User Manual

PicoScope 4000 Series User's Guide 17

4 Glossary

AC/DC switch. To switch between AC coupling and DC coupling, select AC or DC

from the control on the PicoScope toolbar. The AC setting filters out very low-

frequency components of the input signal, including DC, and is suitable for viewing

small AC signals superimposed on a DC or slowly changing offset. In this mode you

can measure the peak-to-peak amplitude of an AC signal but not its absolute value.

Use the DC setting for measuring the absolute value of a signal.

Analog bandwidth. The input frequency at which the measured signal amplitude is 3

decibels below the true signal amplitude.

Buffer size. The size of the oscilloscope buffer memory, measured in samples. The

buffer allows the oscilloscope to sample data at a fast sampling rate before

transferring the data to the computer at a slower rate. Once the buffer fills up, the

scope must stop sampling, so on longer time bases the buffer size places an upper

limit on the sampling rate that can be used.

IEPE Interface Mode When in this mode the connected probes are powered by a

current from the two BNC IEPE connectors.

Integrated Circuit Piezoelectric (ICP

Registered to the PCB Group

). See IEPE.

Integrated Electronics Piezoelectric (IEPE). An industry standard for

accelerometers and other sensors with built-in electronics. IEPE connections use a DC

current to power a small pre-amplifier embedded in the probe, enabling the use of

long cables without a remote power supply. 'ICP' is one of several proprietary names

for the same system.

Equivalent-time sampling (ETS). A specialised sampling mode that can be used to

increase the effective sampling rate of an oscilloscope as long as the signal is a stable,

repetitive waveform. A single sample is collected during one cycle of the waveform.

The scope then re-arms and re-triggers on another cycle of the waveform, and

collects another sample with a slight time offset relative to the previous one. Over a

large number of cycles, enough samples are collected to display a high-resolution

picture of the waveform. Also called sequential sampling.

GS/s. Gigasamples (billions of samples) per second.

Maximum sampling rate. A figure indicating the maximum number of samples the

oscilloscope can acquire per second. The higher the sampling rate of the oscilloscope,

the more accurate the representation of the high-frequency details in a fast signal.

"MS/s" is an abbreviation for megasamples (millions of samples) per second.

MS/s. Megasamples (millions of samples) per second.

Oversampling. The process of taking measurements more frequently than the

requested sample rate, and then combining them to produce the required number of

samples. If, as is usually the case, the signal contains a small amount of noise, this

technique can increase the effective vertical resolution of the oscilloscope.

PC Oscilloscope. A virtual instrument formed by connecting a PicoScope 4000 Series

oscilloscope to a computer running the PicoScope software.

PicoScope 4000 Series. Pico Technology's high-resolution PC Oscilloscopes.