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Total internal reflection (TIR) is the optical phenomenon in which waves arriving at the interface (boundary) from one medium to another (e.g., from water to air) are not refracted into the second ("external") medium, but completely reflected back into the first ("internal") medium. It occurs when the second medium has a higher wave speed (lower refractive index) than the first, and the waves are incident at a sufficiently oblique angle on the interface. For example, the water-to-air surface in a typical fish tank, when viewed obliquely from below, reflects the underwater scene like a mirror with no loss of brightness (Fig. 1).

TIR occurs not only with electromagnetic waves such as light and microwaves, but also with other types of waves, including sound and water waves. If the waves are capable of forming a narrow beam (Fig. 2), the reflection tends to be described in terms of "rays" rather than waves; in a medium whose properties are independent of direction, such as air, water or glass, the "rays" are perpendicular to the associated wavefronts.

Refraction is generally accompanied by partial reflection. When waves are refracted from a medium of lower propagation speed (higher refractive index) to a medium of higher speed—e.g., from water to air—the angle of refraction (between the outgoing ray and the surface normal) is greater than the angle of incidence (between the incoming ray and the normal). As the angle of incidence approaches a certain threshold, called the critical angle, the angle of refraction approaches 90°, at which the refracted ray becomes parallel to the boundary surface. As the angle of incidence increases beyond the critical angle, the conditions of refraction can no longer be satisfied, so there is no refracted ray, and the partial reflection becomes total. For visible light, the critical angle is about 49° for incidence from water to air, and about 42° for incidence from common glass to air.

Details of the mechanism of TIR give rise to more subtle phenomena. While total reflection, by definition, involves no continuing flow of power across the interface between the two media, the external medium carries a so-called evanescent wave, which travels along the interface with an amplitude that falls off exponentially with distance from the interface. The "total" reflection is indeed total if the external medium is lossless (perfectly transparent), continuous, and of infinite extent, but can be conspicuously less than total if the evanescent wave is absorbed by a lossy external medium ("attenuated total reflectance"), or diverted by the outer boundary of the external medium or by objects embedded in that medium ("frustrated" TIR). Unlike partial reflection between transparent media, total internal reflection is accompanied by a non-trivial phase shift (not just zero or 180°) for each component of polarization (perpendicular or parallel to the plane of incidence), and the shifts vary with the angle of incidence. The explanation of this effect by Augustin-Jean Fresnel, in 1823, added to the evidence in favor of the wave theory of light.

The phase shifts are utilized by Fresnel's invention, the Fresnel rhomb, to modify polarization. The efficiency of the total internal reflection is exploited by optical fibers (used in telecommunications cables and in image-forming fiberscopes), and by reflective prisms, such as image-erecting Porro/roof prisms for monoculars and binoculars.

INFO: Full form for TIR is Total Indicated Run in Electronics category
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INFO: Full form for PBL is Poly-buffered Locos in Electronics category
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INFO: Full form for PDR is Polarization Differential Reflectance in Electronics category
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INFO: Full form for FOP is Forced Output Power in Electronics category
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INFO: Full form for FDE is Frequency Domain Experiment in Electronics category
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INFO: Full form for SSV is Steady-state Value in Electronics category
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INFO: Full form for TDK is Tokyo Denki Kagaku in Electronics category
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INFO: Full form for MLF is Micro-lead Frame in Electronics category
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INFO: Full form for MLJ is Multi-layer Junction in Electronics category
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INFO: Full form for PBA is Printed Board Assembly in Electronics category
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Amplitude-shift keying (ASK) is a form of amplitude modulation that represents digital data as variations in the amplitude of a carrier wave.In an ASK system, a symbol, representing one or more bits, is sent by transmitting a fixed-amplitude carrier wave at a fixed frequency for a specific time duration. For example, if each symbol represents a single bit, then the carrier signal will be transmitted when the input value is 1, but will not be transmitted when the input value is 0.

Any digital modulation scheme uses a finite number of distinct signals to represent digital data. ASK uses a finite number of amplitudes, each assigned a unique pattern of binary digits. Usually, each amplitude encodes an equal number of bits. Each pattern of bits forms the symbol that is represented by the particular amplitude. The demodulator, which is designed specifically for the symbol-set used by the modulator, determines the amplitude of the received signal and maps it back to the symbol it represents, thus recovering the original data. Frequency and phase of the carrier are kept constant.

Like AM, an ASK is also linear and sensitive to atmospheric noise, distortions, propagation conditions on different routes in PSTN, etc. Both ASK modulation and demodulation processes are relatively inexpensive. The ASK technique is also commonly used to transmit digital data over optical fiber. For LED transmitters, binary 1 is represented by a short pulse of light and binary 0 by the absence of light. Laser transmitters normally have a fixed "bias" current that causes the device to emit a low light level. This low level represents binary 0, while a higher-amplitude lightwave represents binary 1.

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 (OOK), 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; an eight-level scheme can represent three bits; and so on. These forms of amplitude-shift keying require a high signal-to-noise ratio for their recovery, as by their nature much of the signal is transmitted at reduced power.

ASK system can be divided into three blocks. The first one represents the transmitter, the second one is a linear model of the effects of the channel, the third one shows the structure of the receiver. The following notation is used:

Different symbols are represented with different voltages. If the maximum allowed value for the voltage is A, then all the possible values are in the range [−A, A] and they are given by:

the difference between one voltage and the other is:

INFO: Full form for OVD is Outside Vapor Deposition in Electronics category
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Teledyne Technologies Incorporated is an American industrial conglomerate. It was founded in 1960, as Teledyne, Inc., by Henry Singleton and George Kozmetsky.

From August 1996 to November 1999, Teledyne existed as part of the conglomerate Allegheny Teledyne Incorporated – a combination of the former Teledyne, Inc., and the former Allegheny Ludlum Corporation. On November 29, 1999, three separate entities, Teledyne Technologies, Allegheny Technologies, and Water Pik Technologies, were spun off as free-standing public companies. Allegheny Technologies retained several companies of the former Teledyne, Inc. that fit with Allegheny's core business of steel and exotic metals production.

At various times, Teledyne, Inc., had more than 150 companies with interests as varied as insurance, dental appliances, specialty metals, and aerospace electronics, but many of these had been divested prior to the merger with Allegheny. The new Teledyne Technologies was initially composed of 19 companies that were earlier in Teledyne, Inc. By 2011, Teledyne Technologies had grown to include nearly 100 companies.

INFO: Full form for SVI is Smart Virtual Instrument in Electronics category
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INFO: Full form for SVI is Speaker Verification and Identification in Electronics category
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INFO: Full form for APW is Augmented Plane Wave in Electronics category
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INFO: Full form for OTL is Output Transformer Loss in Electronics category
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INFO: Full form for OPW is Orthogonalized Plane Wave in Electronics category
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INFO: Full form for SVS is Synthetyc Vision System in Electronics category
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INFO: Full form for OPL is Optically Pumped Laser in Electronics category
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INFO: Full form for OLB is Outer Lead Bond in Electronics category
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INFO: Full form for SPP is Single-phase Printing in Electronics category
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INFO: Full form for AET is Aircraft Electronics Technician in Electronics category
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INFO: Full form for MEV is Mega-electronvolt in Electronics category
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INFO: Full form for MFU is Machinenf in Electronics category
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