DC Blocker

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A computationally efficient controllable DC blocker that blocks the DC component of a signal. This can be useful when working with AM signals, as taking the magnitude of the envelope will always be positive and thus introduce a DC bias on the signal.

This block implements a computationally efficient DC blocker that produces a tighter notch filter around DC for a smaller group delay than an equivalent FIR filter or using a single pole IIR filter (though the IIR filter is computationally cheaper).

The block defaults to using a delay line of length 32 and the long form of the filter. Optionally, the delay line length can be changed to alter the width of the DC notch (longer lines will decrease the width).

The long form of the filter produces a nearly flat response outside of the notch but at the cost of a group delay of 2D-2.

The short form of the filter does not have as flat a response in the passband but has a group delay of only D-1 and is cheaper to compute.


Specifies the length of the delay line used for determining the DC level. Only applicable to the long form.
Long Form
When set to True, use the long form DC blocker, with delay line. When set to False, use the short form (faster).

Example Flowgraph[edit]

Insert description of flowgraph here, then show a screenshot of the flowgraph and the output if there is an interesting GUI. Currently we have no standard method of uploading the actual flowgraph to the wiki or git repo, unfortunately. The plan is to have an example flowgraph showing how the block might be used, for every block, and the flowgraphs will live in the git repo.

Source Files[edit]

C++ files
Header files
Public header files
Block definition