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A magnet, known as an AWS magnet is installed on the track center line. The magnetic field of the magnet is set based on the next signal aspect. [1] The train detects the polarity of magnetic field via an AWS receiver, permanently mounted under the train. [1] An AWS magnet is made up of 1 permanent magnet, and an optional electromagnet.
The magnetic detector or Marconi magnetic detector, sometimes called the "Maggie", was an early radio wave detector used in some of the first radio receivers to receive Morse code messages during the wireless telegraphy era around the turn of the 20th century.
The detector houses magnets incorporated into an electric circuit. Magnetic lines of force attract ferrous particles. Collection of these particles continues until the insulated air gap between the magnets (two magnet configuration) or between the magnet and housing (one magnet configuration) is bridged, effectively closing the circuit.
A magnetic anomaly detector (MAD) is an instrument used to detect minute variations in the Earth's magnetic field. [1] The term typically refers to magnetometers used by military forces to detect submarines (a mass of ferromagnetic material creates a detectable disturbance in the magnetic field ).
It remains likely that two or more complementary mechanisms play a role in magnetic field detection in animals. Of course, this potential dual mechanism theory raises the questions of to what degree each method is responsible for the stimulus, and how they produce a signal in response to the weak magnetic field of the Earth.
The magnets are mounted between the brushes and tool body to create a magnetic circuit along the pipe wall. As the tool travels along the pipe, the sensors detect interruptions in the magnetic circuit. Interruptions are typically caused by metal loss, which is typically caused by corrosion and is denoted as a "feature".
A MEMS magnetic field sensor is a small-scale microelectromechanical systems (MEMS) device for detecting and measuring magnetic fields (magnetometer). Many of these operate by detecting effects of the Lorentz force : a change in voltage or resonant frequency may be measured electronically, or a mechanical displacement may be measured optically.
The most common type was the so-called cat's whisker detector, which consisted of a piece of crystalline mineral, usually galena (lead sulfide), with a fine wire touching its surface. [1] [4] [5] The "asymmetric conduction" of electric current across electrical contacts between a crystal and a metal was discovered in 1874 by Karl Ferdinand ...