| Electronics > Beginners |
| converting Volt into dB |
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| 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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