Remove steps of adjacent points

Hi,

I have a signal which shows repeating lower peaks due to end point and new starting point being on a different level. What is the fastest and easiest way to remove the step/peak and lift all points to the right in such a way that the two connecting points are on the same level and the rest of the signal is lifted with the same amount.

Thanks.

Answer 1

[Matt J]

Perhaps as follows:

threshold=0.5;

t=0:0.01:3;
signal=log(mod(t,1)+1);

D=diff(signal(:).');

D(abs(D)>threshold)=0;

signal2=cumsum([signal(1),D]);


plot(t,signal, '-x',t,signal2); legend('Original','Modified')

[Matt J]

If the jumps are occuring at known intervals N, you could also do,

D=diff(signal(:).');

D(N:N:end)=0;

signal2=cumsum([signal(1),D]);

Answer 2

[Image Analyst]

You said you have "lower peaks due to end point". So it's always the last point that drops. So the last point is bogus and should basically be ignored? Are you obtaining a sequence of signals, And then you just stitch on the next signal onto the master, growing signal? So you could do

allSignals = [];
for k = 1 : numberOfSignalsToStitch
    thisSignal = HoweverYouGetIt();
    % Crop off/ignore last element.
    thisSignal(end) = [];
    if k == 1
        allSignals = thisSignal;
    else
        % Put first point where last point is
        thisSignal = thisSignal - thisSignal(1) + allSignals(end);
        % This will "lift" the current signal to the end of the last signal.
        allSignals = [allSignals, thisSignal]
    end
end

If you need more help, attach your signal(s) in a .mat file.

[Konvictus177]

It is the new starting point that is on a lower level than the last point. So the new starting point would we bogus. This new starting point should not be removed but be on the same level as the last point like a straight line connection. All points after the first point should be lifted with the same amount the first point is lifted to make the straight connection.