Abstract: A method is disclosed for setting a master node of a ring network that has adjacently connected nodes situated on rightward and leftward lines of a bidirectional transmission channel. The method includes the steps of: counting the number of nodes interposed between a designated node and each node other than the designated node on the rightward and leftward lines of the bidirectional transmission channel; and setting one of the nodes as the master node. The master node satisfies a relation of, NHC_L=NHC_R or NHC_L=NHC_R-1, wherein NHC_L is the number of interposed nodes counted from the leftward line, and NHC_R is the number of interposed nodes counted from the rightward line.

Abstract: A driver circuit for generating a driving signal by pulse-width modulation (PWM) includes a half-bridge circuit formed essentially of a pair of series-connected FETs. When the level of an ultrasonic signal, or of the driving signal, is to be maximized, the individual FETs are switched at a switching frequency matched to the frequency of the driving signal. When the level of the ultrasonic signal, or the driving signal is to be reduced, on the other hand, the individual FETs are switched with specific timing determined based on the frequency of a clock signal of which period is shorter than that of the driving signal.

Abstract: An ultrasonic transmitter generates a reference signal based on a clock signal of a specific frequency and a control signal made up of binary values 0 and 1 for controlling how the level (High or Low) of a carrier drive signal should change, and generates an analog signal constituting the carrier drive signal by pulse-duration-modulating the reference signal. Produced from the carrier drive signal, a driving pulse signal is shaped into a curved waveform having a gradually rising leading edge and a gradually falling trailing edge as the amplitude of the carrier drive signal is gradually increased and decreased based on the control signal.

Abstract: An onboard equipment network system comprises a radar core device, a GPS core device, an echo sounder core device and a sonar core device and display devices which are connected to a network through a hub. Each core device includes a detecting section or a positioning section, as well as a control section, a power supply section and a data transmitter for transmitting detecting signals or positioning signals, while each display device includes a command section for transmitting command data to the individual core devices for setting their operating conditions and a display section for displaying image data received from the individual core devices. The command data is transmitted using Transmission Control Protocol (TCP) while the image data is transmitted using User Datagram Protocol (UDP).

Abstract: A melting and pressure casting device characterized in that it comprises a cylindrical electric heating means set in a closed chamber reducible and increasable in gas pressure, a vertically long crucible set in the heating means, a mold provided below the crucible and connected thereto, and an upper sprue communicating between the lower portion of the pouring cup and the sprue formed in the mold, wherein the melt for casting is held by its surface tension in the pouring cup and the melt thus held is poured under pressure by pressurizing the chamber into the mold through the upper sprue to thereby make a casting.