Page 304 - Electrical Engineering Dictionary

fresh fuel nuclear fuel which has never a radio communication link given the amount
participated in a nuclear reaction and is thus of power transmitted, the effective apertures
only slightly radioactive. or gains of the transmit and receive antennas,
the distance between the antennas, and the
Fresnel region the region in space around wavelength.
anantennaatwhichthefieldshavebothtrans-
verse and radial components and the antenna fringing the portion of the flux at the air
pattern is dependent on the distance from the gap in a magnetic circuit that does not follow
antenna. The Fresnel, or near-field, region the shortest path between the poles.
2
is typically taken to be r< 2D /λ, where
r is the distance from the antenna, D is the
frit a relatively low softening point mate-
maximum dimension of the antenna, and λ is
rial of glass composition.
the wavelength.
Fresnel zone an indicator of the signif- Fritchmanmodel N-stateMarkoffmodel
icant volume of space occupied by a radio describing N error states of a channel.
wave propagating along a line-of-sight path
between the transmitter and receiver. At an frog the top of a tower.
arbitrary point which is at distance d 1 from
the transmitter and at distance d 2 from the front end (1) an initial processing unit that
receiver, along the axis joining the trans- provides a user interface and/or reformats
mitter and the receiver, a radio wave with input data for subsequent computations on
wavelength λ occupies a volume, which at a special-purpose or high-performance back
that point between the transmitter and the re- end processor.
ceiver, has a radius which is given by the ra- (2) the portion of the compiler that does
dius of the first Fresnel zone. The radius of machine-independent analysis.
the first Fresnel zone is given by
s
front of a motor the end of a motor that
λd 1 d 2
R = is opposite to the major coupling or driving
d 1 + d 2
pulley.
From this equation one can see that the sig-
nificant volume occupied by a radio wave is
front porch video blanking level duration
essentially ellipsoidal. In order for a trans-
of approximately 1.27 microseconds con-
mitter and receiver to communicate success-
tained within the horizontal blanking inter-
fully, it is important for this volume to be
val of the composite NTSC signal. The front
kept free from any obstruction, especially at
porch duration is 2% of the total horizontal
microwave frequencies.
line time, starting at the end of a horizontal
line of video signals and ending at the begin-
fricative a phoneme pronounced when
ning of the horizontal line sync signal.
constricting the vocal tract so as the air
flow becomes turbulent and the correspond-
frontside bus the term used to describe
ing frequency spectrum looks like a broad-
the main bus connecting the processor to the
band noise. The utterances with frication
main memory (cf. backside bus).
can occur with or without phonation. When
phonation also occurs, the presence of for-
mants can be detected in the spectrum. frustrated total reflection See attenuated
total reflection.
Friis transmission formula a formula
used to compute the received signal power in FS See fixed station.
c
2000 by CRC Press LLC