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Confusion here, can someone clarify? If dB is used to compare, compare with what? E.g., dBm is decibel milliwatts (as we see in some of the specs of the Prism2Cards) is relative to what? Secondly, I thought I heard DrEngelson say that in dBi the "i" stood for electrical current, but the sound decibels were awfully low, so I could easily have that wrong. Maybe someone could check. -- RussellSenior |
The Bel is named after Alexander Graham Bell, and is the base 10 logarithm of the ratio of two power levels. Originally, the Bel was used to compare two audio power levels in terms of the response to them by the human ear because the human ear responds logarithmically to audio power levels.
In the wireless world DeciBels (or dB) are used as a convenient common until to convert wireless measurements to. Some measurements that you will see represented as dB are:
- dBm - decibel milliwatts
- dBi - decibel isotrops? (referring an Isotropic Antenna)
- dBw - decibel watts
Confusion here, can someone clarify? If dB is used to compare, compare with what? E.g., dBm is decibel milliwatts (as we see in some of the specs of the Prism2Cards) is relative to what?
Secondly, I thought I heard DrEngelson say that in dBi the "i" stood for electrical current, but the sound decibels were awfully low, so I could easily have that wrong. Maybe someone could check.