Hi DFGray,
This is brilliant.... Just what I needed... Thank you very much.
Whilst on the topic of EMG MDF, I wonder if you have ever heard of the EMG "spectral distribution functrion" to determine "sprectral compression"? I have a attached a paper cut n paste to relevant text below:
2.2.2. Measures of spectral compression
Measures of spectral compression were calculated for
each epoch for signal A1 (Fig. 2). The Spectral Distribution
Function (SDF) is defined as the normalised integral
of the amplitude spectrum of a signal, Fig. 3, [18].
It is similar to the cumulative power function described
by Lateva [10] and Merletti and Lo Conte [21] but is
derived from the EMG amplitude spectrum rather than
the power spectrum. From the SDF, the location of all
percentile frequencies may be calculated. The results
presented in [18] indicate that compression of the EMG
amplitude spectrum is not uniform at all frequencies.
The compression is most uniform in the region of the
spectrum lying between the 60th and 90th percentiles.
The SCE was therefore defined as the mean shift, with
respect to the first epoch, in all percentile frequencies
between the 60th and 90th, (0.6 SDF 0.9) i.e. the
mean value of the ratio of f2 to f1 in this region, Fig. 3.
The mean value was calculated to reduce the effects of
noise. The median frequency of the EMG amplitude
spectrum was also calculated i.e. the frequency at the
50th percentile (SDF 0.5), Fig. 3. The median frequency
of the EMG power spectrum was similarly calculated.
How would could amend your EMGAnalysis.vi to calculate EMG Amplitude Spectrum compression between the 60th and 90th percentiles?
Thanks,
Jack
