I'm working with an ECG program that takes the ECG signal from the DAQ and saves the first Signal so the rest of the signals after that have something to compare and reference against.
My question is, whats the best way to compare these signals so that if one of the signals skews off of the reference signal some sort of alarm will go off and let me know something is wrong. I was thinking of using maybe an intergral function to compare the 2 signals but was just wondering if there was a better or more accurate way to compare?
Maybe you could take the data points and add/subtract some limit amount to make an upper limit array and a lower limit array. Then compare the array of data points taken from the ECG against the array of limits. That would take care of amplitude check. However, there may be jitter, where the p-wave starts slightly before or slightly after the sample p-wave. You would have to adjust the comparison index plus or minus a few elements. This is going to be tricky.
I use the mask functions (Waveform>Analog Waveform>Waveform Measurements>Waveform Monitoring) to compare a signal to a standard. The standard I use though, is defined by a formula that I can plug in an use. I have never tried to create a mask from an acquired signal. Maybe someone else has. It might be worthwhile to search the forum for mask testing or ask a new question about that. The other option might be to create the mask from an ideal waveform. If you can describe an upper and lower limit mathematically, you can use those plots for the mask test.
Here is a crude excel file with graph that shows the data plus upper and lower limits. I don't have time to play with it further. The trick is to mathematically create the limits. I'm sure if you played with it a little, you could come up with something.
