Victor X-Ray Juliet Info
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Designer, maker and licensed radio amateur operating under the callsign M7VXJ. This site documents my ongoing experimentation with radio telegraphy, satellite reception, electronic engineering and related projects.

I also create computer generated animation as silico.studio and design bespoke 3D printed products, which are avalable for purchase from physis.shop.
Radios   
   Yaseu FT-857     Yaesu FT-818      Yaseu FT-4X        LilyGo T-Echo     RTL-SDR       Hack-RF        T1000-E  
Antennas                      Diamond VX30N [2m,70cm]                        DIY V-Dipole [137 MHz]                        Parabolic [1.7GHz]                        EFHW [7, 14 MHz]                    
           
15th November 2025
QPSK Constellation Plot
Artwork

    Quadrature Phase Shift Keying (QPSK) is a digital modulation method that encodes two bits of information by shifting the carrier between four distinct phase angles.

    QPSK efficiently encodes information into analog signals and is used in many applications. I first encountered it when decoding weather imagery from the Russian Meteor-M satellites; their “LRPT” image downlink uses QPSK modulation.

    As part of an ongoing video project and as a way to better understand how it works, I made this animation that visualizes a QPSK constellation plot, showing how symbols cluster into four phase states and how noise/spread affects demodulation.