telecommunication Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that fe ...

, reference noise is the magnitude of circuit

noise Noise is unwanted sound considered unpleasant, loud or disruptive to hearing. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrations through a medium, such as air or water. The difference arise ...

chosen as a reference for measurement. Many different levels with a number of different weightings are in current use, and care must be taken to ensure that the proper parameters are stated. Specific ones include: dBa, dBa(F1A), dBa(HA1), dBa0,

dBm DBM or dbm may refer to: Science and technology * dBm, a unit for power measurement * DBM (computing), family of key-value database engines including dbm, ndbm, gdbm, and Berkeley DB * Database Manager (DBM), a component of 1987's ''Extended Edi ...

, dBm(psoph), dBm0,

dBrn The symbol dBrn or dB(rn) is an abbreviation for decibels above reference noise. Weighted noise power in dB is referred to 1.0 picowatt. Thus, 0 dBrn = -90 dBm. Use of 144 line, 144-receiver, or C-message weighting, or flat weighting, can be ...

dBrnC The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a p ...

, dBrnC0, dBrn(f₁-f₂), dBrn(144-line), dBx.

References

* Noise (electronics) Communication circuits Telecommunications techniques {{telecomm-stub