Page 51 - Electrical Engineering Dictionary

2. A controlled resistor (usually an FET analog signal a signal represented in a
operating in a triode regime) that is also part continuous form with respect to continuous
of the feedback circuit (the DC control signal time, as contrasted with digital signal repre-
is obtained with a rectifier and a filter of large sented in a discrete (discontinuous) form in
time constant). a sequence of time instant. See also analog
3. An automatic gain control circuit where data.
the DC control signal obtained from a recti-
fier and filter is used to change the bias of
analog signal conditioning an interface
oscillator active element.
between the sensor or transducer output,
whichrepresentsananalogorphysicalworld,
amplitude-modulatedlink atransmitter– and the analog-to-digital converter.
receiver system that utilizes amplitude-
modulation for the transmission of signal fre-
analog-to-digital (A/D) conversion a
quencies.
method by which a continuously varying sig-
nal (voltage) is sampled at regularly occur-
amplitude-shift keying (ASK) a mod-
ring intervals. Each sample is quantized to a
ulation technique in which each group of
discrete value by comparisons to preestab-
source bits determines the amplitude of the
lished reference levels. These quantized
modulated carrier.
samples are then formatted to the required
digital output (e.g., binary pulse code words).
AMPS See advanced mobile phone The A/D converter is “clocked” to provide
system. updated outputs at regular intervals. In order
not to lose any baseband information, sam-
AMR See automated meter reading. pling must occur at a rate higher than twice
the highest incoming signal frequency com-
analog See analog signal, analog data. ponent. See also Nyquist rate.

analog data data represented in a contin- analog-to-digital (A/D) converter a de-
uous form with respect to continuous time, vice that changes an analog signal to a digital
as contrasted with digital data represented in signal of corresponding magnitude. This de-
a discrete (discontinuous) form in a sequence vice is also called an encoder, ADC, or A/C
of time instant. converter.

analog multiplier a device or a circuit
analysis-by-synthesis coding refers to
that generates an analog output signal that is
the class of source coding algorithms where
proportional to the product or multiplication
the coding is based on parametric synthetiza-
of two analog input signals.
tion of the source signal at the encoder. The
synthesized signal is analyzed, and the pa-
analog optical computing optical com-
rameters that give the “best” result are cho-
puting that involves two-dimensional analog
sen and then transmitted (in coded form).
operations such as correlation and complex
Based on the received parameters the signal
spatial frequency filtering primarily based
is resynthesized at the receiver.
on the property of lens to perform two-
dimensional Fourier transform. In analog
optical computing, operations to be per- analysis filter a filter in the analysis sec-
formed are matched with and based on al- tion of a sub-band analysis and synthesis sys-
ready known optical phenomena. tem.

c
2000 by CRC Press LLC