Instruction manual

AMPDIO DRIVERS
Page 240
APPENDIX A GLOSSARY OF TERMS
The following glossary explains some terms used in this manual and in data acquisition and control applications.
Active Filter: An electronic filter that combines active circuit devices with passive circuit elements such as resistors
and capacitors. Active filters typically have characteristics that closely match ideal filters.
ADC (A/D): Analog to Digital converter. q.v.
Alias Frequency: A false lower frequency component that appears in analog signal reconstructed from original
data acquired at an insufficient sampling rate.
Algorithm: A set of rules, with a finite number of steps, for solving a mathematical problem. An algorithm can be
used as a basis for a computer program.
Analog to Digital Converter (ADC): A device for converting an analog voltage to a parallel digital word where the
digital output code represents the magnitude of the input signal. See ‘Successive Approximation’.
Analog Switch: An electronic, single pole, two way switch capable of handling the full range of analog signal
voltage, and operating under the control of a logic signal.
Array: Data arranged in single or multidimensional rows and columns.
ASCII: American Standard Code for Information Interchange. A code that is commonly used to represent symbols in
computers.
Assembler: A program that converts a list of computer instructions written in a specific assembly language format
that can be executed by a specific processor.
Bandpass Filter: A type of electrical filter that allows a band of signals between two set frequencies to pass, while
attenuating all signal frequencies outside the bandpass range.
Base Address: A unique address set up on an I/O card to allow reference by the host computer. All registers are
located by an offset in relation to the base address.
BASIC: The most common computer language. BASIC is an acronym for Beginners All-purpose Symbolic
Instruction Code. BASIC is not rigorously structured and relies on English-like instructions which account for its
popularity.
Binary Coded Decimal (BCD): A system of binary numbering where each decimal digit 0 through 9 is represented
by a combination of four bits.
BIOS: Basic Input Output System. BIOS resides in ROM on a computer system board and provides device level
control for the major I/O devices on the system.
Bipolar: A signal being measured is said to be bipolar when the voltage on its 'high' terminal can be either of
positive or negative polarity in relation to its 'low' terminal.
Bit: Contraction of binary digit. The smallest unit of information. A bit represents the choice between a one or zero
value (mark or space in communications technology).
Buffer: A storage device used to compensate for a difference in rate of data flow, or time of occurrence of events,
when transferring data from one device to another. Also a device without storage that isolates two circuits.
Bus: Conductors used to interconnect individual circuitry in a computer. The set of conductors as a whole is called
a bus.
Byte: A binary element string operated on as a unit and usually shorter than a computer word. Normally eight bits.
C: A high level programming language, developed around the concept of structured programming and designed for
high operating speeds. Microsoft 'C' and Turbo 'C' are dialects of C.
Channel: One of several signal/data paths that may be selected.
Character: A letter, figure , number, punctuation or other symbol contained in a message or used in a control
function.
Code: A set of unambiguous rules specifying the way in which characters may be represented.
Conversion Time: The time required for a complete conversion of a value from analog to digital form (ADC) or
analog to digital form (DAC). Inverse of Conversion Rate.
Cold Junction: See Thermocouple Reference Junction
Cold Junction Compensation (CJC): A technique to compensate for thermocouple measurement offset when the
reference or cold junction is at a temperature other than 0° C.
Common Mode Rejection Ratio (CMR): A measure of the equipment's ability to reject common mode interference.
Usually expressed in decibels as the ratio between the common mode voltage and the error in the reading due to
this common mode voltage.