Abstract: A method of indicating operational status of an electronic device, the device providing an indication of device operational status as a result of a self-test, the method including the following steps: monitoring an environmental condition; changing an indication of device operational status from a first indication to a second indication if the monitored environmental condition changes from a first condition to a second condition, this changing step being performed without performing a self-test. In certain embodiments, the monitored environmental condition is a monitored temperature, the first condition is a first temperature and the second condition is a second temperature. The electronic device may be battery-operated, in which case the self-test is a battery capacity test.

Abstract: A method of indicating operational status of an electronic device, the device providing an indication of device operational status as a result of a self-test, the method including the following steps: monitoring an environmental condition; changing an indication of device operational status from a first indication to a second indication if the monitored environmental condition changes from a first condition to a second condition, this changing step being performed without performing a self-test. In certain embodiments, the monitored environmental condition is a monitored temperature, the first condition is a first temperature and the second condition is a second temperature. The electronic device may be battery-operated, in which case the self-test is a battery capacity test.

Abstract: An electronic device, such as a defibrillator/heart monitor, monitors a battery having a memory for an error condition while the battery is operating the device. If the electronic device finds an error condition with the battery, it transmits error data to a mailbox located in the battery's memory. Other electronic devices or battery support units, or even this electronic device at a later date, can read the error data in the mailbox and take an appropriate action. For example, the electronic device can read the mailbox and, if it finds error data placed there by itself, another electronic device, or a battery support unit, enables an indicator, such as an indicator that informs a user that maintenance needs to be performed on the battery.

Abstract: A method of indicating operational status of an electronic device, the device providing an indication of device operational status as a result of a self-test, the method including the following steps: monitoring an environmental condition; changing an indication of device operational status from a first indication to a second indication if the monitored environmental condition changes from a first condition to a second condition, this changing step being performed without performing a self-test. In certain embodiments, the monitored environmental condition is a monitored temperature, the first condition is a first temperature and the second condition is a second temperature. The electronic device may be battery-operated, in which case the self-test is a battery capacity test.

Abstract: A method of maintaining an electronic device, the method including the steps of monitoring ambient an environmental condition such as temperature or humidity; monitoring a self-test initialization criterion; performing an automatic device self-test if the self-test criterion is met and if the environmental condition is within a predetermined range; and not performing the automatic device self-test if the self-test criterion is met but the environmental condition is outside the predetermined range. In a preferred embodiment, the device is an external defibrillator.

Abstract: A method and circuit are described for automatically testing various components of a defibrillator at random or otherwise aperiodic time intervals. A random number is generated that falls within a range of numbers corresponding to minimum and maximum acceptable time intervals between successive testing of the defibrillator. Ambient conditions can be measured and the acceptable range of numbers adjusted accordingly. High energy test procedures may be performed less frequently, as appropriate for the measured ambient conditions. The range of numbers can also be adjusted to provide greater frequency testing where desirable, such as following a use of the defibrillator, following a repair of the defibrillator, to detect infant mortality effects, or to detect wear-out effects. The defibrillator includes a testing circuit for testing the various other components. The testing circuit includes a controller coupled with a timer, a random number generator, a memory, and an ambient condition sensor.

Abstract: A method of maintaining an electronic device, the method including the steps of monitoring ambient an environmental condition such as temperature or humidity; monitoring a self-test initialization criterion; performing an automatic device self-test if the self-test criterion is met and if the environmental condition is within a predetermined range; and not performing the automatic device self-test if the self-test criterion is met but the environmental condition is outside the predetermined range. In a preferred embodiment, the device is an external defibrillator.

Abstract: An intelligent battery having an advance low battery warning for a battery powered device is provided. The intelligent battery comprises a battery suitable for powering a battery powered device and a charge monitor circuit. The charge monitor circuit continuously measures the amount of electrical charge input and output from the battery. When the amount of charge remaining in the battery goes below a threshold amount, an advance low battery warning is generated, wherein the charge remaining in the battery is calculated by subtracting the amount of electrical charge output from the battery from the amount of electrical charge input into the battery. The low battery warning occurs independently of the output voltage of the battery such that an advance low battery warning may be provided for a battery that maintains a substantially constant output voltage until just prior to complete discharge.

Abstract: A system having a battery, a battery support unit, and an electronic device provides for the exchange of information between the battery support unit and the electronic device via a mailbox in memory in the battery. When the battery is placed in the battery support unit, the battery support unit tests the battery for an error condition. If the battery support unit finds an error condition with the battery, it transmits error data to a mailbox located in the battery's memory. When the battery is then removed from the battery support unit and placed in an electronic device, the electronic device can read the error data in the mailbox and take an appropriate action. For example, the electronic device reads the mailbox and find the error data placed there by the battery support unit. In response to finding this error data, the electronic device enables an indicator, such as an indicator that informs a user that maintenance needs to be performed on the battery.

Abstract: An ECG recorder and playback unit which includes software-implemented digital signal processing filters which compensate for phase and magnitude distortion occurring when an ECG signal is recorded on a Holter recorder and played back. This permits "tuning" a recorder and playback unit which may be unrelated, as when made by different manufacturers. An impulse or step signal is recorded and played back to provide a system frequency response measurement. Coefficients for a digital correction filter are derived from the discrete Fourier transform of the impulse or step response and a desired system response. When recorded ECG data is played back, it is filtered on a substantially real-time basis with the digital correction filter to compensate for phase and magnitude distortion. Prior to recording, the high frequencies of the ECG signal are boosted to compensate for high frequency losses inherent in the recording and playing back of ECG signals.

Abstract: The method and system for precise time based presentation of recorded medical data, such as cardiac data, encephalographic data, fetal monitor data or the like, which has been recorded on an ordinary audio cassette tape utilizing an inexpensive presentation device. An off-the-shelf tape transport deck is utilized which operates at an actual presentation speed which varies in a linear fashion in response to variations of a control signal which do not vary by greater than a selected maximum value during a given time period and in a nonlinear fashion in response to variations of a control signal which do vary by greater than the selected maximum value during a given time period. A timing track signal is utilized to determine actual presentation speed and small variations between the desired presentation speed and the actual presentation speed are coupled to a linear control system and utilized to vary the control signal at a rate which does not exceed a first rate.

Abstract: An ECG waveform calibration method combines ECG channel calibration pulses to form combined calibration pulses. The combined channel pulses are filtered to select valid combined pulses. The selected combined pulses are correlated to the corresponding channel calibration pulses to determine valid channel calibration pulses from which a correction scale factor is derived. A valid calibration pulse is determined where a correlation between a combined calibration pulse and a corresponding channel calibration pulse is greater than a predetermined correlation value. The valid channel calibration pulses are then characterized. A set of valid channel calibration pulses is selected for each channel based on the characterization to form an average calibration pulse. The average calibration pulse is used to determine a correction scale factor for each channel which is used to scale the actual channel ECG waveform data. The method also includes a step for adjusting the intra-channel skew.

Abstract: An ECG recorder and playback unit which includes software-implemented digital signal processing filters which compensate for phase and magnitude distortion occurring when an ECG signal is recorded on a Holter recorder and played back. This permits "tuning" a recorder and playback unit which may be unrelated, as when made by different manufacturers. An impulse or step signal is recorded and played back to provide a system frequency response measurement. Coefficients for a digital correction filter are derived from the discrete Fourier transform of the impulse or step response and a desired system response. When recorded ECG data is played back, it is filtered on a substantially real-time basis with the digital correction filter to compensate for phase and magnitude distortion. Prior to recording, the high frequencies of the ECG signal are boosted to compensate for high frequency losses inherent in the recording and playing back of ECG signals.

Abstract: An ECG waveform calibration method combines ECG channel calibration pulses to form combined calibration pulses. The combined channel pulses are filtered to select valid combined pulses. The selected combined pulses are correlated to the corresponding channel calibration pulses to determine valid channel calibration pulses from which a correction scale factor is derived. A valid calibration pulse is determined where a correlation between a combined calibration pulse and a corresponding channel calibration pulse is greater than a predetermined correlation value. The valid channel calibration pulses are then characterized. A set of valid channel calibration pulses is selected for each channel based on the characterization to form an average calibration pulse. The average calibration pulse is used to determine a correction scale factor for each channel which is used to scale the actual channel ECG waveform data. The method also includes a step for adjusting the intra-channel skew.