Abstract: A heart rate monitor can comprise a heart rate sensor and a strap. The heart rate sensor can contact a tail of an equine and comprise an optical heart rate module (OHR) and a transmitter. The OHR module can output light into skin of the equine, receive reflected light, and convert the reflected light into electrical signals. The transmitter can wirelessly transmit heart rate data based on the electrical signals. The strap can removably receive the heart rate sensor and removably couple to the tail of the equine.

Abstract: A topside buoy system is disclosed for relaying a status of a diver between a monitoring station and a diver's wearable device and scuba tank pod. The communication may be carried by sonar signals underwater and may be transmitted by short-range communication methods through air. An application on the command station may display diver status information and may receive and transmit messages between the command station and the wearable device of the diver via the topside buoy. The diver location data may be determined relative to the topside buoy by determining a time delay of the sonar signal between the wearable device and the topside buoy, by a plurality of transducers configured to detect an angle from which the sonar signal originated, and a depth of the diver included in the sonar signal.

Abstract: A frequency synthesizer has a voltage controlled oscillator comprising a voltage controlled capacitor having a first terminal and a second terminal. A positive control voltage is applied to the first terminal of the voltage controlled capacitor and a negative control voltage is applied to the second terminal of the voltage controlled capacitor, causing the varactor to operate in a reverse biased state. A circuit for generating a negative control voltage is provided in a phase-locked loop circuit. The circuit includes a negative DC generator for generating a negative DC voltage from an AC signal, and a programmable variable attenuator for selectably attenuating the negative control voltage.

Abstract: A frequency synthesizer has a voltage controlled oscillator comprising a voltage controlled capacitor having a first terminal and a second terminal. A positive control voltage is applied to the first terminal of the voltage controlled capacitor and a negative control voltage is applied to the second terminal of the voltage controlled capacitor, causing the varactor to operate in a reverse biased state. A circuit for generating a negative control voltage is provided in a phase-locked loop circuit. The circuit includes a negative DC generator for generating a negative DC voltage from an AC signal, and a programmable variable attenuator for selectably attenuating the negative control voltage.

Abstract: A programmable, low-current voltage source for small-signal electronic equipment, such as portable cellular telephones, is achievable by generating and applying a bias voltage and a reference voltage across a voltage divider circuit. Consequently, a low-current output voltage is generated at the center junction of the voltage divider circuit. Adjustment of the low-current output voltage level is accomplished by adjusting either the bias voltage level and/or the reference voltage level. The adjustment of the bias voltage level and/or the reference voltage level, in turn, is controlled by a programmable, microprocessor-based waveform generator.