A Digital Frequency-to-Temperature Converter For Use in Radio Telemetry Systems in Which Temperature is Transmitted Proportional to a Subcarrier Frequency

A digital frequency-to-temperature converter was designed to demodulate the signal from a surgically implanted temperature telemetry transmitter. In addition to providing a digital readout of time and temperature, it provides a signal for analog recording. It win update the time and temperature readout only when two successive frequency measurements of the signal are the same, thus eliminating nearly all erroneous temperature data caused by noise. These time and temperature data are provided in binary coded decimal (BCD) form so that they can be recorded as reliable data in digital form for eventual computer processing. Although the unit is somewhat complex, a primary feature of its design is that a person with no electronics training can easily calibrate and use it by switching three sets of binary numbers, associated with the particular temperature transmitter in use, into the machine.