Abstract: A system determines the level of paper available in paper supply for printing. The system comprises a signal emitter and a variably activated receiver. The receiver alters an electrical parameter such as a resistance in accordance with the portion of the emitted signal received at the receiver. This alterable electrical parameter is in an electrical circuit that generates a signal proportional to the received portion of the emitted signal. An array of variably activated receivers may be arranged opposite a signal emitter to receive the signal portion not blocked by a paper supply. Alternatively, the array of variably activated receivers may be located adjacent to the signal emitter to receive the portion of the emitted signal reflected from the paper supply. The receiver uses the received or reflected signal to generate a signal having a magnitude proportional to the received or reflected signal.

Abstract: A system determines the level of paper available in paper supply for printing. The system comprises a signal emitter and a variably activated receiver. The receiver alters an electrical parameter such as a resistance in accordance with the portion of the emitted signal received at the receiver. This alterable electrical parameter is in an electrical circuit that generates a signal proportional to the received portion of the emitted signal. An array of variably activated receivers may be arranged opposite a signal emitter to receive the signal portion not blocked by a paper supply. Alternatively, the array of variably activated receivers may be located adjacent to the signal emitter to receive the portion of the emitted signal reflected from the paper supply. The receiver uses the received or reflected signal to generate a signal having a magnitude proportional to the received or reflected signal.

Abstract: A crystal oscillator that is temperature compensated by digitally substrang a correction frequency from the running frequency of the crystal oscillator to provide the required operating frequency. The correction frequency is generated by a digital frequency synthesizer circuit which is controlled by the output of a programmable read-only memory which has been programmed to generate the required correction frequency for each temperature code over the operating temperature range. The temperature code is generated by gating a digital counter with the output of a monostable multivibrator which utilizes a thermistor to make its gate interval proportional to temperature.

Abstract: A thin disk acoustic baffle comprising a thin disk of material having a uue combination of acoustical properties and dimensions to provide optimum attenuation of sound transmission between two points. Optimum sound attenuation is achieved by adjusting the thickness, diameter, and location of the thin disk relative to one of the points to be baffled and by selecting the material of the disk to have acoustic properties such that sound waves diffracted around the edges of the disk cancel the direct waves transmitted through the disk at a particular frequency of interest.

Abstract: A wide band proportional transducer array including a plurality of active oustic elements. The elements are concentrically mounted to form a conical array. A proportionality constant k is selected to be such that a nearly constant composite array impedence is achieved. The proportionality constant relates to the ratio of the resonant frequencies of adjacent elements and inversely as the ratio to their physical sizes. Another embodiment employs a pair of conical arrays which results in a toroidal beam.

Abstract: A tuned plate acoustic projector having a tuned plate that has its periph bonded to and supported by a housing. The outer face of the tuned plate is exposed to a fluid medium in which it is desired to generate acoustic waves. One end of a piezoelectric transducer is in contact with the central region of the inner face of the tuned plate and the other end is in contact with a mass slug that has a relatively large inertia base for the transducer. A compressive bias force is applied to the transducer to maintain the transducer in compression and to thereby prevent the generation of excessive tensile stresses in the transducer during operation. The thickness of the tuned plate is selected or tuned so that the propagation velocity of the flexural waves in the tuned plate matches the acoustic propagation velocity of the external fluid medium.

Abstract: A target simulator system that may be suspended in the ocean to simulate a oving target to a homing weapon. The system includes a receiving transducer for receiving an acoustic signal transmitted by the homing weapon. The acoustic signal is then amplified, doppler shifted, filtered and then retransmitted by a transmitting transducer to the homing weapon. The doppler shift may be selected to have the retransmitted signal simulate a target that is moving towards or away from the homing weapon. The system includes a power compensating circuit and a monitor circuit to assure that the target simulator system is operating within acceptable amplification limits.