PicoScope 3000A Series Prog rammer's Guide 15
Copyright © 2011-2013 Pico Technology Limited. All rights reserved. ps3000abpg.en r9
2.7.3
ETS (Equivalent Time Sampling)
ETS is a way of increasing the effective sampling rate of the scope when capturing
repetitive signals. It is a modified form of block mode, and is controlled by the trigger
functions and the ps3000aSetEts function.
Overview. ETS works by capturing several cycles of a repetitive waveform, then
combining them to produce a composite waveform that has a higher effective
sampling rate than the individual captures. The scope hardware adds a short,
variable delay, which is a small fraction of a single sampling interval, between each
trigger event and the subsequent sample. This shifts each capture slightly in time so
that the samples occur at slightly different times relative to those of the previous
capture. The result is a larger set of samples spaced by a small fraction of the
original sampling interval. The maximum effective sampling rates that can be
achieved with this method are listed in the User's Guide for the scope device.
Trigger stability. Because of the high sensitivity of ETS mode to small time
differences, the trigger must be set up to provide a stable waveform that varies as
little as possible from one capture to the next.
Callback. ETS mode calls the ps3000aBlockReady callback function when a new
waveform is ready for collection. The ps3000aGetValues function needs to be called
for the waveform to be retrieved.
Available in block mode only.
Not suitable for one-shot (non-repetitive) signals.
Aggregation is not supported.
Edge-triggering only.
Auto trigger delay (autoTriggerMilliseconds) is ignored.
Digital ports (on MSOs) cannot be used in ETS mode.
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