Data transmission for remote-controlled security system

Abstract

A remote-controlled apparatus improves the reliability of a vehicle security system. Each time the transmitting unit transmits data, a first code updating section changes a variable code storage in a memory in the transmitting unit by predetermined shift processing to form a new variable code, and replaces the preceding variable code with the new variable code. An ID code setting section sets an ID code formed of the variable code and a fixed code. Predetermined data including the ID code and command signals is transmitted. When the receiving unit receives the predetermined data, the fixed code and the variable code in the received ID code are compared with a fixed code and a variable code stored in the receiving unit. If it is thereby determined that the fixed codes and predetermined portions of the variable codes coincide with each other, a predetermined security operation is started or stopped according to the content (command signals) of the received data, and a code updating section in the receiving unit changes the received variable code by predetermined shift processing to form a new variable code, and replaces the preceding stored variable code in the receiving unit with the new code.