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bus. A data-carrying electrical pathway.
Chart. An application supplied with a
PowerLab that emulates a multi-channel
chart recorder, with other powerful options.
(Macintosh and Windows versions differ.)
connector. A plug, socket, jack, or port used
to connect one electronic device to another
(via a cable): a PowerLab to a computer, say.
CPU (central processing unit). A hardware
device that performs logical and arithmetical
operations on data as specified in the
instructions: the heart of most computers.
DAC (digital-to-analog converter). A device
that converts digital information into some
corresponding analog voltage or current.
DC offset. The amount of DC (direct current)
voltage present at the output of an amplifier
when zero voltage is applied to the input; or
the amount of DC voltage present in a
transducer in its equilibrium state.
differential input. Input using both positive
and negative inputs on a PowerLab. The
recorded signal is the difference between the
positive and negative input voltages: if both
were fed exactly the same signal, zero would
result. Can reduce the noise from long leads.
digital. Varying discretely. A digital signal
changes to discrete values rather than
varying continuously. A digital time display
might read 2:57 instead of using the positions
of a pair of hands on a clock face.
DIN (Deutsche Industrie Norm). A sort of
cable or connector; there are various sorts
with different numbers of pins.
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envelope form. The overall shape of a signal,
outlined by the minimum and maximum
recorded values. Often used to display
quickly changing signals.
excitation voltage. The voltage supplied to a
bridge circuit from which the transducer
output signal is derived. Manipulating the
transducer changes the measurement
elements of the bridge circuit, producing a
change in its output voltage.
external trigger. The input connector on the
front of the PowerLab marked 'Trigger'. This
lets one start recording from an external
source. The trigger level (the voltage needed
to have an effect) depends on the hardware
and cannot be changed. The /20 series
PowerLabs can also be triggered by contact
closure if this is set up in the software.
filter. An electronic device or a program that
alters data in accordance with specific
criteria. Filters in hardware and software can
be used to reduce or to eliminate electronic
noise or drift from data readings.
frequency. The number of complete cycles
per second of a waveform. Frequency is
usually expressed in hertz, Hz (cycles per
second), kilohertz, kHz (thousands of cycles
per second), or megahertz, MHz (millions of
cycles per second).
frequency response. The bandwidth in
which a circuit passes a signal without too
much attenuation. A low-pass filter's
frequency response is the frequency where
the output voltage becomes 0.707 (1/√2) of
the input voltage or has been attenuated by 3
decibels. If a low-pass filter has a frequency
response of 200 Hz, say, then the signal is
PowerLab Owner's Guide
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