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Re:Designing a Home Radio Telescope for 21 Cm Emission by radioguy22 on Monday November 04, 2024 @02:59PM (#42045454)
Start detecting signal reflections from airplanes.

With multiple synchronized receivers you can build a passive radar.

Single reflections can easily be spotted by just staring at the spectrum (Doppler).

Re:Designing a Home Radio Telescope for 21 Cm Emission by Enginerrrd on Monday November 04, 2024 @03:28PM (#42045699)
I'm super into this idea as a project, can you point me to any design or signal processing info?
Re:Designing a Home Radio Telescope for 21 Cm Emission by kortilla on Monday November 04, 2024 @03:35PM (#42045755)
A lot of passive radar stuff is ends up export controlled so open source is sparse here
Re:Designing a Home Radio Telescope for 21 Cm Emission by schnitzelbot on Tuesday November 05, 2024 @12:50AM (#42048918)
There are a lot of open source projects. And technology (algorithms and receivers) wise it isn't too complicated nor a secret. That stuff is almost 100 years old.

An easy start is always looking at VHF reflection of strong transmitters that are not creating a lot of noise (like FM stations). ILS or VORs stations are classics.

There are also a lot of meteor and space radars ( https://en.wikipedia.org/wiki/GRAVES_(system) ). Universities are super happy in publishing very very detailed (https://www.iap-kborn.de/en/research/department-radar-remote...) specs of their sky radars. And frequencies are well known for ages.

Re:Designing a Home Radio Telescope for 21 Cm Emission by scottapotamas on Monday November 04, 2024 @09:40PM (#42048134)
Have a look at this (and other repos/website) https://github.com/30hours/blah2
Re:Designing a Home Radio Telescope for 21 Cm Emission by transpute on Monday November 04, 2024 @10:09PM (#42048254)
For room-scale passive radar, search HN for IEEE 802.11bf and WiFi 7 Sensing.

https://github.com/Marsrocky/Awesome-WiFi-CSI-Sensing