19-34. The AN/PRC-90 survival radio is a part of the Army aviator's survival vest. The AN/PRC-112 will eventually replace the AN/PRC-90. Both radios can transmit either tone or voice. Any other type of Army radio can do the same. The ranges of the different radios vary depending on the altitude of the receiving aircraft, terrain, vegetation density, weather, battery strength, type of radio, and interference. To obtain maximum performance from radios, use the following procedures:
Try to transmit only in clear, unobstructed terrain. Since radios are line-of-sight communications devices, any terrain between the radio and the receiver will block the signal.
Keep the antenna at right angles to the rescuing aircraft. There is little or no signal strength emanating from the tip of the antenna.
If the radio has tone capability, place it upright on a flat, elevated surface so that you can perform other survival tasks.
Never let any part of the antenna or its mounting lug touch your clothing, body, foliage, or the ground. Such contact greatly reduces the range of the signal.
Conserve battery power. Turn the radio off when you are not using it. Do not transmit or receive constantly. In hostile territory, keep transmissions short to avoid enemy radio direction finding.
In cold weather, keep the battery inside your clothing when not using the radio. Cold quickly drains the battery's power. Do not expose the battery to extreme heat such as desert sun. High heat may cause the battery to explode. The radio is designed to be waterproof, but always try to keep the radio and battery as dry as possible, as water may destroy the circuitry.
A worldwide satellite monitoring system has been developed by international search and rescue agencies to assist in locating survivors. To activate this search and rescue satellite-aided tracking (SARSAT) system in peacetime, key the transmitter for a minimum of 30 seconds.