A power detector which samples the output signal from a communications device and produces a control signal proportional to the transmit power level, comprising a series of diode detectors where the sampled signal is divided between the diode detectors by an attenuator cascade. A document cover is positioned at a plurality of open positions to a document table. The elongate member is insertable in a first corresponding groove in the frame and in a second corresponding groove in the frame, the first and second corresponding grooves being separated by a hinge. At this time, the voltages across both terminals of IGBT corresponding with the snubber capacitors being charged becomes zero, and ZVS is achieved. A section-filtering unit included in the DTV receiver is able to use table identification extension fields of a plurality of ETTs for section-filtering a pertinent event or channel ETT from the ETTs.