Tracking CubeSats For $25

Cloverleaf Satellite Antenna Mounted on a Pole

CubeSats are tiny satellites which tag along as secondary payloads during launches. They have to weigh in at under 1.33 kg, and are often built at low cost. There’s even open source designs for these little spacecrafts. Over 800 CubeSats have been launched over the last few years, with many more launches scheduled in the near future.

[Thomas Cholakov] coupled a homemade cloverleaf antenna to a software-defined radio to track some of these satellites. The antenna is built out of copper-clad wire cut to the correct length to receive 437 MHz signals. Four loops are connected together and terminated to an RF connector.

This homebrew antenna is connected into a RTL-SDR dongle. The dongle picks up the beacon signals sent by the satellites and provides the data to a PC. Due to the motion of the satellites, their beacons can be easily identified by the Doppler shift of the frequency.

[Thomas] uses SDR Console to receive data from the satellites. While the demo only shows basic receiving, much more information on decoding these satellites can be found on the SDR Satellites website.

This looks like a fun weekend project, and probably the cheapest aerospace related project possible. After the break, watch the full video explaining how to build and set up the antenna and dongle.

11 thoughts on “Tracking CubeSats For $25

  1. I bought one of those Chinese rtl-sdr kits recently and thankfully I tested the USB stick before putting it together because it was dead out of the box! I’m still waiting for the replacement…

    1. I’m sure that you have already checked it, but if it included a USB cable then try another cable.
      I have a drawer full of defective USB cables which came with Chinese devices, including a rtl-sdr.

    2. Check out the Genuine (you can tell because it will have 2 screws on each end instead of 4, or follow the link if their site), RTL-SDR.COM V.3. Pretty good for $25 and it has GPIO pins inside.

  2. Aren’t most satellites now secondary payloads?

    In the very early days, it was one satellite per rocket. Then someone talked their way onto a launch, and OSCAR 1, the first amateur satellite, went up in December 1961 as the first secondary payload. That proved the value, so endless satellites have gone up as secondary payloads. It’s across the spectrum, though it certainly has allowed for launches of “amateur” satellites. On the other hand, there’s now o much demand that it’s harder to get a launch.

    Cubesats are just a small format variant, the tiny size meaning even more secondary payloads can go up per launch. So there’s less criteria needed to get a cubesat into orbit. Though I assume it allows for frivolous projects, at the expense of more important satellites. AMSAT gets a lot of cubesats into space, but there seems to be a stall on some long planned projects.


    1. By standardizing the size and weight of the satellite, cubesats are also easier to launch – they can use generic mounting hardware. A company called NanoRacks actually has a cubesat launcher on the ISS – they get brought up on resupply missions, mounted to the launcher, and sent off into low earth orbit.

      Makes mission integration much easier than for a typical satellite. It’s very cool stuff.

    2. There’s not much up there that you could call frivolous — getting a 1U cubesat to space still costs tens of thousands of dollars (TAANSTAFL, after all). The silly shit has mostly been done by launch providers with new rockets that nobody wants to trust payloads on (SpaceX’s cheese and Tesla, Rocket Lab’s disco ball). There are also quite a few almost-missionless cubesats built and flown primarily as student exercises, but those generally attempt to do something at least a tiny bit useful.

    3. Black,

      I don’t think your assumption is justified. Here’s why: If satellites are secondary payloads, then (aside from ISS missions and deep-space missions) what’s the primary? We’ve got a booming launch market, with launches happening regularly (the following link has the next three launches at the bottom – all in June 4-6: and all those launches have a satellite as their primary payload. I have no problem assuming that there’s a bunch of cubesats with them, but (last I heard) launch costs are typically shared by all satellites being launched. It’s Groupon for spaceflight – “We’ve already got a launch for an x-ton satellite, we’ve got y lbs of of capacity leftover on this launch, who wants to help share the costs?”

      More specifically addressing your comment about “harder to get a launch” – I don’t know, but would be unsurprised to hear, that the number of “big”/”important” satellites is the primary driver of that. I am unaware of many missions which launch “only” cubesats (found one – experimental last year: – the impression I get is that there are probably a ton of cubesats vying to hitch a ride the next time a “big” satellite goes up. And it probably is hard to get a rocket – we have numerous satellites already in orbit, and not only do we keep replacing them, but other people want to get their constellations up. So I’m not too surprised to hear that it can be a challenge to find a rocket to launch your satellite, but I don’t think that nanosats and cubesats are the root cause of that.

      If you’ve got a source on cubesats displacing regular satellites, by all means reply with it. But my current understanding is that they have allowed a substantial amount of cost-sharing (and therefore cost reduction for the big satellite launches) – basically a win-win for literally everyone. It’s cheaper to launch big satellites, it’s vastly cheaper to launch small satellites, and launch companies see increased business.

      Unless we hit some kind of Kessler Syndrome, anyway – but presumably the literal rocket scientists are keeping an eye on that!

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