Binary phase

In materials chemistry, a binary phase is a chemical compound containing two different elements. Some binary phases compounds are molecular, e.g. carbon tetrachloride (CCl4). More typically binary phase refers to extended solids. Famous examples are the two polymorphs of zinc sulfide.[1]

Phases with higher degrees of complexity feature more elements, e.g. three elements in ternary phases, four elements in quaternary phases,

NaCl polyhedra
Sodium chloride is a famous binary phase. It features two elements: Na and Cl.

References

  1. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9.
Barker code

A Barker code or Barker sequence is a finite sequence of N values of +1 and −1,

with the ideal autocorrelation property, such that the off-peak (non-cyclic) autocorrelation coefficients

are as small as possible:

for all .

Only nine Barker sequences are known, all of length N at most 13. Barker's 1953 paper asked for sequences with the stronger condition

Only four such sequences are known, shown in bold in the table below. http://paper.uscip.us/jaece/JAECE.2014.1003.pdf

Carrier interferometry

Carrier Interferometry (CI) is a spread spectrum scheme designed to be used in an Orthogonal Frequency-Division Multiplexing (OFDM) communication system for multiplexing and multiple access, enabling the system to support multiple users at the same time over the same frequency band.

Like MC-CDMA, CI-OFDM spreads each data symbol in the frequency domain. That is, each data symbol is carried over multiple OFDM subcarriers. But unlike MC-CDMA, which uses binary-phase Hadamard codes (code values of 0 or 180 degrees) or binary pseudonoise, CI codes are complex-valued orthogonal codes. In the simplest case, CI code values are coefficients of a discrete Fourier transform (DFT) matrix. Each row or column of the DFT matrix provides an orthogonal CI spreading code which spreads a data symbol. Spreading is achieved by multiplying a vector of data symbols by the DFT matrix to produce a vector of coded data symbols, then each coded data symbol is mapped to an OFDM subcarrier via an input bin of an inverse fast Fourier transform (IFFT). A block of contiguous subcarriers may be selected, or to achieve better frequency diversity, non-contiguous subcarriers distributed over a wide frequency band can be used. A guard interval, such as a cyclic prefix (CP), is added to the baseband CI-OFDM signal before the signal is processed by a radio front-end to convert it to an RF signal, which is then transmitted by an antenna.

A significant advantage of CI-OFDM over other OFDM techniques is that CI spreading shapes the time-domain characteristics of the transmitted waveform. Thus, CI-OFDM signals have a much lower peak-to-average-power ratio (PAPR), or crest factor, compared to other types of OFDM. This greatly improves power efficiency and reduces the cost of power amplifiers used in the radio transmitter.

A CI-OFDM receiver removes the cyclic prefix from a received CI-OFDM transmission and performs OFDM demodulation with a DFT (e.g., an FFT) typically used in OFDM receivers. The CI-spread symbol values are collected from their respective subcarriers in an inverse-mapping process and may be equalized to compensate for multipath fading or processed for spatial demultiplexing. The CI de-spreader performs an inverse-DFT on the spread symbols to recover the original data symbols.

Since CI coding can shape the time-domain characteristics of the transmitted waveform, it can be used to synthesize various waveforms, such as direct-sequence spread spectrum and frequency shift key [4] signals. The advantage is that the receiver can select time-domain or frequency-domain equalization based on how much scattering occurs in the transmission channel. For rich scattering environments, frequency-domain equalization using FFTs requires less computation than conventional time-domain equalization and performs substantially better.

Cr23C6 crystal structure

Cr23C6 is the prototypical compound of a common crystal structure, discovered in 1933 as part of the chromium-carbon binary phase diagram. Over 85 known compounds adopt this structure type, which can be described as a NaCl-like packing of chromium cubes and cuboctahedra.

DVB-S

Digital Video Broadcasting – Satellite (DVB-S) is the original DVB standard for Satellite Television and dates from 1995, in its first release, while development lasted from 1993 to 1997. The first commercial application was by Galaxy in Australia, enabling digitally broadcast, satellite-delivered Television to the public.

It is used via satellites serving every continent of the world. DVB-S is used in both Multiple Channel Per Carrier (MCPC) and Single channel per carrier modes for Broadcast Network feeds as well as for direct-broadcast satellite services like Sky (UK & Ireland) via Astra in Europe, Dish Network and Globecast in the U.S. and Bell TV in Canada.

While the actual DVB-S standard only specifies physical link characteristics and framing, the overlaid transport stream delivered by DVB-S is mandated as MPEG-2, known as MPEG transport stream (MPEG-TS).

Some amateur television repeaters also use this mode in the 1.2 GHz amateur band.

Halide

A halide is a binary phase, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a fluoride, chloride, bromide, iodide, astatide, or theoretically tennesside compound. The alkali metals combine directly with halogens under appropriate conditions forming halides of the general formula, MX (X = F, Cl, Br or I). Many salts are halides; the hal- syllable in halide and halite reflects this correlation. All Group 1 metals form halides that are white solids at room temperature.

A halide ion is a halogen atom bearing a negative charge. The halide anions are fluoride (F−), chloride (Cl−), bromide (Br−), iodide (I−) and astatide (At−). Such ions are present in all ionic halide salts. Halide minerals contain halides.

All these halides are colourless, high melting crystalline solids having high negative enthalpies of formation.

ICube-1

iCube-1 is a miniaturised satellite built by the Institute of Space Technology in Pakistan, with an objective to provide a wide range of future experiments in the domain of imaging, microgravity, biology, nanotechnology, space dynamics, chemistry, space physics and various other fields. It can also provide a testbed for developing satellite constellations for specific applications.

Launched in Low Earth Orbit, onboard Dnepr launch vehicle from Dombarovsky, Russia. It houses several sensors to collect data for scientific purposes. iCUBE-1 is a fully autonomous satellite and is capable of maintaining its health via its on-board computer. It is a single-unit CubeSat, cubic in shape with sides of 10 centimetres (3.9 in). Five sides of the satellites carry two triple-junction (ATJ) solar cells, providing the spacecraft with 2 watts of power. Each cell has dimensions of 40 by 80 millimetres (1.6 in × 3.1 in), and at the beginning of operations has an efficiency of at least 27.5% at 25°C.

iCube-1 carries a camera with a resolution of 640 by 480 pixels. Communications with the ground are achieved through a 435.060 MHz uplink audio frequency-shift keying to provide a datarate of 1,200 bits per second. The 145.947 MHz downlink, which uses binary phase-shift keying, also provides a datarate of 1,200 bits per second. The satellite also carries CW and AX25 beacons. The programme cost around 3-3.5 million rupees.

Spokesperson IST Raza Butt said that it’s a positive move for technology in Pakistan.

“The world is moving towards miniaturization. The launch cost is significantly low for CubeSats as compared to the bigger satellites. The low cost factor is very attractive for researchers who can test their payloads using these cubesats and then incorporate this technology in their bigger satellites,” he commented.

Initially, iCUBE-1 will transmit a Continuous Wave Morse coded beacon with message “iCUBE-1 First CubeSat of Pakistan”. Amateur radio operators have a great opportunity to hear those signals on the VHF band. The satellite will send its health data to ground stations and can also be commanded from Satellite tracking and Control Station at IST.

Indium halides

There are three sets of indium halides, the trihalides, the monohalides, and several intermediate halides.

In the monohalides the oxidation state of indium is +1 and their proper names are indium(I) fluoride, indium(I) chloride, indium(I) bromide and indium(I) iodide.

The intermediate halides contain indium with oxidation states, +1, +2 and +3.

Lever rule

The lever rule is a tool used to determine the mole fraction (xi) or the mass fraction (wi) of each phase of a binary equilibrium phase diagram. It can be used to determine the fraction of liquid and solid phases for a given binary composition and temperature that is between the liquidus and solidus line.

In an alloy or a mixture with two phases, α and β, which themselves contain two elements, A and B, the lever rule states that the mass fraction of the α phase is

where

all at some fixed temperature or pressure.

List of amateur radio modes

The following is a list of the modes of radio communication used in the amateur radio hobby.

List of materials properties

A material's property (or material property) is an intensive property of some material, i.e. a physical property that does not depend on the amount of the material. These quantitative properties may be used as a metric by which the benefits of one material versus another can be compared, thereby aiding in materials selection.

A property may be a constant or may be a function of one or more independent variables, such as temperature. Materials properties often vary to some degree according to the direction in the material in which they are measured, a condition referred to as anisotropy. Materials properties that relate to different physical phenomena often behave linearly (or approximately so) in a given operating range. Modeling them as linear can significantly simplify the differential constitutive equations that the property describes.

Some materials are used in relevant equations to predict the attributes of a system a priori.

The properties are measured by standardized test methods. Many such methods have been documented by their respective user communities and published through the Internet; see ASTM International.

On-off keying

On-off keying (OOK) denotes the simplest form of amplitude-shift keying (ASK) modulation that represents digital data at the presence or absence of a carrier wave. In its simplest form, the presence of a carrier for a specific duration represents a binary one, while its absence for the same duration represents a binary zero. Some more sophisticated schemes vary these durations to convey additional information. It is analogous to unipolar encoding line code.

On-off keying is most commonly used to transmit Morse code over radio frequencies (referred to as CW (continuous wave) operation), although in principle any digital encoding scheme may be used. OOK has been used in the ISM bands to transfer data between computers, for example.

OOK is more spectrally efficient than frequency-shift keying, but more sensitive to noise when using a regenerative receiver or a poorly implemented superheterodyne receiver.

For a given data rate, the bandwidth of a BPSK (Binary Phase Shift keying) signal and the bandwidth of OOK signal are equal.

In addition to RF carrier waves, OOK is also used in optical communication systems (e.g. IrDA).

In aviation, some possibly unmanned airports have equipment that let pilots key their VHF radio a number of times in order to request an Automatic Terminal Information Service broadcast, or turn on runway lights.

Phase-shift keying

Phase-shift keying (PSK) is a digital modulation process which conveys data by changing (modulating) the phase of a constant frequency reference signal (the carrier wave). The modulation is accomplished by varying the sine and cosine inputs at a precise time. It is widely used for wireless LANs, RFID and Bluetooth communication.

Any digital modulation scheme uses a finite number of distinct signals to represent digital data. PSK uses a finite number of phases, each assigned a unique pattern of binary digits. Usually, each phase encodes an equal number of bits. Each pattern of bits forms the symbol that is represented by the particular phase. The demodulator, which is designed specifically for the symbol-set used by the modulator, determines the phase of the received signal and maps it back to the symbol it represents, thus recovering the original data. This requires the receiver to be able to compare the phase of the received signal to a reference signal – such a system is termed coherent (and referred to as CPSK).

CPSK requires a complicated demodulator, because it must extract the reference wave from the received signal and keep track of it, to compare each sample to. Alternatively, the phase shift of each symbol sent can be measured with respect to the phase of the previous symbol sent. Because the symbols are encoded in the difference in phase between successive samples, this is called differential phase-shift keying (DPSK). DPSK can be significantly simpler to implement than ordinary PSK, as it is a 'non-coherent' scheme, i.e. there is no need for the demodulator to keep track of a reference wave. A trade-off is that it has more demodulation errors.

Phase diagram

For the use of this term in mathematics and physics, see phase space.A phase diagram in physical chemistry, engineering, mineralogy, and materials science is a type of chart used to show conditions (pressure, temperature, volume, etc.) at which thermodynamically distinct phases (such as solid, liquid or gaseous states) occur and coexist at equilibrium.

Rhenium(IV) chloride

Rhenium(IV) chloride is the inorganic compound with the formula ReCl4. This black solid is of interest as a binary phase but otherwise is of little practical value. A second polymorph of ReCl4 is also known.

Sigfox

Sigfox is a French global network operator founded in 2009 that builds wireless networks to connect low-power objects such as electricity meters and smartwatches, which need to be continuously on and emitting small amounts of data.

Sigfox is based in Labège near Toulouse, France, and has over 375 employees. The firm also has offices in Madrid, San Francisco, Sydney and Paris.

Solid solution

A solid solution is a solid-state solution of one or more solutes in a solvent. Such a multi-component system is considered a solution rather than a compound when the crystal structure of the solvent remains unchanged by addition of the solutes, and when the chemical components remain in a single homogeneous phase. This often happens when the two elements (generally metals) involved are close together on the periodic table; conversely, a chemical compound generally results when two metals involved are not near each other on the periodic table.The solid solution needs to be distinguished from mechanical mixtures of powdered solids like two salts, sugar and salt, etc. The mechanical mixtures have total or partial miscibility gap in solid state.

Examples of solid solutions include crystallized salts from their liquid mixture, metal alloys, moist solids. In the case of metal alloys intermetallic compounds occur frequently.

Ted Paige

Professor Edward George Sydney Paige FRS (18 July 1930 – 20 February 2004), known as Ted Paige, was a British physicist and engineer. His main areas of research were semiconductor devices to improve radar, including work on surface acoustic waves, and optical techniques using programmable phase plates.

Ternary signal

In telecommunication, a ternary signal is a signal that can assume, at any given instant, one of three states or significant conditions, such as power level, phase position, pulse duration, or frequency.

Examples of ternary signals are (a) a pulse that can have a positive, zero, or negative voltage value at any given instant (PAM-3), (b) a sine wave that can assume phases of 0°, 120°, or 240° relative to a clock pulse (3-PSK), and (c) a carrier signal that can assume any one of three different frequencies depending on three different modulation signal significant conditions (3-FM).

Some examples of PAM-3 line codes that use ternary signals are:

hybrid ternary code

bipolar encoding

MLT-3 encoding used in 100BASE-TX Ethernet

B3ZS

4B3T used in some ISDN basic rate interface

8B6T used in 100BASE-T4 Ethernet

return-to-zero

SOQPSK-TG uses ternary continuous phase modulation3-PSK can be seen as falling between "binary phase-shift keying" (BPSK), which uses two phases, and "quadrature phase-shift keying" (QPSK), which uses four phases.

Two-phase

Two-phase may refer to:

Two-phase electric power

Two-phase commit protocol

Two-phase flow

Two-phase locking

Binary phase, chemical compounds composed of two elements

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