Question of units of dBu

[onoahimahi]

Hello,

I am a new Proplab user with interest in over-the-horizon radar. I have a question on the signal level units reported by Proplab of dBu – what is it and how do I convert it to watts?

Thanks,
-Scott

[admin]

You can learn all about dBu and how to convert it to Watts or volts, etc, by going to:
http://en.wikipedia.org/wiki/Decibel#Electric_voltage

[onoahimahi]

That site gives two definitions of dBu both of which appear to differ from how Problab is defining it.  By playing around a little, I get what looks like the right answer in dBWatts when I subtract 120 dB from what Problab is calling dBu. What confused me was that Proplab apperently is not accounting for the 377 ohm impedance of free space.  Thus if you wanted to convert what Proplab is calculating to what an observer would measure with a field strength meter reporting dBuV/m, you would have to subtract 10log(377). Did I miss something? 

Thanks,
-Scott