Phase Detector


Detailed: LSP Phase Detector (PD1)


Categories: Analyser

Developer: Vladimir Sadovnikov


This plugin allows to detect phase between two sources. For example, for two or more microphones set at the different positions and distances from the sound source.

The internal algorithm is based on correlation function calculation between two sources.

Be aware: because there are many correlation functions for different phases calculated at one time, the entire analyzing process can take a lot of CPU resources. You can also reduce CPU utilization by lowering the maximum analysis time.

The plugin bypasses input signal without any modifications, so it can be placed everywhere it's needed.



The Correlation Graph is two-dimensional graph that allows to monitor immediate values of the set of correlation functions. The horizontal axis is the relative time offset, the vertical axis is the normalized correlation function value. The thick blue line shows the normalized values of the set of correlation functions depending on the time offset. The values of the Best, Selected and Worst meters are drawn as crossing lines with the matching colors.

When the signal from the left (A) channel comes with delay relatively to the right (B) channel, the offset values will be positive. When the signal from the B channel comes with delay relatively to the A, the offset values become negative. In most cases, when sources are in phase, the Value indicator for the Best row takes the value near to 1, otherwise the Value indicator of the Worst row takes value near to -1, so for correctly phasing two sources the phase for one of the sources has to be inverted. Two sources are in-phase when the Value of the Best row shows 1 and other columns (especially Offset) show the values near to the 0 the most time.