The Hydrogen Line is created by a change in start of neutral hydrogen atoms. It is defined by an emission of wavelngth 21.106 cm, in a vacuum. This emission has an associated wavelength of 1420.405751 MHz.
One basis of this project is the use of Welch's method. Welch's method estimates the power spectral density of a signal by dividing it into overlapping segments, computing a modified periodogram for each, and averaging the results to reduce variance. The benefit of using this field is that Welch's method reduces the variance of spectral estimates compared to a single FFT by averaging multiple overlapping windowed segments, resulting in a smoother and more reliable power spectrum. In "dynamic averaging"x, this process plays a key role by allowing the averaging of multiple power spectral density (PSD) estimates—each from overlapping, windowed segments of a signal—so that short-term fluctuations are smoothed out, enhancing the stability and clarity of frequency content over time.
In this project, we use a Nooelec Satellite Mesh (1.4 GHz center frequency), fed into a Nooelec Sawbird H1+, containing a RF amplifier / band-pass filter / RF amplifier combo. In third, it is fed into an RTL-SDR V4, a radio signal processor.