Abstract: A differential mixer and a method which can reduce a leak component of a local oscillation differential signal are provided. A differential mixer includes a mixer core unit to which a high frequency signal and a local oscillation differential signal are inputted and which outputs an intermediate frequency differential signal, a common feedback unit which applies a bias voltage to a signal electrically coupled to the high frequency signal and to which a common voltage is fed back from the intermediate frequency differential signal, and a bias unit that applies a reference voltage to the common feedback unit. The common feedback unit generates the bias voltage based on the reference voltage. The bias unit controls the reference voltage so that a leak component of the local oscillation differential signal is a predetermined value or less at an output end of the intermediate frequency differential signal.

Abstract: To provide a variable gain amplifier capable of correcting a DC offset voltage through simpler control even when a gain thereof is changed. A differential output type variable gain amplifier is equipped with a first voltage correction unit coupled to a preceding stage of a variable gain amplifier circuit and for outputting a first correction voltage to correct a potential difference generated between a first conductor provided with a first input resistor and a second conductor provided with a second input resistor, and a second voltage correction unit coupled to a subsequent stage of the variable gain amplifier circuit and for correcting a differential output. A control unit is configured to control the first correction voltage and a correction amount of a potential difference by the second voltage correction unit and thereby attenuate a DC offset voltage included in the differential output.

Abstract: A secure communication system is provided, in which a common cryptographic key is generated using the biological information simultaneously acquirable by multiple communication devices. The communication system includes multiple separated communication devices. The communication device generates the same common key based on the feature element of simultaneously acquirable biological information, and performs encryption and decryption using the common key. The communication device includes a biological information acquiring unit to acquire the feature element of the biological information; a common key generation unit to generate the common key; an encryption/decryption unit to encrypt transmit information and to decrypt receive information with the common key; and a communication unit to receive the transmit information and to transmit the receive information.

Abstract: A differential mixer and a method which can reduce a leak component of a local oscillation differential signal are provided. A differential mixer includes a mixer core unit to which a high frequency signal and a local oscillation differential signal are inputted and which outputs an intermediate frequency differential signal, a common feedback unit which applies a bias voltage to a signal electrically coupled to the high frequency signal and to which a common voltage is fed back from the intermediate frequency differential signal, and a bias unit that applies a reference voltage to the common feedback unit. The common feedback unit generates the bias voltage based on the reference voltage. The bias unit controls the reference voltage so that a leak component of the local oscillation differential signal is a predetermined value or less at an output end of the intermediate frequency differential signal.

Abstract: To provide a variable gain amplifier capable of correcting a DC offset voltage through simpler control even when a gain thereof is changed. A differential output type variable gain amplifier is equipped with a first voltage correction unit coupled to a preceding stage of a variable gain amplifier circuit and for outputting a first correction voltage to correct a potential difference generated between a first conductor provided with a first input resistor and a second conductor provided with a second input resistor, and a second voltage correction unit coupled to a subsequent stage of the variable gain amplifier circuit and for correcting a differential output. A control unit is configured to control the first correction voltage and a correction amount of a potential difference by the second voltage correction unit and thereby attenuate a DC offset voltage included in the differential output.

Abstract: A protection support system allows for protecting efficiently a target such as an elderly person who is wandering around. In the protection support system, a protection terminal includes an identification information receiving unit that receives identification information from a transmitter and a discovery information transmitting unit that transmits discovery information including the identification information that has been received. The protection support server includes a discovery information receiving unit that receives the discovery information, a request-side information storage unit that stores request-side information in which information on the person to be protected is associated with the identification information, a disclosure range determination unit that determines a disclosure range of the request-side information, and a protection request demand transmitting unit that transmits a protection request demand including the request-side information within the disclosure range.

Abstract: A scanner system includes a pen-shaped scanner that scans a character strings that is one part of a sentence described in a paper book and generates and transmits sentence image data on the basis of the scanned character string, a storage unit that stores therein book image data that is higher in image quality than the sentence image data and is obtained by electronically imaging the sentence described in the paper book, and a matching unit that compares the book image data with the sentence image data that the pen-shaped scanner has transmitted and extracts partial image data that has been decide to match the sentence image data from the book image data.

Abstract: A radio apparatus that allows a user to check a state of a power supply is provided. A radio transmitting apparatus 10 includes a power supply voltage measurement unit 11 that measures a power supply voltage, a transmission power determination unit 12 that determines a transmission power based on the power supply voltage that has been measured, and a radio transmitting unit 13 that transmits by radio an advertisement packet including transmission power information indicating the transmission power that has been determined at the transmission power that has been determined. A radio receiving apparatus 20 includes a radio receiving unit 23 that receives the advertisement packet and a power supply state detection unit 21 that detects the state of the power supply of the radio transmitting apparatus 10 based on the transmission power information included in the advertisement packet.

Abstract: A scanner system includes a pen-shaped scanner that scans a character strings that is one part of a sentence described in a paper book and generates and transmits sentence image data on the basis of the scanned character string, a storage unit that stores therein book image data that is higher in image quality than the sentence image data and is obtained by electronically imaging the sentence described in the paper book, and a matching unit that compares the book image data with the sentence image data that the pen-shaped scanner has transmitted and extracts partial image data that has been decide to match the sentence image data from the book image data.

Abstract: There is to provide a communication device capable of reducing the power consumption. The communication device includes a battery and a transmission circuit for transmitting a signal of a desired transmission frequency upon receipt of a power supply from the battery. The transmission circuit includes a first oscillator for oscillating a signal, an amplifier for amplifying the signal oscillated by the first oscillator, and a filter circuit for eliminating a harmonic component included in the signal output from the amplifier. The filter circuit includes an extracting unit for extracting a frequency signal of n (n?2) times frequencies of the transmission frequency from the signal output from the amplifier and a recovery unit for recovering the battery with DC component of the extracted n times frequency signal.

Abstract: A communication device includes a communication circuit capable of switching a reception or a transmission of a desired frequency signal through an antenna.

Abstract: A protection support system allows for protecting efficiently a target such as an elderly person who is wandering around. In the protection support system, a protection terminal includes an identification information receiving unit that receives identification information from a transmitter and a discovery information transmitting unit that transmits discovery information including the identification information that has been received. The protection support server includes a discovery information receiving unit that receives the discovery information, a request-side information storage unit that stores request-side information in which information on the person to be protected is associated with the identification information, a disclosure range determination unit that determines a disclosure range of the request-side information, and a protection request demand transmitting unit that transmits a protection request demand including the request-side information within the disclosure range.

Abstract: A radio apparatus that allows a user to check a state of a power supply is provided. A radio transmitting apparatus 10 includes a power supply voltage measurement unit 11 that measures a power supply voltage, a transmission power determination unit 12 that determines a transmission power based on the power supply voltage that has been measured, and a radio transmitting unit 13 that transmits by radio an advertisement packet including transmission power information indicating the transmission power that has been determined at the transmission power that has been determined. A radio receiving apparatus 20 includes a radio receiving unit 23 that receives the advertisement packet and a power supply state detection unit 21 that detects the state of the power supply of the radio transmitting apparatus 10 based on the transmission power information included in the advertisement packet.

Abstract: There is to provide a communication device capable of reducing the power consumption. The communication device includes a battery and a transmission circuit for transmitting a signal of a desired transmission frequency upon receipt of a power supply from the battery. The transmission circuit includes a first oscillator for oscillating a signal, an amplifier for amplifying the signal oscillated by the first oscillator, and a filter circuit for eliminating a harmonic component included in the signal output from the amplifier. The filter circuit includes an extracting unit for extracting a frequency signal of n (n?2) times frequencies of the transmission frequency from the signal output from the amplifier and a recovery unit for recovering the battery with DC component of the extracted n times frequency signal.

Abstract: A communication device includes a communication circuit capable of switching a reception or a transmission of a desired frequency signal through an antenna.

Abstract: There is a need to reduce secondary intermodulation distortion that may occur in a reception circuit of a high-frequency signal processor and a wireless communication system having the same. In test mode, for example, a test signal generating circuit TSGEN generates a test signal RFtst at f_tx±0.5 MHz. The test signal RFtst is input to a mixer circuit MIXrx_I (MIXrx_Q). A correction circuit block CALBK detects an IM2 component resulting from the MIXrx_I (MIXrx_Q). The CALBK varies a differential balance for the MIXrx_I (MIXrx_Q) and concurrently monitors a phase for the IM2 component resulting from MIXrx_I (MIXrx_Q). The CALBK searches for the differential balance corresponding to a transition point that allows the phase to transition by approximately 180°. The MIXrx_I (MIXrx_Q) operates in normal mode using the differential balance as a search result.

Abstract: There is a need to reduce secondary intermodulation distortion that may occur in a reception circuit of a high-frequency signal processor and a wireless communication system having the same. In test mode, for example, a test signal generating circuit TSGEN generates a test signal RFtst at f_tx±0.5 MHz. The test signal RFtst is input to a mixer circuit MIXrx_I (MIXrx_Q). A correction circuit block CALBK detects an IM2 component resulting from the MIXrx_I (MIXrx_Q). The CALBK varies a differential balance for the MIXrx_I (MIXrx_Q) and concurrently monitors a phase for the IM2 component resulting from MIXrx_I (MIXrx_Q). The CALBK searches for the differential balance corresponding to a transition point that allows the phase to transition by approximately 180°. The MIXrx_I (MIXrx_Q) operates in normal mode using the differential balance as a search result.

Abstract: There is a need to reduce secondary intermodulation distortion that may occur in a reception circuit of a high-frequency signal processor and a wireless communication system having the same. In test mode, for example, a test signal generating circuit TSGEN generates a test signal RFtst at f_tx ±0.5 MHz. The test signal RFtst is input to a mixer circuit MIXrx_I (MIXrx_Q). A correction circuit block CALBK detects an IM2 component resulting from the MIXrx_I (MIXrx_Q). The CALBK varies a differential balance for the MIXrx_I (MIXrx_Q) and concurrently monitors a phase for the IM2 component resulting from MIXrx_I (MIXrx_Q). The CALBK searches for the differential balance corresponding to a transition point that allows the phase to transition by approximately 180°. The MIXrx_I (MIXrx_Q) operates in normal mode using the differential balance as a search result.