Seismic instruments: article

Аnnotation: The principles and techniques used to detect signals propagating in the atmosphere in the infrasonic frequency band are described. Such signals can be generated by various sources: ground and air explosions, objects moving with supersonic speed in the atmosphere (aircrafts, rockets, fireballs, fragments of spent stages of carrier rockets). A description is given of portable infrasound monitoring stations, each of which includes 3 infrasonic microphones spaced apart from each other. Each such station makes it possible to determine three basic parameters of an infrasonic signal, which are subsequently used to solve the location problem: arrival time of the infrasonic wave, backazimuth to the source and the angle between wave vector and day surface. A description is given of an acoustic detector used to extract useful signals against a noise background. The detector is based on an algorithm similar to the detection algorithm STA/LTA known in seismology. Examples of the operation of the acoustic detector with data obtained during real measurements are given. The technology of passive infrasound location is described, which is based on mathematical modeling of propagation of infrasonic waves, generated by objects moving along possible trajectories, comparing these theoretical signals with real ones, registered by monitoring stations, and determination of realized trajectories. Examples of experimental confirmation of the passive infrasound location technology effectiveness for determining the places of fragments of 1 and 2 stages of carrier rockets fall are given. It is shown that use of the systems of infrasound location allows to reduce the estimated area of search for the fallen fragments of launch vehicles, significantly reduce the time and cost or their search and utilization, and thus, to reduce the level of the negative impact of the rocket and space industry on the environment.