Passive communication device and passive access control system
First Claim
1. A passive communication device for use in a communication system also having a base station, the communication device comprising an internal power source, receiver means for receiving signals transmitted from the base station, and processing means selectively responsive to an interrogation signal received from the base station by said receiver means to generate a data signal for transmission to the base station,wherein said receiver means comprises a first receiver element and a second receiver element, said first receiver element having a lower power consumption when energised than said second receiver element does when energised,said communication device having a standby state in which said internal power source energises said first receiver element so as to detect the presence of a received signal, and in which said second receiver element and said processing means are de-energised,said first receiver element being responsive to detection of a received signal to trigger a state of operation of said communication device in which said internal power source energises said second receiver element,said second receiver element, when energised, being selectively responsive to a characteristic of the signal received to enable said internal power source to energise said processing means and to trigger an active state of operation in which said processing means is actuated,and said processing means comprising demodulator means responsive to a modulation of the received signal when said demodulator means is actuated.
18 Assignments
0 Petitions
Accused Products
Abstract
A communication device comprising an internal power source, first and second receiver elements for receiving signals transmitted from the base station, and a processor selectively responsive to a modulation of the received signal to generate a data signal for transmission to the base station. The first receiver element has lower power consumption than the second receiver element does when energised. At least during a standby state of the device, the first receiver element is activated to detect the presence of a received signal, the second receiver element and the processing means being de-energised. The first receiver element is responsive to detection of a received signal to trigger an active state in which the second receiver element is activated to respond selectively to the frequency of the signal received to actuate the processor. The invention is applicable to vehicle access control systems, and tire pressure monitoring systems.
17 Citations
12 Claims
-
1. A passive communication device for use in a communication system also having a base station, the communication device comprising an internal power source, receiver means for receiving signals transmitted from the base station, and processing means selectively responsive to an interrogation signal received from the base station by said receiver means to generate a data signal for transmission to the base station,
wherein said receiver means comprises a first receiver element and a second receiver element, said first receiver element having a lower power consumption when energised than said second receiver element does when energised, said communication device having a standby state in which said internal power source energises said first receiver element so as to detect the presence of a received signal, and in which said second receiver element and said processing means are de-energised, said first receiver element being responsive to detection of a received signal to trigger a state of operation of said communication device in which said internal power source energises said second receiver element, said second receiver element, when energised, being selectively responsive to a characteristic of the signal received to enable said internal power source to energise said processing means and to trigger an active state of operation in which said processing means is actuated, and said processing means comprising demodulator means responsive to a modulation of the received signal when said demodulator means is actuated.
-
8. A passive communication device for use in a communication system also having a base station, the communication device comprising an internal power source, receiver means for receiving signals transmitted from the base station, and processing means selectively responsive to an interrogation signal received from the base station by said receiver means to generate a data signal for transmission to the base station,
wherein said receiver means comprises a first receiver element and a second receiver element, said first receiver element having a lower power consumption when energised than said second receiver element does when energised, said communication device having a standby state in which said internal power source energises said first receiver element so as to detect the presence of a received signal, and in which said second receiver element and said processing means are de-energised, said first receiver element being responsive to detection of a received signal to trigger a state of operation of said communication device in which said internal power source energises said second receiver element, said second receiver element, when energised, being selectively responsive to a characteristic of the signal received to enable said internal power source to energise said processing means and to trigger an active state of operation in which said processing means is actuated, and said receiver means comprises reset means for triggering said standby state in the absence of a signal received by said first receiver element and of the transmission of a signal by the communication device.
-
11. A passive communication device for use in a communication system also having a base station, the communication device comprising an internal power source, receiver means for receiving signals transmitted from the base station, and processing means selectively responsive to an interrogation signal received from the base station by said receiver means to generate a data signal for transmission to the base station,
wherein said receiver means comprises a first receiver element and a second receiver element, said first receiver element having a lower power consumption when energised than said second receiver element does when energised, said communication device having a standby state in which said internal power source energises said first receiver element so as to detect the presence of a received signal, and in which said second receiver element and said processing means are de-energised, said first receiver element being responsive to detection of a received signal to trigger a state of operation of said communication device in which said internal power source energises said second receiver element, said second receiver element, when energised, being selectively responsive to a characteristic of the signal received to enable said internal power source to energise said processing means and to trigger an active state of operation in which said processing means is actuated, and said receiver means comprising antenna means for receiving transmitted signals and switch means for connecting said antenna means with said first receiver element, said switch means being responsive to detection by said first receiver element of a signal received by said antenna means to trigger connection of said antenna means with said second receiver element.
Specification