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APPENDIX
H
Complex
Waveform-A
periodic waveform made up of a
combination
of several frequencies or several sine waves
superimposed
on one another.
Controller-A
device which governs the operation of the
IEEE-488 bus; generally a controller is a small computer
or microcomputer.
Conversion-A
single piece of binary
data that is the
result of the A/D converter transformation
process. A
conversion
is one sample.
Count-The
minimum
step size that
an instrument
display
can resolve. Display
size is often defined
in
counts, as in a 32,767 count display.
Crosstalk-Unwanted
coupling of a signal from one chan-
nel to another by conduction
or radiation.
CRT-Cathode
Ray Tube. A term generally
used when
referring
to a computer
or terminal
display screen.
Cursor-A
flashing
display digit or segment used to in-
dicate the next digit affected by data entry.
DAC-Abbreviation
for Digital-to-Analog
Converter.
A
device which converts digital or binary information
into
an analog signal.
Data
Entry-The
process of keying in data from the front
panel using the numeric keys.
dS-Abbreviation
for decibel, which is a logarithmic
unit
used to measure and compare voltage, current,
and
power levels.
Differential
Non-linearity-The
maximum deviation of an
actual quantized
step width
from the ideal quantized
step.
Digital-Circuitry
in which the data-carrying
signals are
restricted
to one of two voltage levels. These voltage
levels are used to represent the binary values 1 and 0.
Digitize-To
convert
an analog signal into a series of
binary numbers representing
its amplitude
at discrete
intervals of time.
DMA-Abbreviation
for Direct Memory Access. A method
where digital bytes or words are stored in or accessed
from memory locations directly without requiring micro-
processor intervention.
DMA is generally
faster than
other forms of memory access.
Earth Ground-A
connection
from an electrical circuit or
instrument
to the earth through
a water pipe or metal
rod driven into the ground.
H-2
EMI-Abbreviation
for Electromagnetic
Interference.
A
term that defines unwanted
electromagnetic
radiation
from a device which could interfere with desired signals
in electronic receiving equipment such as television and
radio. RF1 (Radio Frequency Interference)
and EM1 are
often used interchangeably.
Fourier
Series-A
mathematical analysis that permits any
complex waveform to be resolved into a fundamental,
plus a finite number of terms involving
its harmonics.
GPIB-Abbreviation
for General Purpose Interface BUS.
Another
term for the IEEE-488 bus.
Hexadecimal-A
number system based on the number 16
that uses values O-9, and A through F to represent the
16 possible values of a 4.bit binary number. Hexadecimal
numbers are represented by preceding them with a $ or
following them with a letter H. Thus, $7F and 7FH would
be equivalent.
High
Speed-Pertaining
to the instrument's
ability to take
a large number of samples in a short period of time.
IC-Abbreviation
for Integrated Circuit. A combination
of
interconnected circuit elements inseparably contained on
or within
a single substrate.
IEEE-488
Bus-A
parallel instrumentation
data and con-
trol bus standardized
by the Institute
of Electrical and
Electronic Engineers.
Integral
Reading-A
reading in volt-seconds that defines
the approximate
area under a cuwe bounded
by the
amplitude
of the samples and the time duration
of the
measurement.
I/O-Abbreviation
for input/output,
which refers to the
transmission
of information
from an instrument
to an
external device (output),
or the transfer of information
from an external device to an instrument
(input).
K-Abbreviation
for kilo. In computer
terms, lK equals
1024. For example, a 16K byte memory has 16,384 bytes.
LED-Light
Emitting
Diode. A PN junction
diode that
emits light when forward biased. LEDs are used in front
panel annunciators
as well as the individual
segments
of numeric
displays on instrumentation.
Listener-A
device
which,
when
connected
to the
IEEE-488 bus, is capable if receiving information
over that
bus.
Measurement-A
group
of raw
samples,
stored
in
memory, that are not mathematically
processed in any
WY.
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