Abstract: In a system for detecting information stored upon a flexible magnetic media that includes a magnetic transducer for producing an analog signal representing stored binary data, comparator means for detecting positive and negative peaks of the analog signal, and voltage threshold means for providing a reference threshold voltage to the comparator which is a precise percentage of the voltage peaks of the analog signal, an improved magnetic recording detection pointer comprising a pulse width discriminator used to monitor the time per peak during which the analog signal exceeds the detection threshold as an indication of marginal data which can be used in conjunction with an error correction system to extend the overall system correction capability.

Abstract: The signal indicative of switching of the ignition primary coil of a spark ignition engine is conditioned by means of compatible, combined, multiple and variable threshold testing of both the high end and the low end of the coil primary, without need to know (or alter operation in dependence upon) whether the engine employs positive switching at the high end of the primary coil or negative switching at the low end of the primary coil. To sense the end of the dwell period, the high coil voltage is compared against a negative voltage which will never occur if low coil switching is employed, but which will occur at the start of firing time in a positive switching system. Similarly, low coil is compared against a positive voltage which would never occur in a positively switched system, but which does occur at the start of firing time if negative switching is used.

Abstract: The end of the dwell period of a spark ignition engine is recognized by a high voltage, spark-creating swing in the low coil signal determined from comparison with a first, fixed threshold voltage which is above the current limited voltage variation of modern electronic high voltage ignition systems and a low peak primary voltage normally achieved with ignition defeat used in other diagnostic procedures. The beginning of the dwell period is sensed by comparing the low coil signal to the actual battery voltage of the engine under test; the comparison is against a substantial fraction of battery voltage which will always exceed any low coil voltage which could exist during the dwell period.