Pair gain

In telephony, pair gain is a method of transmitting multiple POTS signals over the twisted pairs traditionally used for a single traditional subscriber line in telephone systems. Pair gain has the effect of creating additional subscriber lines. This is typically used as an expedient way to solve subscriber line shortage problems by using existing wiring, instead of installing new wires from the central office to the customer premises. The term was invented in the middle 20th century by analogy with earlier use of gain to extend telephone local loops far from the telephone exchange.

A pair gain system consists of concentrators or multiplexers which combine the separate signals into a single signal which is transmitted through the existing copper cable pair. The signals are then separated into individual subscriber lines at the customer premises. The pair gain unit which performs the multiplexing can simply provide a second telephone connection over a single subscriber line (called an Analog Multi-Line Carrier or AML) in circumstances where a customer wants to add a new phone line for a fax machine or dial-up internet connection. A larger analog pair gain system made by Anaconda in the 1960s provided seven lines. Some pair gain units can expand the number of subscriber lines available over a single copper pair to as many as sixty. Large pair gain units are stored in serving area interfaces or metal cabinets typically resembling small apartment-sized refrigerators alongside or near roadways that overlie communications rights-of-way.

Pair

Pair may refer to:

Medicine

Pair (parliamentary convention)

In parliamentary practice, pairing is an informal arrangement between the government and opposition parties whereby a member of a House of Parliament agrees or is designated by the party whip to abstain from voting while a member of the other party needs to be absent from the House due to other commitments, illness, travel problems, etc. A pairing would usually be arranged or approved by the party whips and will usually not apply for critical votes, such as no-confidence votes.

The member abstaining from voting is referred to as a pair. In the United States, pairing is an informal arrangement between members and the pairs are called live pairs.

An alternative method of maintaining the relative voting positions of parties in a legislative body is proxy voting, which is used, for example, in New Zealand.

Examples

Australia

In Australia, following the 2010 federal election, the Gillard Government formed a minority government with the support of a number of votes from minor parties and independents, and the Opposition refused to grant automatic pairing, leading to some embarrassment and reversals for the opposition when, for example, a pair was initially not given for a member to care for her sick baby or to attend at the birth of his baby.

Ordered pair

In mathematics, an ordered pair (a, b) is a pair of mathematical objects. The order in which the objects appear in the pair is significant: the ordered pair (a, b) is different from the ordered pair (b, a) unless a = b. (In contrast, the unordered pair {a, b} equals the unordered pair {b, a}.)

Ordered pairs are also called 2-tuples, or sequences of length 2; ordered pairs of scalars are also called 2-dimensional vectors. The entries of an ordered pair can be other ordered pairs, enabling the recursive definition of ordered n-tuples (ordered lists of n objects). For example, the ordered triple (a,b,c) can be defined as (a, (b,c)), i.e., as one pair nested in another.

In the ordered pair (a, b), the object a is called the first entry, and the object b the second entry of the pair. Alternatively, the objects are called the first and second coordinates, or the left and right projections of the ordered pair.

Cartesian products and binary relations (and hence functions) are defined in terms of ordered pairs.

Gain

Gain may refer to:

Increase of quantity

People

Products

Music

Acronyms

Other uses

Gain (projection screens)

Gain is a property of a projection screen, and is one of the specifications quoted by projection screen manufacturers.

Interpretation

The number that is typically measured is called the peak gain at zero degrees viewing axis, and represents the gain value for a viewer seated along a line perpendicular to the screen's viewing surface. The gain value represent the ratio of brightness of the screen relative to a set standard (in this case, a sheet of magnesium carbonate). Screens with a higher brightness than this standard are rated with a gain higher than 1.0, while screens with lower brightness are rated from 0.0 to 1.0. Since a projection screen is designed to scatter the impinging light back to the viewers, the scattering can either be highly diffuse or highly concentrated. Highly concentrated scatter results in a higher screen gain (a brighter image) at the cost of a more limited viewing angle (as measured by the half-gain viewing angle), whereas highly diffuse scattering results in lower screen gain (a dimmer image) with the benefit of a wider viewing angle.

Gain (electronics)

In electronics, gain is a measure of the ability of a two port circuit (often an amplifier) to increase the power or amplitude of a signal from the input to the output port by adding energy converted from some power supply to the signal. It is usually defined as the mean ratio of the signal amplitude or power at the output port to the amplitude or power at the input port. It is often expressed using the logarithmic decibel (dB) units ("dB gain"). A gain greater than one (zero dB), that is amplification, is the defining property of an active component or circuit, while a passive circuit will have a gain of less than one.

The term gain alone is ambiguous, and can refer to the ratio of output to input voltage (voltage gain), current (current gain) or electric power (power gain). In the field of audio and general purpose amplifiers, especially operational amplifiers, the term usually refers to voltage gain, but in radio frequency amplifiers it usually refers to power gain. Furthermore, the term gain is also applied in systems such as sensors where the input and output have different units; in such cases the gain units must be specified, as in "5 microvolts per photon" for the responsivity of a photosensor. The "gain" of a bipolar transistor normally refers to forward current transfer ratio, either h_FE ("Beta", the static ratio of I_c divided by I_b at some operating point), or sometimes h_fe (the small-signal current gain, the slope of the graph of I_c against I_b at a point).