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Microphone used as a phonocardiograph transducer monitors small amplitude audio signals in the presence of large shock loads and high humidity. It contains a lead zirconate-lead titanate piezoelectric plate encapsulated in a flexible polyurethane resin. The resin is contained in a sealed nylon case having a diameter of less than one inch.
Cylindrical sample container provides a high degree of nuclear stabilization to a nuclear magnetic resonance /nmr/ spectrometer. It is placed coaxially about the nmr insert and contains reference sample that gives a signal suitable for locking the field and frequency of an nmr spectrometer with a simple audio modulation system.
Several methods of modulating a beam of light, which have been described in the literature, utilizing the influence of an electrical signal on the birefringence of certain crystals, will be reviewed. These employ optics which respond to the state of polarization of a light beam, and include intensity modulation, position modulation, and the possibility of an electrically tuned optical filter. The influence of the piezo-optic, or strain contribution to the total electro-optic response in the design of an optoelectronic device will be discussed. Current experimental work in our laboratory in which the strain contribution is separated from the direct effect will be described. The strain-free effect is measured by applying a step voltage to the crystal, and observing the initial response. The electro-optical transient response can be observed with nanosecond time resolution. An electronic sampling technique is used to extract the desired response from photon noise. The stress-free or low-frequency effect is measured similarly but at low audio frequencies. Single crystal tetragonal BaT10 3 has been investigated in detail with the result that the strain-optic contribution to the low frequency effect r_(c) = r_(33)—r_(13) is about 80% of the total, where it is only 10% in KDP and 45% in ADP. The magnitudes of the electro-optic effect, dielectric constant, and other related properties are compared for several materials potentially useful as electro-optic modulators, and some comments are made about the practical problems of building a modulator.
Transmitter audio amplifier module, low pass filter module, summing network modules, and operational amplifier for thin film personal communications and telemetry system
Fitzgeralds piezoelectric disk and theory on audio frequency resonances and sound beams in crystals
Audio waves from radio stations detected by rockets, using technique applicable to plasma diagnostics
Nuclear radiation effect on structural and mechanical relaxation behavior of polytetrafluorethylene at audio frequencies
Continuous and triggered audio frequency noise bands associated with ionospheric lower hybrid resonance frequency observed on OGO 2
Digital method to produce radar reflectivity from analog audio frequency Doppler data extracted from terrain echo signal of CW scatterometer radar
Variable time lapse videoscintiscope in medical applications, discussing implementation of TV camera, signal tape recording and audio activation
Lamp modulator provides visible indication of presence and magnitude of an audio signal carrying voice or data. It can be made to reflect signal variations of up to 32 decibels. Lamp life is increased by use of a bypass resistor to prevent filament failure.
Radio frequency coaxial filter to provide dc isolation and low frequency signal rejection in audio range
Multichannel, continuous audio, still video, TV transmission systems for limited frequency spectrum system
Audio-Visual Satellite Instruction system (AVSIN) for USA - preliminary considerations
Humidity effects on sound velocity in air at constant temperature and normal atmospheric pressure in lower audio frequency range
The testing program with the ATS-1 and ATS-3 spacecraft showed that geostationary satellites can provide superior communications and position surveillance for mobile craft. Inexpensive modifications to conventional mobile communications equipment aboard the craft can provide reliable, high quality voice and digital communications with distant ground stations and other vehicles, and automatic surveillance of the positions of all the craft by a ground facility. The tests also demonstrated the location and automatic readout of remote data collection platforms. Frequency modulation signals with the narrow audio and radio frequency bandwidths of terrestrial mobile radio communications were relayed through the VHF transponders of the geostationary satellites. The voice and digital communications were far superior in reliability and quality to long-distance mobile communications by other means. It was shown that one satellite can provide nearly uniform high quality performance over approximately one-third of the earth's surface. Position fixes by range measurement from the two satellites were accurate to approximately one nautical mile, except near the equator and the poles.
The VHF transponders of the ATS-1 and ATS-3 geostationary satellites were used in ranging and position fixing experiments. An interrogation signal was transmitted from a ground terminal to ATS-3, which relayed it to the vehicle transponders. The vehicle that was addressed repeated the signal and its response was relayed back through both satellites to the ground terminal, where propagation times were measured; lines-of-position and fixes were computed. The 0.43 second tone-code ranging signal contained a single audio tone frequency. Ambiguity was resolved and user craft identified by a simple digital code. Seven vehicles were used in the test: three aircraft, two ships, an oceanographic buoy, and a truck. Ionospheric and multipath effects were studied. It is concluded that a VHF system could have an accuracy of + or - one nautical mile for ships and aircraft if calibration transponders are used to monitor the ionosphere.
A compilation of improvements and test results is presented. The LPF preceding the VOGAD preamplifier on the M1 board was tested in regard to its rejection of possible timing noise resulting from operating at the lowest standard rate of 9.6 KHz. The dynamic range of the VOGAD preamplifier, also on board M1 was extended to a full 30 d while introducing a distortion of less than 5% into the audio signal being processed.