PicoScope 2000 Series Programmer's Guide 59
Copyright © 2006–2016 Pico Technology Ltd. All rights reserved. ps2000pg.en r11
8 Glossary
Aggregation. In fast streaming mode, the PicoScope 2000 driver can use a method
called aggregation to reduce the amount of data your application needs to process.
This means that for every block of consecutive samples, it stores only the minimum
and maximum values. You can set the number of samples in each block, called the
aggregation parameter, when you call ps2000_run_streaming_ns for real-time
capture, and when you call ps2000_get_streaming_values to obtain post-
processed data.
Analog bandwidth. The input frequency at which the signal amplitude has fallen by 3
dB, or by half the power, from its nominal value.
Block mode. A sampling mode in which the computer prompts the oscilloscope to
collect a block of data into its internal memory before stopping the oscilloscope and
transferring the whole block into computer memory. This is the best mode to use when
the input signal being sampled contains high frequencies. To avoid aliasing effects, the
sampling rate must be greater than twice the maximum frequency in the input signal.
Buffer size. The size of the oscilloscope's buffer memory. The oscilloscope uses this to
store data temporarily so that it can sample data independently of the speed at which
it can transfer data to the computer.
Coupling mode. This mode selects either AC or DC coupling in the oscilloscope's input
path. Use AC mode for small signals that may be superimposed on a DC level. Use DC
mode for measuring absolute voltage levels. Set the coupling mode using
ps2000_set_channel.
Driver. A piece of software that controls a hardware device. The driver for the
PicoScope 2000 Series PC Oscilloscopes is supplied in the form of a 32-bit Windows
DLL, which contains functions that you can call from your application.
ETS. Equivalent time sampling. Some PicoScope 2000 Series oscilloscopes can collect
data over a number of cycles of a repetitive waveform to give a higher effective
sampling rate than is possible for a single cycle. Equivalent time sampling allows the
oscilloscope to use faster timebases than those available in real-time mode.
Maximum sampling rate. A figure indicating the maximum number of samples the
oscilloscope is capable of acquiring per second. Maximum sample rates are usually
given in MS/s (megasamples per second) or GS/s (gigasamples per second). The
higher the sampling speed of the oscilloscope, the more accurate the representation of
the high-frequency details in a fast signal.
Oversampling. A method of increasing the effective resolution of a measurement by
sampling faster than the required sampling rate, then averaging the extra samples. An
oversampling factor of four increases the effective resolution by one bit, but this
increased resolution comes at the expense of reducing the maximum sampling rate by
the same factor.
Overview buffer. A buffer in the PC's memory in which the PicoScope 2000 Series
driver temporarily stores data on its way from the oscilloscope to the application's
buffer.
PC Oscilloscope. A virtual instrument consisting of a PicoScope PC Oscilloscope and a
software application.
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