Abstract: A structure and method to further reduce the dielectric constant (capacitance) of high density plasma chemical vapor deposited silicon dioxide (SiO2 12). The dielectric constant of voids (i.e. air pockets) is close to k=1.0, and therefore the microvoids reduce the effective dielectric constant of the silicon dioxide 12. Use of HDPCVD conditions avoids residual hydrogen, which would degrade the dielectric constant.

Abstract: A drop height recorder apparatus includes a housing suitable for packaging for shipment from an origin point to a destination point, a triaxial accelerometer provides three signals to corresponding high gain and low gain channels. The three high gain channel signals are full wave rectified to change any negative signals to positive signals for summing into a single high gain "zero G" (free-fall) channel. AN analog to digital converter is connected to the three low gain channels, the single high gain channel, and to auxiliary sensors for digitizing the analog signals. A recorder has a programmable controller connected to the ADC for setting the digital sampling rate. The digitized low gain channel signals are passed through a digital trigger threshold comparator for comparison with a reference signal for generating event detecting trigger signals on the way to a delay memory which also receives the digitized high gain zero G signal and auxiliary signals.

Abstract: A seismic triggered seismograph (10) has a transducer (12) that measures particle vibration along three orthogonal axes and a microphone (14) which measures atmospheric overpressure. The four parameters measured produce signals which are passed through delay circuits (58, 60, 62, 90) and then connected for recording on magnetic tape (21). The seismic signals are examined before being input to the delay circuits (58, 60, 62) and when any of the signals exceeds a predetermined threshold, a tape transport (154) and recording mechanism are activated so that the signals are recorded when they emerge from the delay circuits. Both the delay circuits (58, 60, 62, 90) and the magnetic recording are implemented with analog format. At the end of a predetermined time interval following a seismic event, a calibration signal is applied to the magnetic recording. Following the calibration signal, the transducer (12) is activated by a standard amplitude signal for indicating calibration of the transducer (12).