Electronics > Beginners
converting Volt into dB
soldar:
--- Quote from: NaxFM on August 07, 2019, 02:44:57 pm --- You can't have a negative gain, the gain is always positive, less than one if it's an attenuation, more if it's a gain.
--- End quote ---
I don't think that's right. https://en.wikipedia.org/wiki/Decibel shows negative numbers. 0 dB is gain of unity. Negative gains get negative numbers in dB. WIFI ranges in the -60 dB range. Audio too.
NaxFM:
--- Quote from: soldar on August 07, 2019, 06:28:15 pm ---
--- Quote from: NaxFM on August 07, 2019, 02:44:57 pm --- You can't have a negative gain, the gain is always positive, less than one if it's an attenuation, more if it's a gain.
--- End quote ---
I don't think that's right. https://en.wikipedia.org/wiki/Decibel shows negative numbers. 0 dB is gain of unity. Negative gains get negative numbers in dB. WIFI ranges in the -60 dB range. Audio too.
--- End quote ---
Well, yes, speaking in terms of deciBels you can have negative gain. I didn't say that, but I was talking about gain expressed as a pure number.
If the ratio is less than one, then the gain in deciBels is negative
Inviato dal mio Moto G (5S) Plus utilizzando Tapatalk
radiolistener:
--- Quote from: soldar on August 07, 2019, 06:28:15 pm ---Negative gains get negative numbers in dB.
--- End quote ---
Negative gain in dB is not a gain, this is attenuation :)
soldar:
--- Quote from: radiolistener on August 09, 2019, 03:31:50 am --- Negative gain in dB is not a gain, this is attenuation :)
--- End quote ---
Attenuation is the same as "negative gain" and both are correct. Just like a negative profit is a loss, negative growth is shrinking, etc.
A program designed to calculate gain can output the result as "Gain: -20 dB" and it is not incorrect.
mikerj:
--- Quote from: soldar on August 09, 2019, 06:39:49 am ---
--- Quote from: radiolistener on August 09, 2019, 03:31:50 am --- Negative gain in dB is not a gain, this is attenuation :)
--- End quote ---
Attenuation is the same as "negative gain" and both are correct. Just like a negative profit is a loss, negative growth is shrinking, etc.
A program designed to calculate gain can output the result as "Gain: -20 dB" and it is not incorrect.
--- End quote ---
Exactly, the sign changes depending on whether you refer to a value as a gain or an attenuation.
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