Abstract: A method and apparatus for generating a plurality of ECG precordial leads using a precordial central terminal derived from a plurality of electrodes for attachment around the circumference of a patient's upper torso. The apparatus is a device including a plurality of electrodes, an acquisition module including a signal processor coupled to the plurality of electrodes for acquiring electrical signals from the electrodes and for generating a plurality of ECG precordial leads from the acquired electrical signals. According to the method of the invention, an approximation of the electrical potential near the center of the patient's heart (i.e., a precordial central terminal) is generated based on the signals acquired from the plurality of electrodes. The precordial central terminal signal is subtracted from the signal acquired from each electrode attached to the patient's chest in order to generate the precordial leads.

Abstract: The present invention provides systems and methods for the communication of data over telephone lines. A handset orientation tolerant bi-directional acoustic modem according to the invention includes a first transducer operable as a receiving unit under a first condition and as a transmitting unit under a second condition, a second transducer operable as a transmitting unit under the first condition and as a receiving unit under the second condition, and a controller capable of determining the presence of one of the first and the second condition. The presence of the first condition or second condition depends on how the microphone and the speaker of a telephone handset are aligned with respect to the two transducers. The acoustic modem determines the alignment by listening for a detectable dial tone, and then under the first or the second condition, the acoustic modem automatically transmits data to a central site for analysis.

Abstract: An electronic apparatus comprising: a housing; an infrared filter window supported by the housing; and an infrared transceiver mounted in the housing so that infrared light emitted by the infrared transceiver is focused in the vicinity of the infrared window, and radiates from the infrared filter window in an approximately 30 degree illumination cone.

Abstract: An apparatus and method for printing on both sides of a medium by passing the medium through a printing device and printing on oppositely facing portions of the medium during a single pass of the medium through the printing device. Preferably, a first print head prints on one portion while a second print head prints on the other portion. The medium is preferably folded so that after the printing is completed and the folded medium is unfolded, the printed information on one portion of the medium correlates with the printed information on the other portion of the medium. The printed information is preferably data that has been measured with respect to time, and the printed data on the oppositely facing portions correlate with respect to time. Preferably, the data is medical patient data in the form of textual data, physiological waveforms, or a combination of both.

Abstract: An ECG signal is acquired in multiple channels, and sources of interference are filtered from the signals. A covariance matrix is then formed with the channels of data. The invention then employs matrix mathematics to discover a set of eigenvectors that organize the variability of data in a multi-dimensional space along new directions, orthogonal to each other and ranked in order of significance. For each eigenvector, a corresponding eigenvalue is calculated. In addition, coefficients are calculated which correspond to the portion of each eigenvector that is necessary to reconstruct each original vector. From the eigenvector solution of the covariance matrix, the angles between the eigenvectors and the original vectors are determined. The eigenvector coefficients and the angles between the eigenvectors and the original vectors are related by a cosine relationship.

Abstract: A signal acquisition method comprises the steps of recording ECG data signals on a tape in a first direction through a first high pass filter; and acquiring the data from the tape in an analyzer in a reverse direction through a second high pass filter having the same effective characteristics as the first filter.