:ACQuire:SMODe

Command Syntax

:ACQuire:SMODe  {NORMal | AVERage}

Query Syntax

:ACQuire:SMODe?

Description

Sets the acquisition sampling mode:

• NORMal — Individual acquisitions are displayed and measured.
• AVERage — Acquisitions are averaged until the specified number of waveforms has been acquired (see :ACQuire:COUNt, also known as the terminal count); then, the averaged waveform is measured. This is true for single acquisitions or continuously running acquisitions. Status information on the display to the right of the waveform tab shows how many waveforms have been averaged.

Use acquisition averaging in the following instances:

• Use only with repetitive waveforms.
• Use to eliminate random noise.
• Use to improve vertical resolution.
• Use to improve measurement repeatability.

Do not use acquisition averaging for:

• Non-repetitive waveforms, as very inaccurate results can occur.
• Improperly triggered waveforms, as the input waveform may be asynchronous to Infiniium and will average to zero over time even though a non-zero input waveform is being measured.

When acquisition averaging is on, waveforms are acquired from multiple data acquisitions and then averaged together, point by point. The noise sources can average to zero over time while the underlying waveform is preserved. The effective resolution of the displayed waveform increases as more acquisitions are averaged together, provided that the input waveform is repetitive and has a stable trigger point. This improves the stability of both the display and waveform measurements.

When acquisition averaging is selected, use the :ACQuire:COUNt command to set the number of waveforms that you want to use in the calculation. You can enter a value between 2 and 1M. The default value for the number of averages is 16.

For acquisitions up to the specified number of acquisitions to be averaged (for 1 ≤ n < M), the following formula is used to calculate the average for each data acquisition, point-by-point:

After terminal count is reached (n ≥ M), this formula is used to calculate the average or each data acquisition, point-by-point:

where:

• Ave_n = the average sample value.
• n = the current average number.
• M = Number of Waveforms control setting (terminal count).
• S_i = the i^th sample (for the n^th sample, S_i = S_n).

Example Command Sequence

:ACQuire:SMODe AVERage
:ACQuire:COUNt 32