Parabolic dish focal ratios & spillover angles
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From Alex Pettit 2-3/12/2025: Its related to the Feed Beam Pattern and the Shape ( f/D Depth ) of the dish. “All” f/D 0.35 dishes perform similarly regardless of diameter…
Applying the Nyquist theorem to radio astronomy
Great question — this is a very common confusion when first applying the Nyquist theorem to radio astronomy. You do not need a 2.8 GHz sample rate to observe the…
Nyquist theorem explanation
Here is the Nyquist explanation rewritten using pure ASCII diagrams (no Unicode). Nyquist Theorem (ASCII Version) The Nyquist theorem says: This minimum rate is the Nyquist rate. 1. Sine wave…
Tohtsu CX-520D coaxial relay product info from DX Shop 3 December 2025
https://www.astronomy.me.uk/wp-content/uploads/2025/12/Tohtsu-CX-520D-product-info-from-DX-Shop-031225-reduced.pdf
I have installed usbrelay softwate on Ubuntu for my 4 relay control board (which works on Windows). Running the command usbrelay detects device but can’t open it.
I have installed usbrelay softwate on Ubuntu for my 4 relay control board (which works on Windows). Running the command usbrelay detects device but can’t open it. If usbrelay sees…
Batch file used at LRO to process data Nov 2025
REM Identify data folder structure. REM The folder structure should be LRO folder with sub-folder called data. Save .txt data files in data and any .ezb and .npz data files…
British Astronomical Association Hydrogen Line Sub-group meeting 1/12/2025
https://files.ad.thornett.net/astronet/BAA_H-Line_Meeting_011225.mp4
Is it beneficial to have full wavelength sized antennas rather than half wavelength?
In most practical radio-astronomy and communication setups, a full-wavelength antenna is not inherently “better” than a half-wavelength one—they simply behave differently, and the choice depends on what pattern, impedance, and…
How does amplification on Nooelec SAWBird H1 vary with voltage on power supply input?
Short answer: the SAWbird H1’s gain is essentially fixed by its RF amplifier bias network and SAW filter — within the manufacturer’s recommended supply window (≈3.3–5.5 V) you should see…
Comparing RTL-SDR v3 and v4 software defined radios
Here’s what’s inside — i.e. the chips used: In short: R820T2 tuner + RTL2832U demodulator/ADC. Since you’re already familiar with SDR and radio-astronomy, here’s a summary of the key components…