Abstract: A system for encoding, recording, playing back, decoding, validating, and displaying cardiac signals obtained from a patient during ambulatory monitoring. The system permits the recording on a single track in a magnetic tape of a channel of ECG signals interrupted intermittently by blood pressure signals, time of day signals, and event marker signals. The ECG signal is recorded in analog form, but the other signals are recorded as pulse coded signals each having its own format. In the playback apparatus, decoders identify and verify each of the signals when they occur, and the played back information is plotted on a chart. If the time of day signal was not recorded on the tape, timing information can be produced by the playback apparatus from the cumulative tape travel. Fiducial signals introduced in the recording, playback, and charting operations are used in a method for identification and measurement of recording tape speed error, playback tape error, and plotter speed error.

Abstract: Apparatus under control of an operator for selectively displaying signals stored on a magnetic tape. The tape is normally first played back at a high speed, with the reproduced signal displayed at high speed to permit the operator to determine which parts of the tape to view at real-time speed. In the real-time viewing mode, a segment of the tape is played again at high speed to provide a better quality signal; the signal from the segment is converted to digital form and stored in a memory for use in creating a real-time display. The operator then can view the display of the stored signal in a variety of ways: stationary, advancing at real-time speed, or in reverse at real-time speed. The length of the segment stored is relatively short to minimize the size of the memory. After a segment is played back, the tape is brought to a stop and then moved in the opposite direction to position it for playing back the next segment.

Abstract: A high performance magnetic tape transport and tape cartridge. The cartridge includes coplanar hubs carrying tape rolls rotatable about fixed axes. The transport includes a pair of capstans, each mounted on its own carriage assembly with its own drive motor. The capstans have a high friction surface. The carriage assemblies are spring biased with equal force toward the front of the cartridge. When the cartridge is inserted in the transport, the capstans drivingly engage the peripheries of the tape rolls, and magnetic transducer heads in the transport engage the front face of a span of tape between the rolls. The capstan motors are driven by a servo control system. The servo system provides fully bi-directional operation, highly accurate speed control, and unprecedented tension control, both across the transducer head and in the takeup roll.