Abstract

Optical microscopic analysis of honey is time consuming due to the period needed to prepare samples. Time reduction could be achieved with ultrasound microscopy. This paper investigates the behavior of 125 MHz signal modulated by 16-bits Golay code spread out through a honey sample containing pollen. A bipolar phase shift keying (BPSK) modulation of 125 MHz frequency by 16-bits Golay code was implemented in Simulink/Matlab environment. The frequency implemented was set up considering the acoustic properties of honey containing pollen, the thickness of the sample and the size of pollen. At this frequency, the evaluated attenuation coefficient of honey containing pollen was 0.135 dB/µm/MHZ(γ =1); it depends on the power factor γ related to the scattering medium, and the delay induces by the size of pollen. The impact of these parameters, added to 5dB White Gaussian Noise on 200 V magnitudes BPSK Golay sequences, decreased the autocorrelation function magnitude from 8×104 V to 1.5×104 V. The width (Wd) decreases from 4 ns at 0.135 dB/µm/MHz(γ =1) to 3.5 ns at 16.875 dB/µm/MHz(γ =2), when the Pulse Side lobe Level (PSL) increases from -22.79 dB at 1.509 dB/µm/MHz(γ =1) to -9.54 dB at 16.875 dB/µm/MHz(γ =2).

Key words: Ultrasound, honey, attenuation coefficient, Golay code, BPSK modulation, autocorrelation function.