The ITU Radiocommunication Assembly considering a)that service interruptions may be caused by natural and man-made phenomena, e.g. solar interference, interference from other systems, ignition noise, attenuation due to multipath or atmospheric effects, which adversely affect the wanted signal and in the case of digital transmission systems, result in bursts of errors;b)that use of appropriate techniques and inclusion of equipment redundancy, etc.,can improve service availability;c)that system parameters such as receive signal margins affect the link, and therefore system availability.