Encoding and Decoding the Arecibo 1974 SETI Message

The reason for this article is, in fact, sad. The world-famous radio telescope of the Arecibo Observatory in Puerto Rico has collapsed and is beyond repair. For many years it was the largest radio telescope in the world (diameter 304 m, frequency range up to 10 GHz), with the help of which many discoveries were made. On this Wikipedia image it is still in working condition:

Source: Wikipedia