A Nooelec Sawbird+ H1 acts as preamp and filter for the 1420-MHz hydrogen line signal, which feeds into an RTL-SDR dongle. Careful attention is paid to proper grounding and shielding to keep the ...

But studying the H-line is a non-trivial task unless you know how to cascade low-noise amplifiers and filters to use an SDR for radio astronomy. Because the universe is mostly made of hydrogen ...