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Words begining with "B"
Band
- In radio, a continuous sequence of broadcastinq frequencies
within given limits.
- 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.
- 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
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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