[Paul] is very up-front about the realities of his $25 Satellite Tracker, which aims a tape measure yagi antenna at a satellite of choice and keeps it tracking the satellite as it moves overhead. Does it work? Yes! Is it cheap? Of course! Is it useful? Well… did we mention it works and it’s cheap?
When [Paul] found himself wanting to see how cheaply he could make a satellite tracker he already had an RTL-SDR (which we have seen used for satellite communication before) and a yagi antenna made out of a tape measure, but wanted some way to automatically point the antenna at a satellite as it moved across the sky. He also wanted to see just how economically it could be done. Turns out that with some parts from China and code from SatNOGS (open-source satellite tracking network project and winner of the 2014 Hackaday Prize) you have most of what you need! A few modifications were still needed, and [Paul] describes them all in detail.
So is a $25 Satellite Tracker useful? As [Paul] says, “Probably not.” He explains, “Most people want satellite trackers so that they can put them outside and then control the antenna from inside, which someone probably can’t do with mine unless they live in a really nice place or build a radome. […] Driving somewhere, setting it up correctly (which involves reprogramming the Arduino for every satellite), and then sitting around is pretty much the opposite of useful.”
It might not be the most practical but it works, it’s cool, he learned a lot, and he wrote up the entire process for others to learn from or duplicate. If that’s not useful, we don’t know what is.
Satellite tracking is the focus of some interesting projects. We’ve even seen a project that points out satellite positions by shining a laser into the sky.
Students of the Samara State Aerospace University are having trouble getting a signal from their satellite, SamSat-218D. They are now reaching out to the radio amateur community, inviting everybody with sufficiently sensitive
UHF VHF band (144 MHz) equipment to help by listening to SamSat-218D. The satellite was entirely built by students and went into space on board of a Soyuz-2 rocket on April 26, 2016. This is their call (translated by Google):
Continue reading “Can you hear SamSat-218D?”
Ham radio operators are curious beasts. They’ll go to great lengths to make that critical contact, and making sure their directional antennas are pointing the right way can be a big part of punching through. Of course there are commercial antenna rotators out there, but hams also like to build their own gear, like this Raspberry Pi-controlled 2-axis rotator.
[wilho]’s main motivation for this build seems to have been the sad state of the art in commercial 2-axis rotators, which seems firmly mired in the 90s. Eschewing the analog pot sensors on DC brushed motors that seem to dominate the COTS market, [wilho] went with steppers and stout gearboxes for the moving gear. Feedback on the axes comes from 10-bit absolute encoders, and an MPU9250 9-axis IMU makes sure he knows exactly where the antenna is pointing with respect to both compass heading and elevation. A mast-mounted Rasp Pi controls everything and talks through a REST API to custom software that can return the antenna to custom set-points or track the moon, satellites, or the ISS. It’s a very impressive bit of kit that’s sure to drive your home-owners association bonkers.
For another 2-axis antenna positioner, check out 2015 Hackaday Prize finalist SATNOGS.
Continue reading “Track Satellites with a 2-axis Antenna Positioner”
Here’s an interesting thought: it’s possible to build a cubesat for perhaps ten thousand dollars, and hitch a ride on a launch for free thanks to a NASA outreach program. Tracking that satellite along its entire orbit would require dozens of ground stations, all equipped with antennas, USB TV tuners, and a connection to the Internet. It’s actually more expensive to build and launch a cubesat than it costs to build a network of ground stations to get reasonably real-time telemetry from a cubesat. The future is awesome and weird, it seems.
This is the observation the guys behind SatNOGS have made. They’re developing a platform for a completely open source ground station network, with the idea being people an institutions along every longitude and latitude would build a simple satellite tracking antenna mount, connect it to the Internet, and become part of an open source Near Space Network, capable of receiving telemetry from any one of the small cubesats whizzing around in low earth orbit.
Despite being what is probably one of the most ambitious and far-reaching projects in open source hardware, the design of the system is relatively simple: the hardware is a 3D printed alt-az mount, capable of pointing a pair of antennas anywhere in the sky. The stepper motor driver board is based on the Arduino, and the computer running each antenna node is powered by a BeagleBone Black or a WR703N router. The antenna receiver is, of course, an RTL-SDR dongle, capable of listening to all the common cubesat bands. Even the software is derived from open source projects. Tracking a satellite across the sky can be calculated with GPredict, and the team is working on an observation scheduling and management system that combines multiple ground stations for coverage across the globe.
It’s a great idea, crowdsourcing satellite tracking from people around the globe, and something that could be used by hundreds of institutions lucky enough to launch a small cube of electronics into orbit.
The project featured in this post is an entry in The Hackaday Prize. Build something awesome and win a trip to space or hundreds of other prizes.