Closed chris-hld closed 7 years ago
Interesting. This should be fixed in #124
Imho, the documentation is wrong.
The documentation is in line with Schultz (2016), or do we have the same problem there that the values are defined differently? I'm also not sure if the equations in Verheijen (1997) and Start (1997) are different due to other definitions of the distances or if they are really different ;)
Does Schultz (2016) cover focused sources at all?
It doesn't, but as it should be only the time reversed version and |x0-xs|
and |xref-x0|
should be ok, as the sign does not matter.
If you do the math, especially the stationary phase approximation, there is a difference which stems from the time reversal. For the exponential term inside the synthesis integral you get exp(-j k (|x0 - xs| + |x0 - x|)) for a point source and exp(-j k (- |x0 - xs| + |x0 - x|)) for a focussed source. The second distance term |x0-x| is the green's function on the boundary and does not change with time reversal. The argument of the exponential directly corresponds to the denominator of g0.
OK, I have now tested it with test_wfs_25d()
and looked at the fact that the source in inside the listening area. Now, I would also say that the implementation is correct and the documentation is wrong. I will create a pull request for the documentation.
Nope
On 21 Dec 2016, at 8:10 PM, Fiete Winter notifications@github.com wrote:
Does Schultz (2016) cover focused sources at all?
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This is now fixed.
For 2.5-D WFS, getting the time based driving signals for a focused virtual source:
I tried both, and there is a difference in resulting amplitude. Which one should be preferred?