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A B C D E F G H I J K L M N O P R S T U V W Y Z


Words begining with "B"

Band

  1. In radio, a continuous sequence of broadcastinq frequencies within given limits.

     

  2. In radiometry, a relatively narrow region of the electromagnetic spectrum to which a remote sensor responds; a multispectral sensor makes measurements in a number of spectral bands.

     

  3. In spectroscopy, spectral regions where atmospheric gases absorb (and emit) radiation, e.g., the 15 um carbon dioxide absorption band, the 6.3 um water vapor absorption band, and the 9.6 um ozone absorption band.

Bandwidth

The total range of frequency required to pass a specific modulated signal without distortion or loss of data. The ideal bandwidth allows the signal to pass under conditions of maximum AM or FM adjustment. (Too narrow a bandwidth will result in loss of data during modulation peaks. Too wide a bandwidth will pass excessive noise along with the signal.) In FM, radio frequency signal bandwidth is determined by the frequency deviation of the signal.

Barometer

An instrument used to measure atmospheric pressure. A standard mercury barometer has a glass column about 30 inches long, closed at one end, with a mercury-filled reservoir. Mercury in the tube adjusts until the weight of the mercury column balances the atmospheric force exerted on the reservoir High atmospheric pressure forces the mercury higher in the column. Low pressure allows the mercury to drop to a lower level in the column. An aneroid barometer uses a small. flexible metal box called an aneroid cell. The box is tightly sealed after some of the air is removed, so that small changes in external air pressure cause the cell to expand or contract.

Base

A substance that forms a salt when it reacts with acid. A base is a substance that removes hydrogen ions (protons) from an acid and combines with them in a chemical reaction

Baud

Unit of signaling speed. The speed in bauds is the number of discrete conditions or signal events per second. If each signal event represents only one bit condition, baud is the same as bits per second.

Bay

A wide area of water extending into land from a sea or lake.

Beamwidth

The measure of the "width" of an antenna pattern, measured in degrees of arc. Generally an antenna with low gain has a wide pattern, receiving signals well from a number of different directions. See antenna.

Bearing

The combination of antenna azimuth and elevation required to point (aim) an antenna at a spacecraft. The bearing for geostationary (i.e., GOES) satellites is constant. The bearing for polar-orbiting satellites varies continuously.

Beginners All-purpose Symbolic Instruction Code (BASIC)

A most popular and widespread "high level" language for microcomputers. BASIC uses a sequence of English-like commands and statements.

Binary

A numbering system that uses only 1 and 0 (e.g., 1 is one, 10 is two, 11 is three). In digital integrated circuits, a 0 is indicated by a logic low and a 1 by a logic high.

Bioassay

A measurement of the effects of a substance on living organisms.

Biodegradation

Decomposition of material by microorganisms.

Biogeochemical Cycles

Movements through the Earth system of key chemical constituents essential to life, such as carbon, nitrogen, oxygen, and phosphorus.

Biomass

The amount of living material in unit area or volume, usually expressed as mass or weight.

Biome

Well-defined terrestrial environment (e.g., desert, tundra, or tropical forest). The complex of living organisms found in an ecological region.

Biosphere

Part of the Earth system in which life can exist, between the outer portion of the geosphere and the inner portion of the atmosphere.

Biota

The plant and animal life of a region or area.

Bit

A contraction of "binary digit." The basic element of a two-element (binary) computer language.

Bit Rate

The speed at which bits are transmitted, usually expressed in bits per second. See baud.

Blizzard

A severe weather condition characterized by low temperatures and strong winds (greater than 35 mph) bearing a great amount of snow, either falling or blowing. When these conditions persist after snow has stopped falling, it is called a qround blizzard.

Boundaries

Lines indicating the limits of countries, states, or other political jurisdictions, or different air mssses

British Thermal Unit (BTU)

The amount of heat needed to raise the temperature of one pound of water by one degree Fahrenheit. Compare with

Bus

The basic frame of a satellite system that includes the propulsion and stabilization systems, but not the instruments or data systems.

Byte

A unit of eight bits of data or memory in microcomputer systems.


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Editor: Tom Benson
NASA Official: Tom Benson
Last Updated: Jun 12 2014

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