continuous wave

Amplitude-shift keying (ASK) is a form of modulation which represents digital data as variations in the amplitude of a carrier wave. Amplitude-shift keying - Encoding. The simplest and most common form of ASK operates as a switch, using the presence of a carrier wave to indicate a binary one and its absence to indicate a binary zero. This type of modulation is called on-off keying, and is used at radio frequencies to transmit Morse code (referred to as continuous wave operation). More s ...

Including:

• Amplitude-shift keying - Encoding
• Amplitude-shift keying - Probability of error
• Amplitude-shift keying - Considerations

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Amplitude modulation (AM) is a form of modulation in which the amplitude of a carrier wave is varied in direct proportion to that of a modulating signal. (Contrast this with frequency modulation, in which the frequency of the carrier is varied; and phase modulation, in which the phase is varied.) AM is commonly used at radio frequencies and was the first method used to broadcast commercial radio. The term "AM" is sometimes used generically to refer to the AM broadcast (mediumwave) band (see AM radio). Ampli ...

Including:

• Amplitude modulation - Applications in radio
• Amplitude modulation - AM vs. FM
• Amplitude modulation - Forms of AM
• Amplitude modulation - Example
• Amplitude modulation - A more general example
• Amplitude modulation - Modulation index
• Amplitude modulation - Amplitude modulator designs
• Amplitude modulation - Circuits
• Amplitude modulation - Low level
• Amplitude modulation - High level

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At the start of World War II both the United Kingdom and Nazi Germany knew of each other's ongoing efforts in their "battle of the beams". Both nations were intensely interested in the other's developments in the field, and engaged in an active campaign of espionage and false leaks about their respective equipment. But it was only in Britain that the usefulness of the system became obvious, so while the German systems had the edge technologically (operating on much shorter wavelengths) only Britain started true mass deployment of both the radar ...

See also:

History of radar, History of radar - Before the twentieth century, History of radar - 1900s, History of radar - Christian Huelsmeyer, History of radar - Nikola Tesla, History of radar - Naval Research Laboratory, History of radar - Robert Watson-Watt, History of radar - Hans Hollmann, History of radar - World War II, History of radar - UK, History of radar - Germany, History of radar - US, History of radar - Cold War

Read more here: » History of radar: Encyclopedia II - History of radar - World War II

A laser is composed of an active laser medium and a resonant optical cavity. The gain medium is a material of controlled purity, size, and shape, which uses a quantum mechanical effect called stimulated emission (discovered by Einstein while researching the photoelectric effect) to amplify the beam. For a laser to operate, the gain medium must be "pumped" by an external energy source, such as electricity or light (from a classical source such as a flash lamp, or another laser). The pump energy is absorbed by the laser medium to produc ...

See also:

Laser, Laser - Physics, Laser - History, Laser - Recent innovations, Laser - Uses of lasers, Laser - Popular misconceptions, Laser - LASER, Laser - Scientific misconceptions, Laser - Laser safety, Laser - Common laser types, Laser - Publications about lasers, Laser - Books, Laser - Periodicals

Read more here: » Laser: Encyclopedia II - Laser - Physics

Tesla coil - Transmission. A large Tesla coil of more modern design can operate at very high peak power levels, up to many megawatts (a million watts; hundreds of thousands of horsepower). It should therefore be adjusted and operated carefully, not only for efficiency and economy, but also for safety. If, due to improper tuning, the maximum voltage point occurs below the terminal, along the secondary coil, a discharge (spark), or possibly a ball of plasma, may break out and damage or destroy the coil wir ...

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Tesla coil, Tesla coil - History, Tesla coil - Early coils, Tesla coil - Disruptive Tesla coils, Tesla coil - Later coils, Tesla coil - Description, Tesla coil - Utilization and production, Tesla coil - Transmission, Tesla coil - Safety and precautions, Tesla coil - Air discharges, Tesla coil - Reception, Tesla coil - The skin effect myth, Tesla coil - Instances and devices, Tesla coil - Popularity, Tesla coil - Related Tesla patents, Tesla coil - Further reading and other references

Read more here: » Tesla coil: Encyclopedia II - Tesla coil - Utilization and production

Because CO2 lasers operate in the infrared, special materials are necessary for their construction. Typically, the mirrors are made of coated silicon, molybdenum, or gold, while windows and lenses are made of either germanium or zinc selenide. For high power applications, gold mirrors and zinc selenide windows and lenses are preferred. The most basic form of a CO2 laser consists of a gas discharge (with a mix close to that specified above) with a total reflector at one end, and an output coupler (usually a semi-r ...

See also:

Carbon dioxide laser, Carbon dioxide laser - Amplification, Carbon dioxide laser - Construction, Carbon dioxide laser - Applications

Read more here: » Carbon dioxide laser: Encyclopedia II - Carbon dioxide laser - Construction

Sometimes known as quaternary or quadriphase PSK or 4-PSK, QPSK uses four points on the constellation diagram, equispaced around a circle. With four phases, QPSK can encode two bits per symbol, shown in the diagram with Gray coding to minimize the BER — twice the rate of BPSK. Analysis shows that this may be used either to double the data rate compared to a BPSK system while maintaining the bandwidth of the si ...

See also:

Phase-shift keying, Phase-shift keying - Introduction, Phase-shift keying - Ideal structure, Phase-shift keying - Transmitter, Phase-shift keying - Receiver, Phase-shift keying - Definitions, Phase-shift keying - Applications, Phase-shift keying - Binary Phase-shift Keying BPSK, Phase-shift keying - Implementation, Phase-shift keying - Quadrature Phase-shift Keying QPSK, Phase-shift keying - Implementation, Phase-shift keying - QPSK signal in the time domain, Phase-shift keying - Offset QPSK OQPSK, Phase-shift keying - π / 4–QPSK, Phase-shift keying - Higher-order PSK, Phase-shift keying - Differential Encoding, Phase-shift keying - Example: Differentially encoded BPSK, Phase-shift keying - Differential Phase-shift Keying DPSK, Phase-shift keying - Notes

Read more here: » Phase-shift keying: Encyclopedia II - Phase-shift keying - Quadrature Phase-shift Keying QPSK

The Alexanderson alternator operates by variable reluctance, changing the magnetic flux linking two coils. The alternator has a circular laminated iron stator carrying two sets of coils, in a C-shape. One set of coils is energized with direct current and produces a magnetic field in the air gap. The second set of coils generates the radio-frequency voltage. The rotor is a laminated iron disk with holes or slots cut into its circumferance. The openings ...

See also:

Alexanderson alternator, Alexanderson alternator - Theory of Operation

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The simplest and most common form of ASK operates as a switch, using the presence of a carrier wave to indicate a binary one and its absence to indicate a binary zero. This type of modulation is called on-off keying, and is used at radio frequencies to transmit Morse code (referred to as continuous wave operation). More sophisticated encoding schemes have been developed which represent data in groups using additional amplitude levels. For instance, a four-level encoding scheme can represent two bits with each shift in amplitude ...

See also:

Amplitude-shift keying, Amplitude-shift keying - Encoding, Amplitude-shift keying - Probability of error, Amplitude-shift keying - Considerations

Read more here: » Amplitude-shift keying: Encyclopedia II - Amplitude-shift keying - Encoding

The invention of the device is credited to David Edward Hughes, among others. Oliver Joseph Lodge, in his Royal Institute lectures ("The Work of Hertz and Some of His Successors") coined the term "coherer" and gained the "syntonic" (or tuning) patent from the United States Patent Office. In 1892, Edouard Branly invented a coherer (which was named after him). Also, Alexander Popov developed a device similar to the "Branly coherer" to ...

See also:

Coherer, Coherer - History, Coherer - Description

Read more here: » Coherer: Encyclopedia II - Coherer - History

Any form of digital modulation necessarily uses a finite number of distinct signals to represent digital data. In the case of PSK, a finite number of phases are used. In the case of FSK, a finite number of frequencies are used. In the case of ASK, a finite number of amplitudes are used. This is very similar to pulse code modulation Each of these phases, frequencies or amplitudes are assigned a unique pattern of binary bits. Usually, each phase, frequency or amplitude encodes an equal number of bits. This number of bits comprises th ...

See also:

Modulation, Modulation - Analog modulation techniques, Modulation - Digital modulation techniques, Modulation - Pulse modulation, Modulation - Miscellaneous techniques

Read more here: » Modulation: Encyclopedia II - Modulation - Digital modulation techniques

Optical fiber is the most common type of channel for optical communications, however other types of optical waveguides are used within communications gear, and have even formed the channel of very short distance (e.g. chip-to-chip) links in laboratory trials. The transmitters in optical fiber links are generally light-emitting diodes (LEDs) or laser diodes. Infrared light, rather than visible light is used more commonly, because optical fibers transmit infrared wavelengths with less attenuation and dispersion. LEDs are generally restricted t ...

See also:

Optical communication, Optical communication - Forms of optical communication, Optical communication - Optical fiber communication, Optical communication - Free-space optical communication

Read more here: » Optical communication: Encyclopedia II - Optical communication - Optical fiber communication

A laser is composed of an active laser medium and a resonant optical cavity. The gain medium is a material of controlled purity, size, and shape, which uses a quantum mechanical effect called stimulated emission (discovered by Einstein while researching the photoelectric effect) to amplify the beam. For a laser to operate, the gain medium must be "pumped" by an external energy source, such as electricity or light (from a classical source such as a flash lamp, or another laser). The pump energy is absorbed by the laser medium to produc ...

See also:

Laser, Laser - Physics, Laser - History, Laser - Recent innovations, Laser - Uses of lasers, Laser - Popular misconceptions, Laser - Laser safety, Laser - Common laser types, Laser - Publications about lasers, Laser - Books, Laser - Journals

Read more here: » Laser: Encyclopedia II - Laser - Physics

Suppose we wish to modulate a simple sine wave on a carrier wave. The equation for the carrier wave of frequency ωc, taking its phase to be a reference phase of zero, is c(t) = Csin(ωct). The equation for the simple sine wave of frequency ωm (the signal we wish to broadcast) is m(t) = Msin(ω ...

See also:

Amplitude modulation, Amplitude modulation - Applications in radio, Amplitude modulation - AM vs. FM, Amplitude modulation - Forms of AM, Amplitude modulation - Example, Amplitude modulation - A more general example, Amplitude modulation - Modulation index, Amplitude modulation - Amplitude modulator designs, Amplitude modulation - Circuits, Amplitude modulation - Low level, Amplitude modulation - High level

Read more here: » Amplitude modulation: Encyclopedia II - Amplitude modulation - Example

This is a list of all radars known to be associated with the original S-300P system and all subsequent upgrades. Explanations of which radars perform which task for each version will follow: Target tracking: 5N63 Flap Lid A or 30N6/30N6E Flap Lid B I/J band target tracking and guidance phased-array radar (range 200 km/124 mile) 30N6E1 or 30N6E2 Tomb Stone I/J band target tracking radar (range 300 km/186 mile) Surveillance: 64N6 Big Bird F band or 64N6E/E2 Big Bird C band target acq ...

See also:

SA-10 Grumble, SA-10 Grumble - Variations, SA-10 Grumble - Guidance and warhead, SA-10 Grumble - History and upgrades, SA-10 Grumble - Radar, SA-10 Grumble - Users and other versions

Read more here: » SA-10 Grumble: Encyclopedia II - SA-10 Grumble - Radar

The active laser medium (laser gain/amplification medium) is a gas discharge which is air cooled (water cooled in higher power applications). The filling gas within the discharge tube consists primarily of: Carbon dioxide (CO2) (around 10-20 %) CO2 is a molecule with 3 atoms, the middle atom is carbon. Nitrogen (N2) (around 10-20%) Hydrogen (H2) and/or (Xe) (a few percent) Helium (He) (The remainder of the gas mixture) The specif ...

See also:

Carbon dioxide laser, Carbon dioxide laser - Amplification, Carbon dioxide laser - Construction, Carbon dioxide laser - Applications

Read more here: » Carbon dioxide laser: Encyclopedia II - Carbon dioxide laser - Amplification

Missiles are guided by the Flap Lid A or naval Top Dome system using command guidance with terminal semi-active radar homing. Later versions use the Flap Lid B or naval Tomb Stone radars to guide the missiles via command guidance/track-via-missile (TVM). The earlier Flap Lid A can guide up to four missiles at a time to up to four targets, and can track up to 24 targets at once. The Flap Lid B' can guide up to two missiles per target to up to six targets simultaneously. Targets flying at up to Mach 2.5 can be successfully engaged or around Ma ...

See also:

SA-10 Grumble, SA-10 Grumble - Variations, SA-10 Grumble - Guidance and warhead, SA-10 Grumble - History and upgrades, SA-10 Grumble - Radar, SA-10 Grumble - Users and other versions

Read more here: » SA-10 Grumble: Encyclopedia II - SA-10 Grumble - Guidance and warhead

For a signal that has been differentially encoded, there is an obvious alternative method of demodulation. Instead of demodulating as usual and ignoring carrier-phase ambiguity, the phase between two successive received symbols is compared and used to determine what the data must have been. When differential encoding is used in this manner, the scheme is known as differential phase-shift keying (DPSK). Note that this is subtly different to just differentially-encoded PSK since, upon reception, the received symbols are not decoded one-by-on ...

See also:

Phase-shift keying, Phase-shift keying - Introduction, Phase-shift keying - Ideal structure, Phase-shift keying - Transmitter, Phase-shift keying - Receiver, Phase-shift keying - Definitions, Phase-shift keying - Applications, Phase-shift keying - Binary Phase-shift Keying BPSK, Phase-shift keying - Implementation, Phase-shift keying - Quadrature Phase-shift Keying QPSK, Phase-shift keying - Implementation, Phase-shift keying - QPSK signal in the time domain, Phase-shift keying - Offset QPSK OQPSK, Phase-shift keying - π / 4–QPSK, Phase-shift keying - Higher-order PSK, Phase-shift keying - Differential Encoding, Phase-shift keying - Example: Differentially encoded BPSK, Phase-shift keying - Differential Phase-shift Keying DPSK, Phase-shift keying - Notes

Read more here: » Phase-shift keying: Encyclopedia II - Phase-shift keying - Differential Phase-shift Keying DPSK

Numerous versions have since emerged with different missiles, improved radars, better resistance to countermeasures, longer range and better capability against short-range ballistic missiles or targets flying at very low altitude. The closest western equivalent is the U.S. Patriot system. Compared to the Patriot the SA-10 is a much larger system with heavier, longer-ranged missiles. Both systems can engage multiple targets simultaneously, employ track-via-missile guidance, and rely on a single phased-array guidance radar to guide the ...

See also:

SA-10 Grumble, SA-10 Grumble - Variations, SA-10 Grumble - Guidance and warhead, SA-10 Grumble - History and upgrades, SA-10 Grumble - Radar, SA-10 Grumble - Users and other versions

Read more here: » SA-10 Grumble: Encyclopedia II - SA-10 Grumble - Variations

History of radar - Christian Huelsmeyer. In 1904 Christian Huelsmeyer gave public demonstrations in Germany and Netherlands of the use of radio echoes to detect ships so that collisions could be avoided. which consisted of a simple spark gap aimed using a multipole antenna. When a reflection was picked up by the two straight antennas attached to the separate receiver, a bell sounded. The system detected presence of ships up to 3 km, and he planned to extend its capability to 10km. It did not provide range informa ...

See also:

History of radar, History of radar - Before the twentieth century, History of radar - 1900s, History of radar - Christian Huelsmeyer, History of radar - Nikola Tesla, History of radar - Naval Research Laboratory, History of radar - Robert Watson-Watt, History of radar - Hans Hollmann, History of radar - World War II, History of radar - UK, History of radar - Germany, History of radar - US, History of radar - Cold War

Read more here: » History of radar: Encyclopedia II - History of radar - 1900s