Multi-band device

In telecommunications, a multi-band device (including dual-band, tri-band, quad-band and penta-band devices) is a communication device (especially a mobile phone) that supports multiple radio frequency bands. All devices which have more than one channel use multiple frequencies; a band however is a group of frequencies containing many channels. Multiple bands in mobile devices support roaming between different regions where different standards are used for mobile telephone services. Where the bands are widely separated in frequency, parallel transmit and receive signal path circuits must be provided, which increases the cost, complexity and power demand of multi-band devices.

The term quad-band describes a device that supports four frequency bands: 850 and 1900 MHz, mostly used in the Americas (ITU region 2), and the 900 and 1800 MHz bands used elsewhere. Most GSM/UMTS phones support all four bands, while most CDMA/1xRTT phones do not, and so are considered only dual-band devices. A few phones support both of the domestic frequencies but only one foreign one for limited roaming, making them tri-band phones.

Quad (play)

Quad is a television play by Samuel Beckett, written and first produced and broadcast in 1981. It first appeared in print in 1984 (Faber and Faber) where the work is described as "[a] piece for four players, light and percussion" and has also been called a "ballet for four people."

It consists of four actors dressed in robes, hunched and silently walking around and diagonally across a square stage in fixed patterns, alternately entering and exiting. Each actor wears a distinct colored robe (white, red, blue, yellow), and is accompanied by a distinct percussion instrument (leitmotif). The actors walk in sync (except when entering or exiting), always on one of four rotationally symmetric paths (e.g., when one actor is at a corner, so are all others; when one actor crosses the stage, all do so together, etc.), and never touch – when walking around the stage, they move in the same direction, while when crossing the stage diagonally, where they would touch in the middle, they avoid the center area (walking around it, always clockwise or always anti-clockwise, depending on the production). In the original production, the play was first performed once, and then, after a pause, an abbreviated version is performed a second time, this time in black and white and without musical accompaniment. These are distinguished as Quad I and Quad II, though Quad II does not appear in print.

Quad (music)

Quad or QUAD was the name of a solo music project by Gary Ramon.

During his six-year hiatus from Sun Dial, Ramon embarked on an ambitious solo project, Quad, which combined ambient electronica with kraut rock. The result was a pair of self-titled albums. The first of these was released on Ramon's own Acme Records in 1997 as a 1000-copy limited edition on 12" clear vinyl with a transparent sleeve. The second Quad album was released in 1998 on the Prescription label as a 99-copy limited edition LP.

A 1999 American re-release of the first album on CD and 10" LP on the Man's Ruin label was scheduled, but eventually cancelled.

Both albums are now highly sought-after collectors' items.

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Quad (rocket)

In rocketry, the Armadillo Aerospace Quad vehicle called Pixel is a computer controlled VTVL rocket that was used in 2006 to compete in the Lunar Lander Challenge.

General description

The quad vehicle design is a pressure fed in blow-down mode from an initial pressure of 320 psi for level 1 (400 psi level 2). The cold gas vernier engines are cross-fed by gas drawn from ullage space of the opposite tank. The vehicle was able to transfer propellant through connecting pipes between opposite tanks by controlling ullage pressures with the thrusters; this helps it balance, minimizing gas use. The main engine had two-axis thrust vectoring. The vehicle was fully computer controlled; with guidance from GPS and fiber optic gyros.

Specification

The specification for Pixel/Texel for level 1: