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
General Mobile Radio Service and 25 kHz channel bandwidth although some "bubble pack" combo FRS/GMRS radios utilize 2.5 kHz deviation. For best compatibility of audio level, 5 kHz deviation should be used when communicating with GMRS equipment. The 4-digit decimal GMRS frequencies (shared FRS 1-7 / ICOM 9-15) are spaced 12.5 kHz from the (ICOM 1-8) GMRS frequencies, and may receive interference from other nearby stations. It may be advisable to use 12.5 kHz narrow-band (NFM) in congested areas, or avoid their use as a last resort. This second set of frequencies shows the interstitial ranges shared with the Family Radio Service services. These