Abstract: Graphic plotting network methods and apparatus are disclosed for connecting one or more video signal sources, such as computer workstations and/or RGB dameras, to a single plotter. In a preferred embodiment, a video chain unit (VCU) is connected to each of the sources for receiving analog video and/or digital serial and/or digital parallel information, and the VCUs are interconnected in series with one another and with a video processing unit (VPU) which is in turn connected to the plotter. The interconnection is made in series such that any VCU may communicate with the VPU even if other VCUs in the chain are powered off and such that the VPU (and the plotter) can be placed anywhere in the chain. Each VCU has a set of switches for setting the plot parameters, for acquiring a plot, for repeating a plot, and for aborting a plot in process, and an indicator to show when the plotter is ready to acquire a plot.

Abstract: Borehole fluid flow measuring apparatus is disclosed having a body member sized for passage through a wellbore. In a first embodiment of the invention, a thin metallic cross shaped disk is rotatably mounted in the body. Two solenoid coils are mounted in the body, their ends defining a plane facing the disk. The coils are each connected to separate oscillator circuits. Rotation of the disk in response to borehole fluid flow changes the amplitude of oscillation of each oscillator circuit because the impedance of each coil is changed when a metallic vane of the cross shaped disk is in line with the end of the coil. Because the disk is cross shaped, each revolution of the disk generates four pulses from separate demodulator - pulse shaping circuitry connected to the output of each oscillator circuit. One pulse train is selected as the reference train. The other pulse train leads or lags the reference train depending on the direction of rotation.