Experimental and numerical analyses of wind-induced noise in two-way radios

Abstract

The generation of wind noise of entrance microphone cavities owing to turbulent airflow is an inherent problem with radio telecommunication systems, such as two-way radios. It will lead to a pressure fluctuation which is highly unpleasant and would degrade a two-way radio communication. This research aims to understand the relationship between noise level and the flow structure of the different parameters to the occurrence of noise during communication using a two-way radio device. A noise measurement is conducted to analyse the sound pressure level (SPL) within a cavity, in which computational fluid dynamic(CFD) is used to investigate the flow behaviour on the various effects of cavity positions at P1, P2, P3, P4, and P5 and wind velocities of 0.75 m/s, 1.49 m/s, 2.24 m/s, 2.99 m/s and 3.75 m/s which corresponding to Reynolds number (Re) of 8694, 17389, 26083, 34777, and 43471 respectively. CFD result showed the presence of separation of the shear layer, the development of vortex shedding, the recirculation region and vorticity were present inside the edges of the cavity. SPL increased with an increase in wind velocity and, the cavity distance of P4. In the cavity position of P5, SPL is decreased due to the wind velocity exceeding the maximum level of a wind tunnel. Therefore, the cavity position of P5 is suitable for reducing wind noise. These parameters are significant for improving the design of two-way radio to reduce the noise during outdoor communication.