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Lissajous Figures

I covered this before but JIC (just in case). Inputting signals to your DSO and invoking X versus Y functionality you can derive a relationship between signals such as Phase difference. A 90-degree phase difference is critical in the SDR world. 

The 1st line and middle set of three figures is where two signal inputs are shown for a square wave. The last figure in this middle set is for a 90-degree phase shift, our tilted square shown yesterday. The last figure in the first set of three is the circle which as we saw yesterday from the I and Q output of the sound card was not a perfect circle indicating not 90 degrees.


These graphs have a technical name called Lissajous Figures (some suggest pronounced Leesa Juice) and are old school and approaching over 200 years old (circa 1815).  

For those who served in the US Navy and had to do navigation, Nathan Bowditch is a name that invented those figures for navigation. I had to take a course in Navigation while a Midshipmen. I was supposed to be in the Pacific off the coast of Oahu, but my plot was in the Gobi Desert. Another reason why I didn't serve aboard ship and in the Seabees!

Them that know can make it go

73's
Pete N6QW


Note: Pi/2 represents a 90-degree Phase shift. Ask Microshaft Co-Pilot.



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