Abstract: A welding arrangement (5, 23) for welding pipe sections (6, 7) comprises a power supplying and gas supplying unit (7, 24), a welding unit operatively connected to the power supplying and gas supplying unit and adapted at least in part to displace about the circumference of the pipe (6, 7) during the welding operation, and means whereby the power and gas are transmitted to the welding unit through a transmitting ring (8, 27) sufficient in diameter to extend around the pipe (6, 7) during the welding operation and thereby enabling the power and gas supply unit (7, 24) to remain stationary during the welding operation.

Abstract: A digital oscilloscope includes an amplifier having adjustable gain and offset for producing an output signal in response to an input signal, a triggering system for producing a trigger status signal when the amplifier output signal reaches an adjustable trigger level, and a digitizer for generating a waveform data sequence representing magnitudes of samples of the amplifier output signal acquired at various times with respect to assertion of the trigger status signal. The oscilloscope produces a waveform display on a screen according to the waveform data sequence produced by the digitizer and automatically adjusts the amplifier gain and offset, the trigger level, and the sampling rate of the digitizer so that the waveform data produced by the digitizer provides for a waveform display suitably representative of the time dependent behavior of the input signal.