Usually when we hear about someone making contact with astronauts in orbit, it’s an intentional contact between a ham on the ground and one of the licensed radio amateurs on the ISS. We don’t often see someone lucky enough to snag a conversation between ground controllers and a spacecraft en route to the ISS like this.
For [Tysonpower], this was all about being in the right place at the right time, as well as having the right equipment and the know-how to use it properly. Soyuz MS-12 launched from Baikonur on March 14 with cosmonaut [Aleksey Ovchinin] and NASA astronauts [Nick Hague] and [Kristina Koch] onboard, destined for the ISS after a six-hour flight. The lucky bit came when [Tysonpower] realized that the rendezvous would happen when the ISS was in a good position relative to his home in Cologne, which prompted him to set up his gear for a listening session. His AirSpy Mini SDR was connected to a home-brew quadrifilar helical (QFH) “eggbeater” antenna on his roof. What’s nice about this antenna is that it’s fixed rather than tracking, making it easy to get on the air with quickly. After digging around the aviation bands at about 121 MHz for a bit, [Tysonpower] managed to capture a few seconds of a conversation between [Ovchinin] and Moscow Flight Control Center. The commander reported his position and speed relative to the ISS a few minutes before docking. The conversation starts at about 1:12 in the video below.
We think it’s just cool that you can listen in on the conversations going on upstairs with a total of less than $50 worth of gear. Actually talking to the hams aboard the ISS is another matter, but not a lot more involved really.
9 thoughts on “Eavesdropping On Cosmonauts With An SDR”
Is it just me, or is he several kHz off from center?
The ISS is travelling at ~7.66 km/s (~4.75 miles/second), could it be Doppler shift ?
Jup it’s due to Doppler.
It’s 121.750mhz +/- 3khz of Doppler Shift.
Wouldn’t it have to be travelling towards or away from the earth for it to be a Doppler Shift?
If the receiver were at the center of the Earth, yes. Since they’re usually on the surface, traveling around a circular orbit is enough. Anything that changes the distance between the transmitter and receiver produces Doppler shift.
I’d like to shop where he shops. I’d like to know where I can buy a laptop, SDR dongle, cabling to reach the roof and materials to build an egg beater. All for less than $50. Great deal.
Basically the same equipment I use to record NOAA-POES weather satellites — and I think the most expensive thing I bought was the low-noise amplifier for 137MHz (which you can do without if you a have a really good antenna and cable). Easily doable for $50-$100, depending on what you can scrounge or re-purpose.
Well my gear is a bit more expensive then 50$ (i didn’t wrote that anywhere did i? The Post here is not from me), but it is doeable.
20$ for an RTL-SDR, 20$ for DIY QFH Antenna or similar and 10$ for cabels etc.
Anyone has a PC or Smartphone and Software is free.
Please – $50 worth of gear he didn’t already have.
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