*From*: Andreas Rossbacher <andreas.rossbacher@xxxxxxx>*To*: kismac@xxxxxxxxxxxxx*Date*: Thu, 12 Jun 2003 18:51:45 +0200

-----BEGIN PGP SIGNED MESSAGE----- Michael Rossberg wrote: > i have a question about your decline algorithm. > > result=1/this.getDistance(x,y,i) * Math.sqrt((rField/(4 * Math.PI)) * > scatterPoint[i].getValue()); > result=result / scatterPoint[i].getValue(); > > how should this work? if this derived from the surface area of a > sphere, then should this be not decline = rField / ( distance^2 * 4 * > Pi ). why did you take the square root? > and what about correction to dbm? I used the calculation for a E-Field using the scatterPoint as an "virutal" antenna and the measured signal strength there as its power. To calculate the E-Field your use: E = 1/r sqrt( (Z_0 / (4 PI) ) P_rad) better to visualize in TeX: $E = \frac{1}{r} \sqrt{\frac{Z_{0}}{4\pi}\cdot P_{rad}}$ Z_0 is the field wave resistance of empty space which shall be 377 Ohm. P_rad is the radiatin power which is set equal to the measured data at the scatter point. So if i have the Power in mW at the scatter points i can calculate the decline factor here. You can easyly convert dbm to mW by: mW = 10^(dbm/10) Anyway, this is not my realm. :-) If i did something stupidly wrong, hit me! *g* After finishing my decline algorithm i though thougt it might be much to difficult cause the radiation simply declines with the square over the distance. But that is cause of it having to spread a much wider area on the surface of the sphere of the antenna. No normal field wave resistance is used then. - -- bye Andreas -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.1-nr1 (Windows XP) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iQDVAwUBPuivoTkz2wj/y23tAQGQZAYAur6z9N3Q1RK7WPVY5oIoA2YtJWJjuXv4 oT7T4jcAN4gcpx9R/qk1XQCNkjAYYvds34wgErtWEb6zfWnYHvSSo1V26ygmg8KD Dm9beqEUFL+7oCqfTjiOU/zR1ZQA+VX3kq7JjslcMYkiriqnmtwoWtxfOVBfeUJ+ UX6nBBUcIrIheOKsR0XYFFS7x7Xmhyre0GKEaRq+lHvo8K59Odwbz/EEKY+kFygx /qpjYyu7+u6Dj8U7J4ozJriiQ1YHqZvo =U/Dc -----END PGP SIGNATURE-----

**References**:**[kismac] Re: Net Area Power Interpolation***From:*Michael Rossberg

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