/16/2021 at 14:48 0 comments

    I can hardly believe its true, but what was just a hobby project a few months ago is now the beginning of a new business. Today I modestly opened the webshop and the first kits sold out in minutes and are now on their way to early adopters across europe. Since I couldnt afford to buy components for more kits the stock was very limited, but things will ramp up quickly.

    The next production run has already started, which will consist of around 50 complete kits. My apartment will surely get cramped, but its worth it. Even if I won't get rich on the kits, its an amazing feeling to make money from your passion. And to be honest, I think my passion for the tech is what people want to be part of. Also, since I was more or less unemployed last year this has been a true salvation.

    No matter if you're planning on buying or just like to follow and share the project, I can't even describe how thankful I am to you all. You are the best!!! 

  • A great project deserves a good logo

    Daniel Nikolajsen02/14/2021 at 21:25 0 comments

    Since I'm planning for a dedicated website, a nice logo is a must. This is the first draft, but it turned out quite nice. But perhaps make it even more minimalistic to look good even in smaller sizes or with less color.

  • Drape mold for plastic cover

    Daniel Nikolajsen02/12/2021 at 06:48 0 comments

    The last parts are almost finished. The sides and top cover will be made of CNC-cut ABS plastic sheets that should arrive from the manufacturer on monday. Since my own CNC mill broke down I had to find a local producer instead, but that will pay off anyways when I scale up from a handful to perhaps a hundred kits in each run. 

    The top cover then needs to be thermoformed in a U-sized shape. That is why I'm making a mold right now, on which I can drape the heated plastic. Just put the sheet in an oven for a few minutes, take it out and bend it around the mold. I'll try to hold it in place with two straps as you can se in the pic. Will it work? Time will tell.

  • It's getting closer

    Daniel Nikolajsen02/08/2021 at 13:30 0 comments

    After the previous challenge of finding suitable plastic sheets, I finally stumbled upon a local manufacturer who could assist me not only with the material, but also CNC-mill the parts at a reasonable price which saves me a lot of time.

    That means the very last parts are soon in stock. What intense months it has been.. I can hardly believe that its finally done. There's even some time to tweak the firmware and check a few extra times to make sure that there arent any bugs before I open up shop. Because when it's shipped it's out of my hands and any critical errors means I have to send the customer a new board.

    Exciting times.

  • It's always the simple stuff

    Daniel Nikolajsen02/04/2021 at 08:13 0 comments

    Well, production was going quite smoothly. My goal was to offer the first kits this or the next week, but of course one of the last parts are giving me a huge headache. To make it even more entertaining, it's the most simple and inexpensive of all; 3mm plastic sheets...

    You would think that finding simple sheets of black plastic should be easy. But apparently not in Sweden. It's litterally impossible to find a supplier that can sell you anything less than 500kg!! And importing takes way too much time. But I might have found a retailer in germany that should be able to help, even if it adds a week or two of production.

    Also on top of all, the hard drive crashed in my beloved CNC-machine. I have already ordered a new disc, but finding all the correct settings and calibrations again makes me wanna cry. Whyyyyy?!!?!

    Oh well, you just have to roll up your sleeves... To swear a little also helps.

  • The first production run

    Daniel Nikolajsen02/01/2021 at 11:22 0 comments

    Production has been ongoing for some time now, and there's only a few more components to arrive by post before I can offer customers the first kits. However, the first batch won't be as big as I would like, but its a good start. If you count all individual components, there are approx 150pcs for a single kit. Some needs to be soldered, some needs to be 3D-printed, while others just needs to be counted and put into bags. On the schedule today... shortening of the stepper motor cables.

  • Checkout the video!

    Daniel Nikolajsen01/30/2021 at 20:29 0 comments

    The prototype is working like a charm, even if some bug fixes and tweking remains. But just to tease you a little, I put together this nice video for my youtube channel...

  • Where's the sat at?!

    Daniel Nikolajsen01/22/2021 at 15:44 0 comments

    What do you think? Its starting to look quite nice, with my 70cm yagi added. The weight is somewhat balanced now with my improvised weight in the rear of the antenna. Next week it's time to shoot a video, but now a well earned beer is top of my priorities since this week has been 16 hour work days. cheers!

  • Lesson learnt on stepper motors

    Daniel Nikolajsen01/22/2021 at 06:12 0 comments

    I am now in the final tweaking stage of the project. Getting sensors to work mostly without any glitch, and tuning the stepper drivers to make the torque as good as possible without overheating or breaking anything.

    For almost a full day I struggled with getting any decent torque from my stepper motors. The A4988 driver has a built in circuit to limit the current with a trimpot to adjust it, but no matter what I did the motors gave off some crazy whining sound and never took more than about 200mA, and were so weak that I easily could halt the motors with my fingers.

    But then, after a fresh cup of coffee, I read the datasheet for the motor and realised... Resistance! The motors I had were 10 ohms. So I switched to 2.8ohm motors instead, and bam! A full 1 amp current. Now the rotor should be able to turn the antenna without any issue, but the exact specs are still to be tested...

    We're getting somewhere!

    Also the response I have gotten from all over the world has been amazing, I cant thank you all enough. From more or less being unemployed due to covid last year, I am now working day and night to finish the design. Lots of people are requesting to buy the kits, and if you havent already - subscribe to the newsletter on my site to get reminded when stuff gets released, because the first kits and circuit boards will probably sell out in minutes. Also, thanks to you and others who have donated to the project I will try my best to keep as much as possible under open source, including the android app I am developing.

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Discussions

Mihai S wrote 02/12/2021 at 19:25 point

HI, for the past 3 weeks I've been printing like crazy different rotors projects, I like your project but where is the firmware? github?

  Are you sure? yes | no

Daniel Nikolajsen wrote 02/12/2021 at 20:15 point

Shop will open in approx a week where you can buy control board with firmware preinstalled (EU customers only, exports will begin in about a month)

  Are you sure? yes | no

k.jurczok wrote 02/05/2021 at 09:15 point

good luck with adversity. I believe that the failure will be managed quickly :)

  Are you sure? yes | no

k.jurczok wrote 02/01/2021 at 09:57 point

Hi!

What is maximum load of this rotor?

  Are you sure? yes | no

Daniel Nikolajsen wrote 02/17/2021 at 06:43 point

It's built for smaller antennas, the exact weight limit is still to be tested.

  Are you sure? yes | no

jed wrote 01/27/2021 at 15:47 point

Perhaps you understand this, but your 10 ohm steppers take a higher voltage to get to 1A. The A4988 driver carriers that look like what you are using are good for up to 35V and more voltage equates to quicker ramp time to the correct current. Your 9V is near the 8V MINIMUM for these drivers. Also, remember you can only measure stepper current when they are HOLDING and not turning. If you'd rather use 10 ohm steppers, try 24V.

What a great project! Best of luck!

  Are you sure? yes | no

Daniel Nikolajsen wrote 01/27/2021 at 16:07 point

Exactly I didnt realise first that it was 10ohm motors I had. Since the entire board needs to run on a single power supply it needs to be at 8-10 volt because of the NodeMCU and A4988. Otherwise the controller board needs to be redesigned with extra voltage control, and because of the cramped space in the housing the entire hardware probably would need to be redesigned too. Thx!

  Are you sure? yes | no

Thomas Daniels wrote 01/18/2021 at 16:38 point

Hi, this looks very interesting and affordable. I have a few questions: Will this rotator be strong enough to carry a 2m and a 70 cm XYagi, each about 1,5m long? Is it watertight enough for permanent assembly outside? Can it be controlled by connecting to an IP-address using any browser? (I do not have any androids here). And how much will it be? If I understand correctly, you are still in the development process?

  Are you sure? yes | no

Daniel Nikolajsen wrote 01/22/2021 at 06:17 point

Hi, a double antenna system with such large arrays I think should be too much for this design unfortunately. Also it is not completely weathertight and durable enough to withstand hard wind, so not recommended for prolonged outdoor use.

 But if I get enough response I hope to make a better version (but more expensive) later on made from aluminium, stronger motors etc. The first version thats still in development is made to be a cheap and simple, costing from around 60USD for only the controller board up to perhaps up to 230 USD for a full kit. The first will probably be available for sale early february. 

It can be controlled via IP/browser but since the positioning (calculating the direction) is done in the app, you need some other software to know where to point the rotator. Perhaps Gpredict (win) and others could work.

  Are you sure? yes | no

jcwren wrote 01/18/2021 at 00:15 point

It's an interesting rotator design and is nice and compact. My concern is the amount of load you're putting on the gear train as the antenna changes azimuth. If the antenna is balanced and the antenna is pointing at the horizon, there's no stress. But as the azimuth increases, the load dramatically increases as it's not balanced on the pivot point as it is with a conventional antenna rotator. When the azimuth is 90 degrees, the gear train is supporting the full weight of the antenna and it's increased because it's cantilevered. What are your thoughts about that?

  Are you sure? yes | no

Daniel Nikolajsen wrote 01/18/2021 at 05:39 point

That's correct, it's not perfectly balanced. But the design isn't made for use with any large 2meter yagi antennas that weigh many kilograms, but for smaller types perhaps a 70cm yagi or some compact LPDA type.

Also when the antenna is in zenith (pointing straight up), the entire antenna is offset from the axle but only with a few inches. This means that the torque on the elevation worm gear is actually not that large.

But changing the axle (M8 threaded rod) to a longer one and putting a mount directly on the axle shouldnt be a problem either if you prefer that approach instead. That should also be preferred if you want to have two antennas - one on each side.

  Are you sure? yes | no

Tom wrote 02/03/2021 at 21:31 point

I can't see it struggling to drive something like this: 

http://www.schnizer.com/SOTAblog/equipment/lightweight-2m-yagi-sota/

  Are you sure? yes | no

Daniel Nikolajsen wrote 02/09/2021 at 08:02 point

No Tom, that yagi shouldnt be any problem, also in my video (and on all the boards I'll ship) the stepper drivers are only tuned to around half capacity to be sure not to overheat anything. With tweaking you could probably more than double the torque without any issues.

  Are you sure? yes | no

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