Abstract: Methods useful for differentiating and enumerating subpopulations of particles in a sample and more particularly relates to the enumeration of leukocyte subclasses. Enumeration is accomplished by utilizing two light scatter parameters and converting these parameters to a single parameter by employing a mathematical, nonlinear transformation.

Abstract: Input pulses are coupled through a delay network to a pulse amplifier. The amplifier includes feedback circuitry for correcting its output to a particular baseline level, generally zero volts. Within the amplifier feedback path is a gate, which is normally closed. Input pulses are also coupled to a pulse detector; whenever an input pulse is detected, the baseline gate in the amplifier feedback path is open, and the dynamic feedback operation is temporarily inhibited. During this time, the most recent previous level of baseline correction is retained.

Abstract: Signals including noise, platelet pulses, and red cell pulses are amplified and compared to a noise threshold. If larger than the threshold, the signals are integrated and the integrated signals are compared to respective red cell and platelet references.