Abstract: A signal conditioner for use with cardiographic data and other biological signals includes a baseline shift circuit and a variable gain amplifier. A feedback loop is provided for the output signal with a reference which designates the maximum value of the output signal. Within the baseline shifting circuit, there is provided circuitry which compares the amount of offset of the negative excursions of the waveform from a reference lead so as to introduce a feedback compensation signal which shifts the baseline and thereby compensates for drift in the baseline. Integration circuitry in the form of counters of clock pulses are provided in the control of both amplifier gain and baseline shift. Timing circuitry provides for the interleaving of set-up intervals with data aquisition intervals, the gain adjustment and baseline adjustment being accomplished only during the set-up intervals.