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dB(1 W) — same as dBm, with reference level of 1 watt. Electric voltage. dBu or dBv . dB(0.775 V) — (usually RMS) voltage amplitude referenced to 0.775 volt. Although dBu can be used with any impedance, dBu = dBm when the load is 600 Ω. dBu is preferable, since dBv is easily confused with dBV. The "u" comes from "unloaded". dBV ................
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