FI (Note)/(Index) list

Descriptions for H04K and notes/indexes are displayed on this screen.

H04K SECRET COMMUNICATION; JAMMING OF COMMUNICATION

Note(s)
In this subclass, the following expression is used with the meaning indicated:
    "secret communication" includes secret line and radiation transmission systems, i.e. those in which apparatus at the transmitting station modifies the signal in such a way that the information cannot be intelligibly received without corresponding modifying apparatus at the receiving station.