Category: Statement

Syntax: detect <expression>

Description

Detect statement has four functions. It (i) triggers the acquisition system using pulse command detect; (ii) defines the number of acquisition channels; (iii) applies the acquisition coefficients for the channels used; and (iv) specifies the phase of 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.

Number of arguments defines the acquisition channels, which can be chosen from the list in the signal declaration. Number of arguments has to be smaller or equal to amount of signal variable declared. Detection coefficients are values of which all transient data recorded after the execution of PPL will be multiplied. In the simplest case of phase cycling those coefficients are +1 and -1.

Example:

int phidx %% Parameter declaration (1 or 2) signal a, b %% Detection channels declaration p1 = [+a, -b] %% Detection array definition p2 = [-a, +b] %% Detection array definition detect p1(phidx), p2(phidx) %% Two-channel detection for different phases

Legend: PPL keywords; PPL pulse commands; comments.