Page 287 - Electrical Engineering Dictionary

where Y is a N-dimensional vector indexed fixed station (FS) that part of a radio com-
by a vector of parameters θ. See also munications system that is permanently lo-
Cramer-Rao bound. cated in a given geographical location. An-
other name for the base station in a cellular
fissile material an isotope which has a radio telephone network.
significant probability of undergoing nuclear
fission, e.g., U235, plutonium-239, thorium- fixed termination a broadband termina-
232, and enriched uranium. tion of a specific nominal impedance, usually
50 ohms, used to terminate the signal path of
fission the nuclear reaction in which a sin- a transmission line. Fixed terminations are
gle heavy nucleus is split into two or more used in the calibration of network analyzers
lighter nucleii called "daughter" products and and general microwave measurements.
emit highly energetic sub-atomic particles
plus energy in the process. fixed-gap head See disk head.

fixed channel assignment (FCA) a tech- fixed-head disk a disk in which one
nique of assigning radio channels in a com- read/write head unit is placed at every track
munications system in a fixed and prede- position. This eliminates the need for po-
termined way in accordance with predicted sitioning the head radially over the correct
rather than actual interference and propaga- track, thus eliminating the “seek” delay time.
tion conditions. Such assignments are not Rarely used today because modern disks con-
changed during radio transmission. sist of hundreds of tracks per disk surface,
making it economically infeasible to place a
fixed losses that component of the copper head unit at every track.
losses in DC shunt, short-shunt, and long-
shunt machines’ field circuit, that does not fixed-length instruction the machine lan-
vary with change in the load current. With guage instructions for a computer all have the
a fixed field power supply, it is an accepted same number of bits.
industry agreement to not consider the losses
in the field circuit rheostat in computing the fixed-point processor a processor capa-
efficiency and hence consider the field losses ble of operating on scaled integer and frac-
as fixed losses. tional data values.

fixed point See equilibrium point. fixed-point register a digital storage el-
ement used to manipulate data in a fixed-
fixed reference D/A converter the analog point representation system whereby each
output is proportional to a fixed (nonvarying) bit indicates an unscaled or unshifted binary
reference signal. value. Common encoding schemes utilized
in fixed-point registers include Unsigned Bi-
fixed resolution hierarchy an image pro- nary, Sign-Magnitude, and Binary Coded
cessing scheme in which the original and re- Decimal representations.
constructed image are of the same size. Pixel
values are refined as one moves from level fixed-point representation (1) a num-
to level. This is primarily used for progres- ber representation in which the radix point
sive transmission. Tree-structured VQ and is assumed to be located in a fixed posi-
transform-based hierarchical coding are two tion, yielding either an integer or a fraction
of the fixed resolution hierarchies. as the interpretation of the internal machine
representation. Contrast with floating-point
fixed shunt See shunt capacitor. representation.

c
2000 by CRC Press LLC