Abstract: An excitation unit applies, to an excitation coil, an excitation voltage with a voltage level alternately changing between a first high voltage value higher than a reference voltage value and a first low voltage value lower than the reference voltage value. The excitation unit includes a comparison circuit and a voltage switching circuit. The comparison circuit outputs a comparison signal having a voltage level switching between a high level and a low level depending on whether a detection voltage is greater than, or equal to or less than, a threshold voltage. The voltage switching circuit switches the voltage level of the excitation voltage between the first high voltage value and the first low voltage value according to the voltage level of the comparison signal.

Abstract: A first decision unit of an AC leakage detection section outputs a first output signal with a signal level depending on the level of a corrected first voltage signal output from a correction unit relative to a first threshold value. An excitation unit of a DC leakage detection section applies, to an excitation coil, an excitation voltage having an excitation frequency. A DC component detection unit outputs a second voltage signal representing magnitude of a DC component of the voltage obtained by a current-detecting resistor. A second decision unit outputs a second output signal having a voltage level depending on the level of the second voltage signal relative to a second threshold value. The DC leakage detection section includes a low-pass filter provided between an input terminal electrically connected to a connection point between the excitation coil and the current-detecting resistor and the excitation coil.

Abstract: An excitation unit applies, to an excitation coil, an excitation voltage with a voltage level alternately changing between a first high voltage value higher than a reference voltage value and a first low voltage value lower than the reference voltage value. The excitation unit includes a comparison circuit and a voltage switching circuit. The comparison circuit outputs a comparison signal having a voltage level switching between a high level and a low level depending on whether a detection voltage is greater than, or equal to or less than, a threshold voltage. The voltage switching circuit switches the voltage level of the excitation voltage between the first high voltage value and the first low voltage value according to the voltage level of the comparison signal.

Abstract: A first decision unit of an AC leakage detection section outputs a first output signal with a signal level depending on the level of a corrected first voltage signal output from a correction unit relative to a first threshold value. An excitation unit of a DC leakage detection section applies, to an excitation coil, an excitation voltage having an excitation frequency. A DC component detection unit outputs a second voltage signal representing magnitude of a DC component of the voltage obtained by a current-detecting resistor. A second decision unit outputs a second output signal having a voltage level depending on the level of the second voltage signal relative to a second threshold value. The DC leakage detection section includes a low-pass filter provided between an input terminal electrically connected to a connection point between the excitation coil and the current-detecting resistor and the excitation coil.

Abstract: A magnetic core is electromagnetically coupled to two conductors that allow an AC current to flow through. An exciter is configured to supply a winding with an excitation current that is an alternating current. A current detector is configured to detect a current flowing through the winding. A DC component detector is configured to detect a DC component level from the current detected with the current detector. Two contact elements are respectively disposed along the two conductors. A discrimination controller is configured to: turn the two contact elements on when the DC component level detected with the DC component detector is less than or equal to a threshold; turn the two contact elements off when the DC component level detected with the DC component detector is greater than the threshold; and turn the two contact elements off in de-energized condition.

Abstract: A magnetic core is electromagnetically coupled to two conductors that allow an AC current to flow through. An exciter is configured to supply a winding with an excitation current that is an alternating current. A current detector is configured to detect a current flowing through the winding. A DC component detector is configured to detect a DC component level from the current detected with the current detector. Two contact elements are respectively disposed along the two conductors. A discrimination controller is configured to: turn the two contact elements on when the DC component level detected with the DC component detector is less than or equal to a threshold; turn the two contact elements off when the DC component level detected with the DC component detector is greater than the threshold; and turn the two contact elements off in de-energized condition.

Abstract: A video data transmitter apparatus generates and transmits a multi-value amplitude modulation signal by performing a multi-value amplitude modulation of a plurality of N bits per one symbol according to video data of a video signal or a color signal constituting the video signal, or a brightness signal and a color-difference signal. A data separator portion separates the video data into first to N-th pixel data, a difference calculator portion calculates (N?1) pieces of predetermined difference information based on the separated first to N-th pixel data, and a multi-value amplitude modulator portion performs a multi-value modulation so that predetermined N-bit data corresponds to a multi-value signal level closest to an intermediate level having an intermediate value between a maximum level and a minimum level of the multi-value signal level of the multi-value amplitude modulation signal.

Abstract: In a video signal transmitter apparatus that removes a part of a blanking interval of a video signal, generates a converted video signal, based on the video signal including an active interval including video data and the blanking interval excluding the video data, a frequency divider divides a frequency of a pixel clock in synchronization with the video signal by a ratio of transmission frequency division, generate and output a frequency-divided clock as a converted pixel clock. A controller controls a first storage unit to write the video signal for the active interval of the video signal, and read the video signal for the active interval of the converted video signal and output a read video signal as the converted video signal, and to remove a part of a signal included in a horizontal blanking interval existing periodically every horizontal line for the blanking interval of the video signal.

Abstract: A video data transmitter apparatus generates and transmits a multi-value amplitude modulation signal by performing a multi-value amplitude modulation of a plurality of N bits per one symbol according to video data of a video signal or a color signal constituting the video signal, or a brightness signal and a color-difference signal. A data separator portion separates the video data into first to N-th pixel data, a difference calculator portion calculates (N?1) pieces of predetermined difference information based on the separated first to N-th pixel data, and a multi-value amplitude modulator portion performs a multi-value modulation so that predetermined N-bit data corresponds to a multi-value signal level closest to an intermediate level having an intermediate value between a maximum level and a minimum level of the multi-value signal level of the multi-value amplitude modulation signal.

Abstract: An optical transmission system for optically transmitting information between apparatuses via an optical transmission path. The system includes: a sending unit that emits, to the optical transmission path, excitation light for detecting an inter-apparatus connection via the path; a responding unit that receives the excitation light from the path and emits detection light to the path using light energy of the excitation light; a response receiving unit that receives the detection light from the path and outputs a detection light current; a detecting unit that detects presence/absence of the inter-apparatus connection based on the detection light current; a light signal transmitting unit that emits, to the path, a light signal for optically transmitting the information based on the detection result by the detecting unit; and a light signal receiving unit that receives the light signal from the path.

Abstract: A multilevel amplitude modulation device for generating, from digital data, a multilevel amplitude modulation signal having four or more signal levels and outputting the generated signal, including: an average level calculator that selects one of a plurality of preliminarily prepared different candidates for a code word building method such that average level of a symbol array, obtained by adding a symbol for a code word of digital data to be transmitted to one or more already outputted symbols included in a multilevel amplitude modulation signal already outputted, is most approximate to voltage center of the four or more signal levels, and outputs a selection signal indicating the selected method; a signal converter that forms a codeword of the digital data in accordance with the method indicated by the selection signal; and a multilevel modulator that generates a multilevel amplitude modulation signal using the codeword and outputs the generated signal.

Abstract: A video data transmitter apparatus generates and transmits a multi-value amplitude modulation signal by performing a multi-value amplitude modulation of a plurality of N bits per one symbol according to video data of a video signal or a color signal constituting the video signal, or a brightness signal and a color-difference signal. A data separator portion separates the video data into first to N-th pixel data, a difference calculator portion calculates (N?1) pieces of predetermined difference information based on the separated first to N-th pixel data, and a multi-value amplitude modulator portion performs a multi-value modulation so that predetermined N-bit data corresponds to a multi-value signal level closest to an intermediate level having an intermediate value between a maximum level and a minimum level of the multi-value signal level of the multi-value amplitude modulation signal.

Abstract: A video data transmitter apparatus generates and transmits a multi-value amplitude modulation signal by performing a multi-value amplitude modulation of a plurality of N bits per one symbol according to video data of a video signal or a color signal constituting the video signal, or a brightness signal and a color-difference signal. A data separator portion separates the video data into first to N-th pixel data, a difference calculator portion calculates (N?1) pieces of predetermined difference information based on the separated first to N-th pixel data, and a multi-value amplitude modulator portion performs a multi-value modulation so that predetermined N-bit data corresponds to a multi-value signal level closest to an intermediate level having an intermediate value between a maximum level and a minimum level of the multi-value signal level of the multi-value amplitude modulation signal.

Abstract: In a video signal transmitter apparatus that removes a part of a blanking interval of a video signal, generates a converted video signal, based on the video signal including an active interval including video data and the blanking interval excluding the video data, a frequency divider divides a frequency of a pixel clock in synchronization with the video signal by a ratio of transmission frequency division, generate and output a frequency-divided clock as a converted pixel clock. A controller controls a first storage unit to write the video signal for the active interval of the video signal, and read the video signal for the active interval of the converted video signal and output a read video signal as the converted video signal, and to remove a part of a signal included in a horizontal blanking interval existing periodically every horizontal line for the blanking interval of the video signal.

Abstract: A comparator circuit compares a test pattern generated by a test pattern generator circuit, with a test pattern transmitted to a memory card and returned from the memory card. A control circuit determines a bandwidth corresponding to frequency components correctly transmitted between a host apparatus and the memory card, based on the returned test pattern, and selects an encoding method requiring a maximum available bandwidth. The control circuit generates a notification message indicating the selected encoding method, and encodes the notification message using the selected encoding method, and transmit the encoded notification message to the memory card. The control circuit establishes communication between the host apparatus and the memory card, when receiving a response message including an acknowledgement to the notification message, from the memory card.

Abstract: A multilevel amplitude modulation device for generating, from digital data, a multilevel amplitude modulation signal having four or more signal levels and outputting the generated signal, including: an average level calculator that selects one of a plurality of preliminarily prepared different candidates for a code word building method such that average level of a symbol array, obtained by adding a symbol for a code word of digital data to be transmitted to one or more already outputted symbols included in a multilevel amplitude modulation signal already outputted, is most approximate to voltage center of the four or more signal levels, and outputs a selection signal indicating the selected method; a signal converter that forms a codeword of the digital data in accordance with the method indicated by the selection signal; and a multilevel modulator that generates a multilevel amplitude modulation signal using the codeword and outputs the generated signal.

Abstract: A comparator circuit compares a test pattern generated by a test pattern generator circuit, with a test pattern transmitted to a memory card and returned from the memory card. A control circuit determines a bandwidth corresponding to frequency components correctly transmitted between a host apparatus and the memory card, based on the returned test pattern, and selects an encoding method requiring a maximum available bandwidth. The control circuit generates a notification message indicating the selected encoding method, and encodes the notification message using the selected encoding method, and transmit the encoded notification message to the memory card. The control circuit establishes communication between the host apparatus and the memory card, when receiving a response message including an acknowledgement to the notification message, from the memory card.

Abstract: An optical transmission system for optically transmitting information between apparatuses via an optical transmission path. The system includes: a sending unit that emits, to the optical transmission path, excitation light for detecting an inter-apparatus connection via the path; a responding unit that receives the excitation light from the path and emits detection light to the path using light energy of the excitation light; a response receiving unit that receives the detection light from the path and outputs a detection light current; a detecting unit that detects presence/absence of the inter-apparatus connection based on the detection light current; a light signal transmitting unit that emits, to the path, a light signal for optically transmitting the information based on the detection result by the detecting unit; and a light signal receiving unit that receives the light signal from the path.

Abstract: A data communication apparatus is highly concealable and significantly increases time necessary for an eavesdropper to analyze cipher text. A multi-level code generation section generates, by using predetermined key information, a multi-level code sequence in which a signal level changes so as to be random numbers. The multi-level processing section combines a multi-level code sequence and information data, and generates a multi-level signal having a level corresponding to a combination of the multi-level code sequence and the information data. In the multi-level code generation section, a random number sequence generation section generates a binary random number sequence by using the predetermined key information. A multi-level conversion section generates a multi-level code sequence from the binary random number sequence in accordance with a predetermined encoding rule.

Abstract: A data communication apparatus wherein stealthiness is enhanced by significantly increasing the time required for a wiretapper to decrypt an encrypted text. The data communication apparatus is constituted by connecting a data transmitting apparatus and a data receiving apparatus via a transmission path. The data transmitting apparatus receives a first predetermined initial value (key information) and information data, generates a multi-valued signal, the level of which varies substantially in a random number manner, and converts the multi-valued signal to a modulated signal of a predetermined modulation format for transmission. The data receiving apparatus demodulates the modulated signal to output the multi-valued signal, and then reproduces the information data from the multi-valued signal and a received second predetermined initial value (key information).