Remote-control access control device and method for operating the same

A remote-control access control device, comprising:

• tripping means;
• an unlocking unit;
• a stationary transmitter and receiver unit responding to actuation of said tripping means for transmitting a question code signal, receiving an answer code signal, and furnishing an unlocking signal to said unlocking unit if the answer code signal matches a command code signal;
• a portable transponder having a receiver receiving the question code signal and a transmitter transmitting the answer code signal;
• and
• means for modifying a signal parameter when the answer code signal is transmitted if an information content of the question code signal indicates an emergency operation state.

remote-control access control device, comprising:

• tripping means;
• an unlocking unit;
• a stationary transmitter and receiver unit responding to actuation of said tripping means for transmitting a question code signal, receiving an answer code signal, and furnishing an unlocking signal to said unlocking unit if the answer code signal matches a command code signal;
• and
• a portable transponder having a transmitter transmitting the answer code signal and a receiver receiving the question code signal;
• said transmitter and receiver unit having both a transmission channel for receiving signals of low field intensity and a transmission channel for receiving signals of high field intensity.

A method for operating a remote-access control device, which comprises:

• transmitting a question code signal from a stationary transmitter and receiver unit upon actuation of tripping means;
• receiving the question code signal at a transponder and transmitting an answer code signal from the transponder to the transmitter and receiver unit;
• comparing the answer code signal with a command code signal in the transmitter and receiver unit, and sending an unlocking signal to an unlocking unit if the answer code signal and the command code signal match;
• bringing the transponder to the vicinity of the transmitter and receiver unit and modifying a signal parameter if no unlocking signal has been tripped after the initial actuation of the tripping means;
• and actuating the tripping means once again for transmitting the question code signal.