Abstract: A cardiovascular monitor having improved safety features and data transmission ability. Sensing devices placed on a patient's body, such as electrocardiogram electrodes and phonocardiogram microphones, are electrically isolated from the data recorder and AC powerline, thereby protecting the patient from dangerously high voltages existing in the recorder and the external power source. Isolation amplifiers are employed in the signal conditioning circuitry at the front end of the recorder. Special isolation transformers are also used to prevent ground loop currents between the signal conditioner and the recorder thus minimizing noise due to powerline leakage. Similarly, isolation amplifiers are used during the playback mode between the recorder and a data processor to avoid ground loop currents between the recorder and the processor.

Abstract: An interference resistant biomedical transducer for monitoring the acoustic output of a patient's cardiac or respiratory system which provides a high degree of rejection of acoustic noise and spurious electromagnetic signals. The transducer comprises a piezoelectric diaphragm assembly having electrodes which produce a differential output signal. The transducer housing includes a massive metal disc and a compliant handle which provide a mechanical filter to remove undesired signals such as those related to motion of the patient and ambient acoustic noise.

Abstract: An acoustic transducer with high sensitivity and low resonance frequency is constructed of a cylinder having inner and outer layers rigidly bonded together. At least one layer is a thickness poled piezoelectric material. The cylinderical can be closed by end caps to shift nodal locations.

Abstract: A subseafloor simulator for measuring acoustical and other physical propees of sediments at temperatures and pressures that simulate the real ocean environment. A pressure chamber has a porous piston to exert a required overburden pressure to simulate the weight of the mineral grains. An inlet port allows the fluid pressure inside the pressure chamber to be independently controlled. Acoustic and thermal transducers are mounted on the bottom of the pressure chamber. Electronic equipment is used for the acoustic and thermal measurements and the measurement of sample pressures and temperatures. A circulating thermal bath controls the temperature of the sediment sample and the pressure chamber.

Abstract: An improved transducer for generating and detecting shear waves using pielectric bimorph elements. A plurality of pairs of bimorph elements are formed by rigidly attaching together two individual lengths of piezoelectric material with each dimensioned to provide a length and width substantially greater than its thickness. The plurality of bimorph pairs are mounted in a configuration such that each pair is separated by a layer of high compliance material with the electrical polarization of each piezoelectric element pointing in the same direction. Electrical potential applied simultaneously to the electrodes of the individual pairs causes the entire end face of the transducer to perform a shearing motion which will generate or detect acoustic waves in materials in contact with the face.