Abstract: An active noise cancellation system that reduces, at a listening position, power of a noise signal radiated from a noise source to the listening position. The system includes an adaptive filter, at least one acoustic actuator and a signal processing device. The adaptive filter receives a reference signal representing the noise signal, and provides a compensation signal. The at least one acoustic actuator radiates the compensation signal to the listening position. The signal processing device evaluates and assesses the stability of the adaptive filter.

Abstract: A mobile device (110), e.g. a token, holds a current key and one or more previous (expired) keys in memory (130). If the token needs to communicate with another device (144), e.g. with a reader, and the reader does not have the current key but has a previous key, the token encrypts the current key with the previous key and sends the ciphertext to the reader, which decrypts the current key. The token use different cryptographic material for communication with respective different facilities. Rather than requesting the reader to identify the facility, the token assumes that the facility is the same as in the most recent successful authentication. If the authentication fails, only then the token requests the reader to identify the facility. Authentication time and electric power are saved if the facility is the same. Other embodiments are also provided.

Abstract: An electronic door lock (“EDL”) is adapted to interact with an electronic key unit having a key antenna and a transmitter configured to transmit a radio frequency (“RF”) signal over the key antenna, the RF signal containing an identification (“ID”) code identifying the electronic key unit. The EDL can include a first antenna adapted to form a first directional radiation beam to receive the RF signal from the key unit, a second antenna adapted to form a second directional radiation beam to receive the RF signal from the key unit, and a processing component adapted to use RF signals received by one or both of the first and second antenna to determine whether the presence of an acceptable ID code is detected on the key. The EDL can determine the location of the key, and whether the key is inside or outside of the room.

Abstract: Improved access control systems (100) are provided which control access to resources. Among other things, improved techniques are provided for checking for access control data integrity. These techniques are not limited to access control data or systems.

Abstract: A mobile device (110), e.g. a token, holds a current key and one or more previous (expired) keys in memory (130). If the token needs to communicate with another device (144), e.g. with a reader, and the reader does not have the current key but has a previous key, the token encrypts the current key with the previous key and sends the ciphertext to the reader, which decrypts the current key. The token use different cryptographic material for communication with respective different facilities. Rather than requesting the reader to identify the facility, the token assumes that the facility is the same as in the most recent successful authentication. If the authentication fails, only then the token requests the reader to identify the facility. Authentication time and electric power are saved if the facility is the same. Other embodiments are also provided.

Abstract: A radio device and a method to operate a non-heterodyne receiver are provided. The radio device is configured to receive a signal waveform and to provide a wake-up signal to a second communication circuit when the signal waveform is a valid communication request; wherein the second communication circuit switches from a power saving state to an operating state upon receiving the wake-up signal from the non-heterodyne receiver. The non-heterodyne receiver further including an Electromagnetic interference (EMI) rejection circuit, including a narrow band filter and a broadband filter to reject an EMI signal. A filter circuit for a narrow passband circuit is also provided. The filter including a buffer circuit; a crystal oscillator coupled to the output of the buffer circuit; and an inverting amplifier coupled in parallel to the crystal oscillator.

Abstract: Adaptive noise control for reducing power of an acoustic noise signal radiated from a noise source to a listening position comprises providing an electrical reference signal correlated with the acoustic noise signal; filtering the electrical reference signal with an adaptive filter to provide an electrical output signal; multiplying the electrical output signal of the adaptive filter by a gain factor to provide a first electrical compensation signal; filtering and multiplying the electrical output signal of the adaptive filter by the inverse of the gain factor to provide a second electrical compensation signal, the second gain factor being equal to 1 subtracted by the first gain factor; radiating the first electrical compensation signal to the listening position with an acoustic transducer; sensing a residual electrical error signal at the listening position; adding the second electrical compensation signal to the electrical error signal to provide a compensated error signal; and adapting filter coefficients

Abstract: A system for actively reducing noise at a listening point, includes an earphone housing, a transmitting transducer, a receiving transducer and a controller. The transmitting transducer converts a first electric signal into a first acoustic signal, and radiates the first acoustic signal along a first acoustic path having a first transfer characteristic and along a second acoustic path having a second transfer characteristic. The receiving transducer converts the first acoustic signal and ambient noise into a second electrical signal. The controller compensates for the ambient noise by providing a noise reducing electrical signal to the transmitting transducer. The noise reducing electrical signal is derived from a filtered electrical signal that is provided by filtering the second electrical signal with a third transfer characteristic. The second and the third transfer characteristics together model the first transfer characteristic.

Abstract: An active noise cancellation system includes an adaptive filter, a signal source, an acoustic actuator, a microphone, a secondary path and an estimation unit. The adaptive filter receives a reference signal representing noise, and provides a compensation signal in response to the received reference signal. The signal source provides a measurement signal. The acoustic actuator radiates the compensation signal and the measurement signal to the listening position. The microphone receives a first signal that is a superposition of the radiated compensation signal, the radiated measurement signal, and the noise signal at the listening position, and provides a microphone signal in response to the received first signal. The secondary path includes a secondary path system that represents a signal transmission path between an output of the adaptive filter and an output of the microphone.

Abstract: An active noise cancellation system that reduces, at a listening position, power of a noise signal radiated from a noise source to the listening position. The system includes an adaptive filter, at least one acoustic actuator and a signal processing device. The adaptive filter receives a reference signal representing the noise signal, and provides a compensation signal. The at least one acoustic actuator radiates the compensation signal to the listening position. The signal processing device evaluates and assesses the stability of the adaptive filter.

Abstract: A client node is communicatively coupled to a gateway node via a TCP/IP network. One or more constrained devices that include a wireless receiver/transmitter circuit communicate with the gateway node via a wireless network. The gateway node includes a web server that provides a dynamic web page accessible by the client node that has a list of the one or more active constrained devices on the wireless network. Each device entry in the list includes a URL that acts as an entry point for the client node to communicate with a web server in a corresponding constrained device. The gateway node automatically discovers a new device on the wireless network and populates the list of the one or more active constrained devices with the newly present constrained device. The new constrained device may be detected based on a periodic message sent by the constrained device indicating the constrained device has turned on its receiver/transmitter circuit for a period of time.