Abstract: A communication apparatus (100 and 100A to 100C) includes a first communication unit (110), a second communication unit (110), and a control unit (140 and 140A to 140C). The first communication unit (110) performs wireless communication via an upper communication path. The second communication unit (110) communicates with a terminal apparatus (200 and 200B) via a selected communication path that is one of a plurality of lower communication paths including a wireless communication path and a wired communication path. The control unit (140 and 140A to 140C) detects whether or not communication using the selected communication path has an effect on the upper communication path, and, when the effect is detected, estimates, for each combination of the plurality of lower communication paths and the upper communication path, a communication state of the upper communication path and the lower communication path included in the combination.

Abstract: A power line communication system which enables high quality communication utilizing a pair of power lines connected to a vehicle mounted battery, has a pair of communication lines connected to a pair of power lines, respectively, to communicate a high frequency signal of 1 MHz or more. This system has a balance filter which is interposed between each of the communication lines and a vehicle mounted communication apparatus, the filter, a circuit configuration of which is formed in balance type. The communication system also has a pair of electrically balanced lines which are connected between the balance filter and each of the communication apparatuses and are power-fed from the battery, for performing communication between the communication apparatuses.

Abstract: In a method for determining whether multiple power outlets in a 3-wire power line connection are connected to a same outer wire (P1 or P2), the hot terminal of a first power outlet is identified and a first zero cross time of the hot terminal to which AC voltage is applied is detected. The hot terminal of a second power outlet is identified, and second zero cross time of the hot terminal to which AC voltage is applied is detected. It is determined that the first power outlet and the second power outlet are connected to the same power line if the time elapsed ?T from the first zero cross time of the first power outlet to the second zero cross time of the second power outlet is an integral multiple of the AC voltage cycle.

Abstract: A power line communication system which enables high quality communication, utilizing a pair of power lines 12, 13 connected to a vehicle mounted battery 10, has a pair of communication lines 18 connected to a pair of power lines 12, 13, respectively, to communicate a high frequency signal of 1 MHz or more. This system has a balance filter 26 which is interposed between each of the communication lines 18 and a vehicle mounted communication apparatus 22, the filter 26, a circuit configuration of which is formed in balance type. The communication system also has a pair of electrically balanced lines 28 which are connected between the balance liter 26 and each of the communication apparatuses 22 and are power-fed from the battery 10, for performing communication between the communication apparatuses 22.

Abstract: In a method for determining whether multiple power outlets in a 3-wire power line connection are connected to a same outer wire (P1 or P2), the hot terminal of a first power outlet is identified and a first zero cross time of the hot terminal to which AC voltage is applied is detected. The hot terminal of a second power outlet is identified, and second zero cross time of the hot terminal to which AC voltage is applied is detected. It is determined that the first power outlet and the second power outlet are connected to the same power line if the time elapsed AT from the first zero cross time of the first power outlet to the second zero cross time of the second power outlet is an integral multiple of the AC voltage cycle.

Abstract: A polyvinylacetal resin powder with a low metal content, being excellent in transparency, moisture resistance and electrical insulating properties and having a large specific surface area, and a process for its production, are presented. A polyvinylacetal resin powder obtained by reacting polyvinyl alcohol and an aldehyde in the presence of an acid catalyst, which has an acetalization degree of at least 60 mol %, a specific surface area of from 1.50 to 3.50 m2/g, a bulk density of from 0.12 to 0.19 g/cm3, an average particle diameter of from 0.5 to 2, 5 ?m and a metal content of at most 80 ppm.

Abstract: A polyvinylacetal resin powder with a low metal content, being excellent in transparency, moisture resistance and electrical insulating properties and having a large specific surface area, and a process for its production, are presented. A polyvinylacetal resin powder obtained by reacting polyvinyl alcohol and an aldehyde in the presence of an acid catalyst, which has an acetalization degree of at least 60 mol %, a specific surface area of from 1.50 to 3.50 m2/g, a bulk density of from 0.12 to 0.19 g/cm3, an average particle diameter of from 0.5 to 2, 5 ?m and a metal content of at most 80 ppm.