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find pulsed trigger events

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The function finds the start of pulsed events in a signal via a trigger limit.



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I had the problem of needing to find an unknown number of pulses in a signal, but I knew the pulse rate and the approximate length of the pulses (but there could be some missing). This function has a trigger with downtime functionality and will find all events with a given trigger level.

% Example 1
% generate signal with two pulses of random noise:
sig = [zeros(1,200) .5-rand(1,20) zeros(1,200) .5-rand(1,20)];
fs = 440;
level = .02;
prate = 2;
triggerindex = get_trigger(sig, level, fs, prate, 'r');
% make it visible:
plot(sig); hold on
plot(triggerindex, sig(triggerindex), 'or')

I wrote this some time ago and I know it could be made more efficient, but for the signal lengths I'm dealing with it works okay. But feel free to post some improvements.

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MATLAB 7.11 (R2010b)

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