Ultrasound independent Advisory Group on Non-ionising Radiation (AGNIR) produced a report in 2010, which was published by the UK Health Protection Agency (HPA). This report recommended an exposure limit for the general public to airborne ultrasound sound pressure levels (SPL) of 70 dB (at 20 kHz), and 100 dB (at 25 kHz and above). Ultrasound Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies from person to person and is approximately 20 kilohertz (20,000
Multi-Use Radio Service issued for MURS within the United States. MURS comprises the following five frequencies: Channels 1–3 must use "narrowband" frequency modulation (2.5 kHz deviation). Channels 4 and 5 may use either "wideband" FM (5 kHz deviation) or "narrowband" FM. MURS falls under part 95 and was not mandated for narrow-banding, such as those of Part 90 in the public service bands by January 2013. Because previous business band licensees who have maintained their active license remain grandfathered with their existing operating privileges, it is possible to find repeaters or other operations not authorized by Part 95 taking place. These are not