MATLAB: How to straighten a sinusoidal signal

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I have a signal that bouncy (the waves are all over the place), and I've been trying to filter out the bouncy signals without changing the amplitude of the whole signal. Basically, I'd like a sinusoidal signal that is somewhat straight (doesn't have to be perfect). The data from the signal was imported from an excel file.
I have attached an image of what one of my signals look like. The problem with that particular signal is that little dip at the end of the signal that is very uneven with the rest of the waves.
Thanks for your help!

Best Answer

It looks like the signal is going along just fine until suddenly there is a big jump, and then it's fine again. So rather than filter the whole signal, I'd just identify the jump locations, determine the new offset, and subtract that from the signal. Here is the code. It's s fast and simple for loop.
% Initialization steps.
clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;
xy = xlsread('capture 2.xls');
x = xy(:, 1);
y = xy(:, 2);
subplot(3, 1, 1);
plot(x, y, 'b-');
grid on;
title('Original Signal', 'FontSize', fontSize);
subplot(3, 1, 2);
differences = [0; diff(y)];
plot(x, differences, 'b-');
grid on;
title('Difference Signal', 'FontSize', fontSize);
offset = 0;
for k = 1 : length(y)
  if abs(differences(k)) > 0.001
    offset = differences(k);
  end
  correctedSignal(k) = y(k) - offset;
end
subplot(3, 1, 3);
plot(x, correctedSignal, 'b-');
title('Corrected Signal', 'FontSize', fontSize);
grid on;
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0, 0.04, 1, 0.96]);
I think it does a pretty good job, don't you?
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