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netic radiation from that object. 2. The eclipsing
of one object by another.
occupied band A frequency band used by at least
one transmitting station regularly.
occupied bandwidth For a given emission, the
continuous band of frequencies (f 2 f 1 ) for which
the mean (average) radiated power above f 2 and
below f 1 is 0.5 percent of the total mean radiated
power.
occupied orbit In an atom, an orbit in which an
electron is present.
Ocean Phonetic alphabet code word for the letter O.
OCR Abbreviation of OPTICAL CHARACTER REC-
OGNITION.
oct Abbreviation of OCTAL.
octal Abbreviation, oct. Based on the number eight.
See, for example, OCTAL NUMBER SYSTEM.
octal digit One of the figures in the group 0
through 7 used in the OCTAL NUMBER SYSTEM.
octal notation See OCTAL NUMBER SYSTEM.
octal number system The base-eight system of
number notation. It uses digits 0 through 7.
Compare BINARY NUMBER SYSTEM and DECI-
MAL NUMBER SYSTEM. The octal system is often
used as shorthand for otherwise-cumbersome binary
numbers. The binary number is separated
into groups of three digits from right to left; each
such group is then converted into its decimal
equivalent, with the result being the octal form of
the binary number [e.g., binary 111 001 011 = octal
713 (111 = decimal 7; 001 = decimal 1; and
011 = decimal 3)].
Decimal Octal
0 0
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 10
9 11
10 12
11 13
12 14
13 15
14 16
15 17
16 20
octal number system
octal-to-decimal conversion Conversion of numbers
in the octal number system to numbers in
the more-familiar decimal number system.
This is done by expressing the octal number serially
in powers of eight. Thus, octal 12 = (1 × 8 1 ) +
(2 × 8 0 ) = 8 + 2 = decimal 10.
octant One-eighth of a circle; therefore, 45 degrees,
or 0.5 quadrant.
octave 1. The range of frequencies between a given
frequency ( f ) and twice that frequency (2f ).
2. The range of frequencies between a given frequency
( f ) and half that frequency ( f/2).
octave band A band of frequencies one octave wide
(see OCTAVE).
octave-band noise analyzer A noise analyzer having
bandpass-filter channels whose center frequencies
are one octave apart.
octave-band pressure level Sound pressure level
within an OCTAVE BAND.
octave pressure level See OCTAVE-BAND PRES-
SURE LEVEL.
OCTL Abbreviation of OPEN-CIRCUITED TRANS-
MISSION LINE.
octonary signal An eight-level signaling code.
octonary system See OCTAL NUMBER SYSTEM.
OD Abbreviation of OUTSIDE DIAMETER.
odd-even check A method of checking the integrity
of data transferred in a computer system, in which
each word carries an extra digit to show whether
the sum of ones in the word is odd or even.
odd harmonic In a complex waveform, a harmonic
that is an odd-numbered multiple of the fundamental
frequency (e.g., third harmonic, fifth harmonic,
etc.). Compare EVEN HARMONIC.
odd-harmonic intensification In a complex waveform,
emphasis of the amplitude of odd harmonics,
with respect to that of even harmonics, a
property of some multivibrators and nonsinusoidal
waves.
odd line In a conventional television picture, one
of the 262.5 odd-numbered horizontal lines
scanned by the electron beam in developing the
odd-line field. Compare EVEN LINE.
odd-line field On a conventional television screen,
the complete field obtained when the electron
beam has traced all the odd-numbered lines.
Compare EVEN-LINE FIELD.
odd-line interlace See ODD-LINE FIELD.
odd parity check A computer check for an odd
number of ones or zeros in digital data.
Odex Trade name for a series of autonomous
robots developed by Odetics, Inc. They use legs
for locomotion. Noted for their ability to maneuver
in places that most robots cannot reach.
odograph An electromechanical or electronic plotter
that traces the path of a vehicle on a map, or
on the image of a map as portrayed on a display
screen.
odometer An electromechanical device that indicates
the speed of, and distance covered by, a
moving vehicle or robot. Some such devices give a
constant position indication, via mathematical
integration of the measured velocity (speed and
direction), relative to time. It can function in one,
two, or three dimensions.
odometry A method of speed, velocity, and/or position
sensing. It is commonly used in mobile