Frame Check Sequence (FCS), sometimes also called Cyclic Redundancy Check, in High-level Data Link Control (HDLC) frame used for the Point-to-Point Protocol (PPP) — a practical approach for the programmer.
The file transfer protocol uses two ports and can be used in active or passive mode. The difference of those two modes is shown.
The electromagnetic spectrum from the ultra long waves to the microwaves with the names, frequencies and bands.
Some calculators that help in determining the parameters necessary to access a telecommunications satellite.
More contributions on this topic are still on my old site. What's missing here will be transferred and adjusted in due time.