The following video shows a breadboarded Arduino automatically tuning a amateur radio's transmitting and receiving frequencies so as to allow two-way communications through a satellite. It also shows the accuracy of the doppler tuning while tracking a single satellite's tone through its pass: …

Amateur satellite tracking and tuning

system April 22, 2010, 7:47am 10

BTW, you can see my electronics tinkerings at my WEB:

73 JOSE EB5AGV