The development of Thermoscan Instant Thermometer.
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Analog-Digital Conversion↗
Biomedical subjects
J Fraden
Publications and source records attributed to J Fraden.
Estimation of body sites temperatures from tympanic measurements.
For many years, measurement of body temperature in routine medical practice was limited to oral, rectal and axillary sites. Recent introduction of infrared non-contact thermometers for the auditory canal requires the establishing of temperature relationships between the ear and more traditional thermometry sites. Since an auditory canal is exposed to the environment, the infrared readings from it are influenced by ambient temperature. A linear model of thermal gradients in the vicinity of an ear canal allows us to find simple formulas connecting temperatures taken from the ear with those from traditional core sites like bladder or pulmonary artery, in addition to rectal and oral. The formulas contain environment coupling coefficients. Their values have been found experimentally by measuring body temperatures from subjects in a walk-in environmental chamber and from multiple clinical studies. The derived coefficients are used in the Thermoscan PRO-1 Instant Thermometer to calculate core, oral and rectal equivalent temperatures.
Adult↗
QRS wave detection.
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Electrocardiography↗
Synchronization in biotelemetry systems with time division of channels.
In order to improve synchronization in biotelemetry systems, a relative pulse-width selector was designed. It employs a sawtooth generator, sample-and-hold and analogue comparator. The use of this selector creates a possibility of reducing the increase in the synchronizing pulse with respect to the channel pulses and eliminating tuning the transmitter's modulator and receiver's selector to each other. Two different selectors are described: a simple one for two different pulse widths and a more complicated one with a counter for any setting of pulse width in the system.
Biomedical Engineering↗
Destruction of noise in biotelemetry.
The difference in statistical characteristics between physiological signals and noise creates the possibility of designing a selective circuit to separate signals from noise. Analysis shows that by an extremely low signal-to-noise ratio before the pulse conditioner in a biotelemetry system, the mixture of normal and spurious pulses are present at the demodulator input. The system of noise destruction analyzes the sequential distances between two following pulses and blanks all spurious pulses using the criteria of high autocorrelation of physiological signals in short intervals. Evaluation of the circuit demonstrates a dramatic increase in accuracy in the presence of strong interference because the system of noise destruction performs a linear extrapolation of free-of-noise parts of pulse flow into destroyed spaces. The equations to calculate selective thresholds and output errors are delineated. The noise destructor is especially useful in long-term monitoring and automatic data analysis because it prevents a formation of sharp noisy spikes at the biotelemetry system's output.
Biomedical Engineering↗