Telemetry system utilizing miniature, single-channel, crystal-controlled transmitter is described suitable for biomedical applications. Receiver used in conjunction with transmitter is narrowband superheterodyne FM receiver with crystal control in both conversion stages.

Westbrook, R. M.↗

NASA NTRS1972

Use of implantable telemetry systems for study of cardiovascular phenomena.

Preliminary observations of cardiovascular function have been made in four chimpanzees using multichannel implantable units. Measurements of right- and left-sided pressures were periodically made in these animals over a four-month period, including continuous observations for selected 24-hour periods. Pressures recorded with animals in an awake, unanesthetized, unrestrained state were much lower than pressures reported for restrained animals in similar situations. Diurnal variations of pressure tended to occur, but were not as clear-cut as those reported to occur for humans. The ability to implant a transmitter chronically and receive useful multichannel information in the chimpanzee encourages the future use of such implant devices as part of the control system for an artificial heart or directly for use in man.

Sandler, H.↗

NASA NTRS1972

An ingestible temperature-transmitter

Pill-sized transmitter measures deep body temperature in studies of circadian rhythm and indicates general health. Ingestible device is a compromise between accuracy, circuit complexity, size and transmission range.

Pope, J. M.↗

NASA NTRS1972

A multichannel electromagnetic flowmeter telemetry system.

An eight-channel biomedical telemetry system provides four channels of blood flow measurements in addition to blood-pressure and EKG data. Emphasis is placed on the amplifiers and signal conditioning circuitry required for interfacing of the electromagnetic flow transducers with the transmission and modulation subsystems. The large number of data channels permits measurement of flow distribution as well as total cardiac output. The batteries and electronics for four channels (blood flow) weigh about 500 g and have a volume of 250 cu cm.

Fryer, T. B.↗

NASA NTRS1972

Single and multichannel implanted telemetry systems.

Description of improved single-channel and multichannel telemetry systems designed for measurements of single and multiple physiological parameters, respectively, with adequate accuracy. The systems include a single-channel biopotential transmitter, a temperature transmitter, a pressure transmitter, and a multichannel transmitter for implant telemetric applications.

Sandler, H.↗

NASA NTRS1972

A narrowband, crystal controlled biomedical telemetry system.

A miniature, single-channel, crystal-controlled transmitter has been developed for biomedical applications. A narrow-band frequency modulation (plus or minus 7 kHz) of the RF is used to achieve maximum operating range with minimum transmitting power. The radiated power is limited to stay within the 50 microvolts/m at 15 m FCC requirement for low-power transmitters in the 88- to 108-MHz band. This technique offers a number of advantages. First only manufacturer's type approval is required for the device and the user does not need a license. Second maximum operating range can be achieved within the FCC power limitations by using a narrow-band that is consistent with the required medical information bandwidth. A third advantage in using the 88- to 108-MHz band is that the commercial FM stations are relatively widely spaced and carefully regulated so that by selecting the transmitter's frequency in the guard band between stations, minimum interference from other transmitter sources is encountered.

Westbrook, R. M.↗

NASA NTRS1972

Miniature battery-operated electromagnetic flowmeter

Explore the source record for details and available documents.

Fryer, T. B.↗

NASA NTRS1971

Miniature battery-operated electromagnetic system for blood flow measurements

System consisting of solid state electronics package and a pair of standard flow-transducer cuffs is useful in cardiovascular studies. Device shows good zero stability and calibrations, and low noise levels.

Fryer, T. B.↗

NASA NTRS1971

Low power electromagnetic flowmeter providing accurate zero set

A low power, small size electromagnetic flowmeter system is described which produces a zero output signal for zero flow. The system comprises an air core type electromagnetic flow transducer, a field current supply circuit for the transducer coils and a pre-amplifier and demodulation circuit connected to the output of the transducer. To prevent spurious signals at zero flow, separate, isolated power supplies are provided for the two circuits. The demodulator includes a pair of synchronous rectifiers which are controlled by signals from the field current supply circuit. Pulse transformer connected in front of the synchronous rectifiers provide isolation between the two circuits.

Fryer, T. B.↗

NASA NTRS1971

RF-controlled implantable solid state switch

Miniature, totally implantable, solid state RF-controlled switching circuit for biotelemetry systems consumes zero power in off condition and turns on or off by pulse of RF energy. Switch, the size of small coin, is reducible by integrated circuit techniques.

Fryer, T. B.↗

NASA NTRS1971