Abstract: Precise amplitude and phase measurement of a narrowband signal is required in many practical applications related to underwater sensing, navigation, and positioning. In this paper, we propose a novel method for digital signal acquisition based on multiple signal sampling. This method is an extension of quadrature sampling where amplitude and phase of a harmonic signal can be obtained based on only two samples taken within one period. The advantage of our generalization are reduced errors caused by quantization noise of A/D converters.