DSA Operational Parameters with Wireless Microphones

The effect of man-made noise in wireless microphone operation has been studied in this paper. Man-made noise measurements were taken in different locations in Vienna, VA and the amount of interference from man-made noise in potential wireless microphone channels were analyzed. Data collection results show that man-made noise levels can be up to 30 dB above the thermal noise floor. Our results show that wireless microphones have to have a high signal-to-noise ratio in order to cope with the adverse effects of high man-made noise levels (>60 dB). Furthermore, wireless microphone path loss measurements were conducted in Vienna, VA to determine the required exclusion distance for DSA devices to ensure reliable wireless microphone operation. The results show that the required exclusion zone can be safely and conservatively set at around 130 m when the results from man-made noise measurements and wireless microphone propagation measurements are used. Shared Spectrum Company also worked on a wireless microphone simulation to determine the required sensing threshold levels for impairment-free wireless microphone operation. An indoor-to-outdoor path loss model was created based on the wireless microphone path loss measurement results. This statistical path loss model was used to determine the received signal level at DSA devices and wireless microphone receiver (interference level). Our results show that the required sensing threshold can be set at around -110 dBm (in a 110 kHz channel) when man-made noise and representative propagation models are used.