The noise power, usually relative to a reference. Note: Noise level is usually measured in dB for relative power or picowatts for absolute power. A suffix is added to denote a particular reference base or specific qualities of the measurement. Examples of noise-level measurement units are dBa, dBa (F1A,) dBa (HA1,) dBa0, dBm, dBm (psoph,) dBm0, dBm0P, dBrn, dBrnC, dBrn (f1-f2,) dBrn (144-line,) pW, pWp, and pWp0.