DC Blocker
Block DC component
Library
Signal Operations
dspsigops
Description
The DC Blocker block removes the DC component of the input signal. This block supports SIMD code generation. For details, see Code Generation.
Dialog Box
The DC Blocker dialog box changes based on how the DC offset is estimated.
The dialog box for the IIR
method is shown below.
The dialog box for the FIR
method is shown below.
The dialog box for the CIC
method is shown below.
The dialog box for the Subtract mean
method is shown
below.
 Algorithm for estimating DC offset
Specify the algorithm used for estimating the DC offset. Select from the following:
IIR
uses a recursive estimate based on a narrow, lowpass elliptic filter. This algorithm typically uses less memory than FIR and is more efficient.FIR
uses a nonrecursive, movingaverage estimate. This algorithm typically uses more memory than IIR and is less efficient.CIC
uses a lowpass filter that does not employ any multipliers. If the algorithm isCIC
, then fixedpoint data must be input to the DC Blocker.Subtract mean
computes the means of the columns of the input matrix and subtracts the means from the input. This method does not retain state between inputs. For example, if the input is[1 2 3 4; 3 4 5 6]
, then the DC Blocker block inSubtract mean
mode outputs[1 1 1 1; 1 1 1 1]
.
 Normalized bandwidth of lowpass IIR or CIC filter
Specify the normalized filter bandwidth as a real scalar greater than 0 and less than 1. The DC Blocker uses this parameter only when the estimation algorithm is set to
IIR
orCIC
. Order of lowpass IIR elliptic filter
Specify the filter order as an integer greater than 3. The DC Blocker uses this parameter only when the estimation algorithm is set to
IIR
. Number of past input samples for FIR algorithm
Specify, as a positive integer, the number of samples to use when the estimation algorithm is set to
FIR
. View Filter Response
Opens the
fvtool
and displays the magnitude response of the DC Blocker. The response is based on the block parameters. Changes made to these parameters updatefvtool
.To update the magnitude response while
fvtool
is running, modify the block parameters and click Apply. Simulate using
Select the simulation type from the following:
Code generation
(default)Interpreted execution
Examples
Algorithms
This block implements the algorithm, inputs, and outputs described on the dsp.DCBlocker
reference page. The object properties correspond to the block
parameters.
Supported Data Types
Port  Supported Data Types 

Input 

Output 

References
[1] Nezami, M., “Performance Assessment of Baseband Algorithms for Direct Conversion Tactical Software Defined Receivers: I/Q Imbalance Correction, Image Rejection, DC Removal, and Channelization”, MILCOM, 2002.