frequency-domain measurements
71Schumann resonances — The Schumann resonances (SR) are a set of spectrum peaks in the extremely low frequency (ELF) portion of the Earth s electromagnetic field spectrum. Schumann resonances are global electromagnetic resonances, excited by lightning discharges in the …
72A-weighting — A graph of the A , B , C and D weightings across the frequency range 10 Hz – 20 kHz Video illustrating A weighting by analyzing a sine sweep (contains audio) A weighting is the most …
73Crystal — /kris tl/, n. 1. a city in SE Minnesota, near Minneapolis. 25,543. 2. a female given name. * * * I Any solid material whose atoms are arranged in a definite pattern and whose surface regularity reflects its internal symmetry. Each of a crystal s… …
74Mathematics and Physical Sciences — ▪ 2003 Introduction Mathematics Mathematics in 2002 was marked by two discoveries in number theory. The first may have practical implications; the second satisfied a 150 year old curiosity. Computer scientist Manindra Agrawal of the… …
75probability theory — Math., Statistics. the theory of analyzing and making statements concerning the probability of the occurrence of uncertain events. Cf. probability (def. 4). [1830 40] * * * Branch of mathematics that deals with analysis of random events.… …
76Electromagnetic reverberation chamber — A look inside the (large) Reverberation Chamber at the Otto von Guericke University Magdeburg, Germany. On the left side is the vertical Mode Stirrer (or Tuner), that changes the electromagnetic boundaries to ensure a (statistically) homogeneous… …
77Magnetometer — A magnetometer is a measuring instrument used to measure the strength or direction of a magnetic field either produced in the laboratory or existing in nature. Some countries such as the USA, Canada and Australia classify the more sensitive… …
78History of radar — The history of radar starts with experiments by Heinrich Hertz in the late 19th century that showed that radio waves were reflected by metallic objects. This possibility was suggested in James Clerk Maxwell s seminal work on electromagnetism.… …
79Magnetotellurics — Magnetotelluric station Magnetotellurics (MT) is an electromagnetic geophysical method of imaging the earth s subsurface by measuring natural variations of electrical and magnetic fields at the Earth s surface. Investigation depth ranges from… …
80Measuring receiver — In telecommunication, a measuring receiver or measurement receiver is a calibrated laboratory grade radio receiver designed to measure the characteristics of radio signals. The parameters of such receivers (tuning frequency, receiving bandwidth,… …
