Hello all, this is a formula that calculates DDM (depth of modulation) at certain outputs of the ILS's Glideslope. I posted this question some time ago but I think I left out some important details. Any help is really appreciated.(adsbygoogle = window.adsbygoogle || []).push({});

This is basic info on the ILS

http://en.wikipedia.org/wiki/Instrument_Landing_System

db = 20log(E1/E2)

E1 is the input voltage before attenuation

E2 is the output voltage after attenuation

E1 and db seems like is always given. E2 is what needs to be solved.

My course book rearranges the formula to this: E2 = E1log-1(db/20)

-that makes NO sense to me. Log to negative power - or the reciprical?

this is one of the examples they have:

db = -3

E1 = .155

E2 = .155log-1(-3/20) = 0.109

more examples:

2.5log-1(-3/20) = 1.77

1.0log-1(-3/20) = 0.707

.494log-1(-3/20) = 0.342

Is there another way to rearrange the formula that makes sense?

Thank you.

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# Homework Help: Problem with formula - please help.

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