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A compass is a device that shows the cardinal directions used for navigation and geographic orientation. It commonly consists of a magnetized needle or other element, such as a compass card or compass rose, which can pivot to align itself with magnetic north. Other methods may be used, including gyroscopes, magnetometers, and GPS receivers.
A gyroscope is a device used for measuring or maintaining orientation and angular velocity. It is a spinning wheel or disc in which the axis of rotation is free to assume any orientation by itself. When rotating, the orientation of this axis is unaffected by tilting or rotation of the mounting, according to the conservation of angular momentum.
A gyrocompass is a type of non-magnetic compass which is based on a fast-spinning disc and the rotation of the Earth to find geographical direction automatically. A gyrocompass makes use of one of the seven fundamental ways to determine the heading of a vehicle. A gyroscope is an essential component of a gyrocompass, but they are different devices; a gyrocompass is built to use the effect of gyroscopic precession, which is a distinctive aspect of the general gyroscopic effect. Gyrocompasses, such as the fibre optic gyrocompass are widely used to provide a heading for navigation on ship's. This is because they have two significant advantages over magnetic compasses:
The Raytheon Company was a major U.S. defense contractor and industrial corporation with manufacturing concentrations in weapons and military and commercial electronics. It was previously involved in corporate and special-mission aircraft until early 2007. Raytheon was the world's largest producer of guided missiles. In April 2020, the company merged with United Technologies Corporation to form Raytheon Technologies, which, since July 2023, is known as RTX Corporation.
A ring laser gyroscope (RLG) consists of a ring laser having two independent counter-propagating resonant modes over the same path; the difference in phase is used to detect rotation. It operates on the principle of the Sagnac effect which shifts the nulls of the internal standing wave pattern in response to angular rotation. Interference between the counter-propagating beams, observed externally, results in motion of the standing wave pattern, and thus indicates rotation.
Elmer Ambrose Sperry Sr. was an American inventor and entrepreneur, most famous for construction, two years after Hermann Anschütz-Kaempfe, of the gyrocompass and as founder of the Sperry Gyroscope Company. He was known as the "father of modern navigation technology".
The Sagnac effect, also called Sagnac interference, named after French physicist Georges Sagnac, is a phenomenon encountered in interferometry that is elicited by rotation. The Sagnac effect manifests itself in a setup called a ring interferometer or Sagnac interferometer. A beam of light is split and the two beams are made to follow the same path but in opposite directions. On return to the point of entry the two light beams are allowed to exit the ring and undergo interference. The relative phases of the two exiting beams, and thus the position of the interference fringes, are shifted according to the angular velocity of the apparatus. In other words, when the interferometer is at rest with respect to a nonrotating frame, the light takes the same amount of time to traverse the ring in either direction. However, when the interferometer system is spun, one beam of light has a longer path to travel than the other in order to complete one circuit of the mechanical frame, and so takes longer, resulting in a phase difference between the two beams. Georges Sagnac set up this experiment in 1913 in an attempt to prove the existence of the aether that Einstein's theory of special relativity makes superfluous.
An autonomous underwater vehicle (AUV) is a robot that travels underwater without requiring continuous input from an operator. AUVs constitute part of a larger group of undersea systems known as unmanned underwater vehicles, a classification that includes non-autonomous remotely operated underwater vehicles (ROVs) – controlled and powered from the surface by an operator/pilot via an umbilical or using remote control. In military applications an AUV is more often referred to as an unmanned undersea vehicle (UUV). Underwater gliders are a subclass of AUVs.
Navigational instruments are instruments used by nautical navigators and pilots as tools of their trade. The purpose of navigation is to ascertain the present position and to determine the speed, direction, etc. to arrive at the port or point of destination.
A fibre-optic gyroscope (FOG) senses changes in orientation using the Sagnac effect, thus performing the function of a mechanical gyroscope. However its principle of operation is instead based on the interference of light which has passed through a coil of optical fibre, which can be as long as 5 kilometres (3 mi).
Distributed temperature sensing systems (DTS) are optoelectronic devices which measure temperatures by means of optical fibres functioning as linear sensors. Temperatures are recorded along the optical sensor cable, thus not at points, but as a continuous profile. A high accuracy of temperature determination is achieved over great distances. Typically the DTS systems can locate the temperature to a spatial resolution of 1 m with accuracy to within ±1 °C at a resolution of 0.01 °C. Measurement distances of greater than 30 km can be monitored and some specialised systems can provide even tighter spatial resolutions. Thermal changes along the optical fibre cause a local variation in the refractive index, which in turn leads to the inelastic scattering of the light propagating through it. Heat is held in the form of molecular or lattice vibrations in the material. Molecular vibrations at high frequencies (10 THz) are responsible for Raman scattering. Low frequency vibrations (10–30 GHz) cause Brillouin scattering. Energy is exchanged between the light travelling through the fibre and the material itself and cause a frequency shift in the incident light. This frequency shift can then be used to measure temperature changes along the fibre.
A fiber-optic sensor is a sensor that uses optical fiber either as the sensing element, or as a means of relaying signals from a remote sensor to the electronics that process the signals. Fibers have many uses in remote sensing. Depending on the application, fiber may be used because of its small size, or because no electrical power is needed at the remote location, or because many sensors can be multiplexed along the length of a fiber by using light wavelength shift for each sensor, or by sensing the time delay as light passes along the fiber through each sensor. Time delay can be determined using a device such as an optical time-domain reflectometer and wavelength shift can be calculated using an instrument implementing optical frequency domain reflectometry.
Marine electronics refers to electronics devices designed and classed for use in the marine environment on board ships and yachts where even a small amount of salt water can destroy some electronics devices. Therefore, the majority of these types of devices are either water resistant or waterproof.
An inertial navigation system is a navigation device that uses motion sensors (accelerometers), rotation sensors (gyroscopes) and a computer to continuously calculate by dead reckoning the position, the orientation, and the velocity of a moving object without the need for external references. Often the inertial sensors are supplemented by a barometric altimeter and sometimes by magnetic sensors (magnetometers) and/or speed measuring devices. INSs are used on mobile robots and on vehicles such as ships, aircraft, submarines, guided missiles, and spacecraft. Older INS systems generally used an inertial platform as their mounting point to the vehicle and the terms are sometimes considered synonymous.
Future Fibre Technologies (FFT) is a fiber optic sensing technologies company based in Melbourne, Australia, with its US head office in Mountain View, California, Middle East head office in Dubai, Indian head office in New Delhi and European head office in London. Founded in 1994, Future Fibre Technologies product line provides optical fiber intrusion detection systems for perimeters, buried oil and gas pipelines and data communication networks.
Electronic compass can refer to:
The Hemispherical Resonator Gyroscope (HRG), also called wine-glass gyroscope or mushroom gyro, is a compact, low-noise, high-performance angular rate or rotation sensor. An HRG is made using a thin solid-state hemispherical shell, anchored by a thick stem. This shell is driven to a flexural resonance by electrostatic forces generated by electrodes which are deposited directly onto separate fused-quartz structures that surround the shell. The gyroscopic effect is obtained from the inertial property of the flexural standing waves. Although the HRG is a mechanical system, it has no moving parts, and can be very compact.
A HRG gyrocompass is a compass and instrument of navigation. It is the latest generation of maintenance-free instruments.
RTX Corporation, formerly Raytheon Technologies Corporation, is an American multinational aerospace and defense conglomerate headquartered in Arlington, Virginia. It is one of the largest aerospace and defense manufacturers in the world by revenue and market capitalization, as well as one of the largest providers of intelligence services. RTX manufactures aircraft engines, avionics, aerostructures, cybersecurity solutions, guided missiles, air defense systems, satellites, and drones. The company is also a large military contractor, getting a significant portion of its revenue from the U.S. government.
Anschütz is a company that produces marine navigation systems and related instruments. It formed as Anschütz & Company in 1905 in Kiel, Germany, in order to produce the first gyrocompass for large ships, which entered service in 1907. The company expanded to produce autopilots and new forms of compasses. The original company was broken up at the end of World War II.
References
- ↑ "Marine Fiber Optic and Spinning Mass Gyrocompasses". IEEE Xplore. 2020-11-06. Retrieved 2023-11-19.
- ↑ Pascoli, Gianni (2017). "The Sagnac effect and its interpretation by Paul Langevin". Comptes Rendus Physique. Cellule MathDoc/CEDRAM. 18 (9–10): 563–569. doi: 10.1016/j.crhy.2017.10.010 . ISSN 1631-0705.
- 1 2 Seamanship Techniques:Shipboard and Marine Operations, D. J. House, Butterworth-Heinemann, 2004, p. 341
- ↑ "Raytheon Anschütz launches Standard 30 MF Gyro Compass". www.raytheon-anschuetz.com. Retrieved 2018-12-21.[ permanent dead link ]