# Contributions:DiffFilter

## Contents

## Synopsis

Take the derivative of a continuous time-series input wrt. time

## Location

http://www.bci2000.org/svn/trunk/src/contrib/SignalProcessing/HilbertSignalProcessing/DiffFilter.cpp

## Versioning

### Authors

Jeremy Hill

## Parameters

### DiffOrder

0 = disable; 1 = first derivative; 2 = second derivative; etc

### UnwrapDiff

Base at which to unwrap numerical deltas while computing the first derivative. 2*pi ( = 6.283185307179586232) would be the base appropriate for unwrapping phase differences. For example, HilbertFilter with OutputSignal=2 outputs instantaneous phase: when unwrapped at 2*pi, the first derivative of this yields 2*pi * instantaneous frequency.

### DivideByDeltaTime

Select whether to return raw sample-to-sample numerical deltas, or to divide these by the time delta in seconds to approximate a true derivative.

## States

None.

## See also

User Reference:Filters, Contributions:SignalProcessing, Contributions:HilbertSignalProcessing