Category: Statement

Syntax: detect <expression>

Description

Detect statement has four functions. It is used to:

• trigger the acquisition system using pulse command detect.
• define the number of acquisition channels.
• apply the acquisition coefficients for the channels used.
• determine the phase of the carrier frequency for direct digital detection.

As a PPL statement detect has a zero duration (internal time counter is not modified). Multiple detect commands can be present in a single script. The number of expected triggers can not be determined during runtime and should be provided in Pulse Script Editor.

For digital detection engine timezero defines the phase of the detect statement calculated as frequency*(detect_time - t0) where frequency is defined by reference statement and t0 set by timezero statement.

The number of arguments defines the acquisition channels, which can be chosen from the list in the signal declaration. The number of arguments has to be smaller than or equal to the number of signal variables declared. Detection coefficients will be multiplied to the values of recorded transient data. In the simplest case of phase cycling, those coefficients are +1 and -1.

Example:

int phidx %% Parameter declaration (indices 1 or 2) signal a, b %% Detection channels declaration p1 = [+a, -b] %% Detection array definition ('+' is not required) p2 = [-a, +b] %% Detection array definition detect p1(phidx), p2(phidx) %% Two-channel detection for different phases

Legend: PPL keywords; PPL pulse commands; comments.