Abstract: A drill includes an integrated bi-directional orienting means for leveling the device when in use. The bi-directional orienting means preferably comprises a circular bubble level attached to the butt of the drill. It is relatively easy for the drill operator to level the drill by keeping the bubble in the center of the circular level. A tubular level is separately attached to the top of the drill for guidance in the direction perpendicular to the plane of the circular level. In an alternative embodiment, a tubular level is integrally attached at right angles to the circular level. The liquid filled cavity inside the circular level and tubular level is continuous so that the indicator bubble can travel from the tubular level to the circular level and back again. The apparatus may be adhesively attached to the drill or, the drill may include a cavity for receiving and holding the apparatus.

Abstract: An FM-CW radar system with improved range discrimination and improved immunity to clutter, chaff, jamming and multiple target environments. The FM-CW apparatus involves a repetitive cycle including a first, constant-transmitted-frequency (monochromatic) transmission, a linear frequency upsweep as a second period and a linear frequency downsweep as a third period within each transmission frame. Pseudorandom coding is superimposed on the FM-CW waveform, a code word duration being selected to place the first Doppler ambiguity beyond the highest expected equivalent target velocity. The resulting range ambiguities are resolved by means of the unambiguous range-determining capability of the FM-CW feature.

Abstract: A system for measuring a first period of time, for example a period between a pair of pulses, with an extraordinarily high degree of accuracy. Two ramp voltages of different slopes are started in synchronism with the first occurring pulse. The ramp with the largest slope is then sampled and held on receipt of the second occurring pulse. A counter counts a clock of a moderate pulse repetition frequency (PRF) during a second period occurring between the time the ramps are started and the time the amplitude of the ramp of the smaller slope becomes equal to the sampled amplitude of the ramp of the larger slope. The count stored in the counter at the end of the second period is then directly proportional to the first period or is equal thereto. Moreover, the count can be far more precise than it would be by counting the clock PRF during the first period.