Final answer:
The term for an encrypted or scrambled signal is modulation, which can be achieved through changing a wave's amplitude, frequency, or phase. Deciphering such signals requires understanding the specific modulation technique. Recognizing messages from an alien species might be challenging if they use unfamiliar encoding methods.
Step-by-step explanation:
The term used to describe an encrypted, encoded, scrambled, or other nonstandard signal is modulation. Modulation involves varying a carrier wave's properties—such as its amplitude, frequency, or phase—to encode information. When it comes to deciphering the message encoded in the signal, sophisticated equipment and knowledge of the modulation technique used are required. For instance, Amplitude Modulation (AM) varies the wave's amplitude, Frequency Modulation (FM) changes its frequency, and phase modulation alters its phase.
Regarding the potential of recognizing a message from an alien species, it presents a significant challenge. If such a message does not conform to the signal encoding methods we understand or occurs in an unexpected format, it might be difficult or even impossible to recognize and interpret without a mutual frame of reference.