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My own attempt at completing homework exercises from BAA GNU Radio Group Meeting 29/11/2025: Create an electronic keyboard which plays multiple music chords, and create an AM radio player
My GNU Radio Companion GRC file that plays multiple music chords: https://www.astronomy.me.uk/wp-content/uploads/2025/12/BAA-GNU-Radio-Meeting-Exercise-Chord-Selector-201225_GRC.zip Video showing the above GRC in action: My AM radio player (users can select from recorded IQ file…
Mathematical relationship between chords in music (for BAA GNU Radio Meeting homework)
To change a C major chord into a D major chord, you need to multiply the frequency of each note by (2^{2/12}) (the twelfth root of two raised to the…
Physicists Finally Confirm the Existence of “Time Mirrors”
Summary of research article (Moussa et al., 2023): The following was published on December 26, 2025 in https://dailygalaxy.com/2025/12/physicists-prove-time-mirrors-real-with-electromagnetic-flip/ Physicists have experimentally reversed electromagnetic waves in time. The process, known as…
How to use directional coupler to provide reference signal in Easy Radio Astronomy software (suggestions by ChatGPT 27/12/2025)
The following are suggestions from ChatGPT (effectiveness not verified, 27/12/2025): Easy Radio Astronomy (ezRA) expects a stable reference channel so it can compare amplitude and/or phase changes against the sky…
Using directional couplers to provide reference signals for hydrogen line radio astronomy
Andy, A directional coupler is a device which allows RF to pass along one path in either direction with very low insertion loss while tapping off a reference signal at…
Screen shielding fabrication to reduce RFI:
On SARA Mailing list from Alex Pettit 27/12/2025 re screen shielding fabrication to reduce RFI:
RF Reference Signals using very low insertion loss 20+ dB isolation directional couplers fed with an active noise source of known noise power and spectral characteristics.
From Robert Meade, SARA mailing list 24/12/2025: Rather than using Dicke switching of the RF path between the antenna and a resistor as a noise source with PIN diodes, physical…
Processing LRO-H1 (Ptarmigan Array Radio Telescope) Data 25/3/2025-25/12/2025 – Milky Way Map 25/3/2025-25/12/2025 using one month drift scans at each elevation
Hi All I hope you have enjoyed Christmas Day – I have just processed the first part of my data set using one month per drift scan elevation = the…
Designing & Constructing a Cantenna (Circular Waveguide Antenna / Tuned Cylindrical Waveguide) for hydrogen line radio astronomy (1420 MHz)
Here is what you need to build your own Cantenna: Doing the math:Use an online calculator, such as the one at https://www.jefatech.com/products/cnfbst?keyword=cantenna, or https://www.changpuak.ch/electronics/cantenna.php, https://www.wikarekare.org/Antenna/WaveguideCan.html to check can size and…