Abstract: A portable sleep monitoring system for recording on tape, transcribing and charting a plurality of physiologic data channels recorded relative to a known constant, user-transparent time base. Selected ECG, air flow, impedance and pulse oximetry sensor inputs are recorded under microprocessor control relative to a crystal controlled 40 Hz signal modulated with the physiologic data from one of the sensors. Upon reading the physiologic data from tape and/or charting, the collected data is displayed with the time base, normalized to the known crystal controlled timing signal. In the heart rate mode, QRS occurences are displayed on the heart rate trace line as singular hash marks. The presence of motion at the pulse O2 sensor is indicated by multiplexing high frequency hash markings onto the O2 saturation trace line. Calibration levels relating to four different O2 saturation percent vales are periodically written to tape for reference during tape reading.

Abstract: Circuitry for the validation of repetitive signals including input/output circuitry providing information regarding signals received that is connected to a progammable microprocessor, a read only memory and random access memory. The microprocessor is programmed so the circuitry determines the receipt of an input signal at any one of several signal inputs. When a first signal is received at one of the signal inputs a "lock-out" time interval is provided during which another signal cannot be received at any signal input. This is followed by a "window" time interval during which another input signal can be received at the signal input receiving the first signal. A "lock-out" and a "window" time interval are provided for each signal received at the signal input during a "window" time period at which the first input signal was received. Such signals are counted until a predetermined count is reached thereby establishing the received signals as valid signals.