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ｄ B or not dB

ｄ B or not dB. http://www.unav.es/adi/servlet/Web2?course=80957943&action=verWeb&pagina=21510. ｄ B or not dB. Ratio of two quantities. Large numerical ranges. Example Mobile radiobase station transmits approx. a power of 80W Mobile phone receives only about 0.000 000 002W = 2nW

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ｄ B or not dB

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  1. ｄB or not dB http://www.unav.es/adi/servlet/Web2?course=80957943&action=verWeb&pagina=21510

  2. ｄB or not dB • Ratio of two quantities. • Large numerical ranges. Example • Mobile radiobase station transmits approx. a power of 80W • Mobile phone receives only about 0.000 000 002W = 2nW • 2nW is a 0.000 000 002 5% of 80W • The base station in our example transmits at +49 dBm • The mobile phone receives -57 dBm • Power difference of +49 dBm - (-57 dBm) = 106 dB

  3. dB or not dB Example • If we cascade two amplifiers with power gains of 12 and 16, respectively, • The total gain is 12 times 16 = 192 (which you can hopefully calculate in your head easily – can you?). • In logarithmic terms, the two amplifiers have gains of 10.8 dB and 12 dB, respectively, producing a total gain of 22.8 dB, which is definitely easier to calculate.

  4. ｄB or not dB dB

  5. ｄB or not dB dBm Examples: The output power range of signal generators extends typically from -140 dBm to +20 dBm or 0.01 fW (femto Watt) to 0.1 W. Mobile radio base stations transmit at +43 dBm or 20 W. Mobile phones transmit at +10 dBm to +33 dBm or 10 mW to 2 W. Broadcast transmitters operate at +70 dBm to +90 dBm or 10 kW to 1 MW.

  6. ｄB or not dB dBc • We reference this power to the power of the carrier to produce a result in dBc (1 Hz bandwidth) @ a foffset. • The c in dBc stands for “carrier”.

  7. ｄB or not dB

  8. ｄB or not dB • Importance of speaking properly and therefore employing the right units for any parameter. http://youtube.com/watch?v=_tA0m8OPJB8

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