Experimental conditions for high fidelity electron spectroscopy are discussed when digitized sweep generator is used to drive spectrometer with lock-in signal detection and computerized data acquisition/processing. Spectral quality were evaluated in terms of signal to noise ratio (S/N ratio) and full width at the half-maximum (FWHM) in N(E) mode or energy separation of peak maxima in differential mode. Optimums of following terms were discussed from points of noise reduction ability and due time for measurement: (1) nature of noise signal; (2) sweep mode and repeat times of measurement; (3) parameters of the lock-in amplifier and scanning speed; (4) numerical treatment on spectral data.