multi Frequency Full Duplex Transmissions Multiplexing alternating current termination communication transmission

 https://www.nature.com/articles/srep38181

Full-duplex bidirectional data transmission link using twisted lights multiplexing over 1.1-km orbital angular momentum fiber | Scientific Reports

https://www.openworldlearning.org/revolutionizing-data-transmission-an-overview-of-multiplexing-and-its-applications/

LM565 IC frequency multiplier 7490 counter

https://www.eeeguide.com/frequency-multiplier-using-pll-565/

https://en.wikipedia.org/wiki/Multiplexing 

linear multiplier Frequency multiplication effect

www.crystek.com%2Fdocuments%2Fappnotes%2Ffrequency_multiplication_techniques.pdf