%% DC Blocker with Fixed Point Data
% This example shows how to use the DC Blocker to remove a DC offset from fixed point data.
% Load the DC Blocker example by typing ex_dcblock_cicmode in the MATLAB command prompt.
% In the model:
% 64-QAM data passes through an AWGN channel.
% A DC offset of 1 is added to the signal .
% The Double -> Fixed block converts the data to 16-bit fixed point.
% The fixed-point data passes through the DC Blocker, which has the CIC algorithm selected, to remove the DC offset.
% The Fixed -> Double block converts the data back to floating point.
% Constellation diagrams and spectrum analyzers are used to show the improvements from the DC Blocker.
%
% Run the simulation. The first constellation diagram, Noisy Constellation, shows a 64-QAM signal with white noise.
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% Observe the constellation diagram of the signal after the DC offset of 1 has been applied. The signal, represented by the yellow data points, has shifted one unit to the right.
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% Look at the spectrum of the noisy signal with the DC offset. Notice that the signal has a peak at 0 Hz.
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% Observe the noisy constellation after the DC offset is removed. The signal has shifted back to the left so that the data clusters are aligned with their corresponding reference points.
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% Observe the spectrum of the noisy signal after the DC Blocker removes the offset. The spectral peak at 0 Hz has been removed.
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% To visualize the efficiency of the DC Blocker under different conditions, try changing the DC offset or the Normalized bandwidth of lowpass IIR or CIC filter parameter.
% Copyright 2012 The MathWorks, Inc.