Abstract: Circuitry for quantitatively determining the level of processed heart signals relative to actual sensing sensitivity level (threshold) in an implantable pacemaker. The measurement is useful for adjusting the settable threshold, polarity, filtering or amplification parameter settings for safe operation and noise rejection of the pacemaker.

Abstract: The exemplary embodiment comprising a signal reception part and a routing device which routes specific signal information for storage to information memories provided for that purpose. The goal of the disclosure is to create such a signal processing means which, given the lowest possible circuit-technical outlay, always prevents an undesired re-programming of information memories with absolute certainty. This goal is inventively achieved in that a locking register is allocated to a memory bank constructed of a plurality of information memories, in which locking register a locking signal can be inscribed for each information memory which is specifically allocated to this information memory, on the basis of which locking signal a change of the stored informational content is made impossible as long as no opening signal for an appertaining information memory is input into the locking register from the outside.