ADInstruments PowerLab 30 Series Owner's Manual page 43

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/Ð2) 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 effectively unattenuated up to 150 Hz, and is
0.707 of the original value at 200 Hz.
front-end. An ancillary device that extends PowerLab capabilities, providing
additional signal conditioning and features for specialized work. Front-ends
are recognized automatically by the PowerLab system and seamlessly
integrated into its applications, operating under full software control.
gain. The amount of amplification of a signal.
half-bridge transducer. A bridge transducer only using half of the full-bridge
circuit. It consists of two elements of equal value with an excitation voltage
applied across them. The output of the transducer is taken at the junction of
the two elements.
hertz (Hz). The unit of frequency of vibration or oscillation, defined as the
number of cycles per second. For example, the minimum sampling rate for a
human ECG experiment should be 400 Hz (400 samples/s).
high-pass filter (HPF). A filter that passes high-frequency signals, but filters
low ones, by blocking DC voltages and attenuating frequencies below a certain
value (the cut-off, or –3 dB, frequency).
2
I C ('eye-squared-sea'). This connection is used by the PowerLab to control
front-ends. It provides power and communications using a
2
4-wire serial bus (two wires for standard I C and two control lines).
IEC. International Electrotechnical Commission.
LabChart. An application supplied with a PowerLab that emulates a multi-
channel chart recorder, with other powerful options. (Macintosh and
Windows versions differ slightly.)
LabTutor. An ADInstruments application for teaching physiology that
integrates the experiment protocol, real-time data acquisition, analysis and
reporting as interactive pages in the Internet Explorer browser.
low-pass filter (LPF). A filter that passes low-frequency signals and DC
voltages, but filters high ones, attenuating frequencies above a certain value
(the cut-off, or –3 dB, frequency).
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Glossary