## Research Fig.20:

Wave resulting from a random (i.e. incoherent) superposition of 500 wavetrains each with a length of 10 cycles and constant amplitude=1 within a total range of 50 cycles.

The effective coherence length of the resulting signal A(φ) was calculated by

Φ_{coh} = 4/π/|A|_{av} ^{.}_{0}∫^{φmax}dφ A(2πφ)^{.}[sin(2πφ)+cos(2πφ)] [cycles] ,

where |A|

_{av} is the average absolute value of the amplitude.

The result shows that the coherence length of the total wave field is essentially identical (to within statistical accuracy) with the coherence length of the individual wavetrains.