SETI / Breakthrough Listen REU 2022 materials

This repository contains miscellanous materials used with the SETI and Breakthrough Listen Research Experience for Undergraduates summer programs. The material was elaborated in the context of the collaboration between GNU Radio and SETI Institute.

Outline

The material is organized in the following folders:

broadcast-fm shows how to FM-demodulate a broadcast FM station received with an RTL-SDR. The goal is to show the additional subcarriers which are "hidden" in the signal besides the main (mono A+B) audio: these are 19 kHz pilot tone, stereo (A-B) audio, and RDS.
Hydrogen_line is an activity done in person at the Allen Telescope Array. Different parts of the galactic plane were observed, and the spectrum at 1.42 GHz was measured. From the measurements of the Doppler of the HI line, the rotation and structure of the Milky Way was discussed.
interferometry contains a simulation of a two-antenna interferometer with an FX correlator. It shows concepts such as lag domain and frequency domain, fringe rotation and fring stopping. There is also a demo with the Allen Telescope Array using the same kind of correlator.
polyphase shows how to implement a polyphase filterbank and write GUPPI raw files using gr-guppi. It also shows how to generate a CW signal that drifts in frequency. This can signal then be detected with turbo_seti if the GUPPI raw file is processed with rawspec.
python-blocks shows how to program Embedded Python Blocks. A signal detection block is implemented as an example. This detects signals on the spectrum by using a median to estimate the noise floor. Messages are used to control the frequency of a Frequency Xlating FIR Filter and tune a receiver to the strongest signal detected.
slides contains some introductory slides describing GNU Radio.
spectral-analysis shows how to construct a spectrometer with the FFT and Integrator blocks. It includes a simulation of narrowband and wideband signals and demos using Voyager 1 and the HI spectral line.
vor-freq-measurement shows how the measure precisely the carrier frequency of a VOR station received with an RTL-SDR, by taking phase measurements with a PLL. It also shows how to process the VOR bearing information by demodulating the AM information on the carrier and the FM information on the sidebands and comparing the phases of the resulting 30 Hz sinewaves.