It may not be the radio station with all the hits and the best afternoon drive show, but 1420.4058 MHz is the most popular frequency in the universe. That’s the electromagnetic spectral line of hydrogen, and it’s the always on the air. 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, H-line emissions are abundant, and their distribution can tell us a lot about the structure of galaxies. The 21-cm emission line is so characteristic and …read more http://pje.fyi/PcRkYx