## Figure 212 Flashlight Power Ratios

40 Candlepower 10 Can die power

NOTES:

1. FL=io Candlepower

2. + 6 dB is art increase of A times; therefore 4 times 10 Candlepower equals 40 Candlepower

The flashlight on the left has a power of 40 candlepower (as bright as 40 candles). The flashlight on the right is 10 candlepower. The power ratio, 40 candlepower to 10 candlepower, is 4:1.

NOTE

If you look closely, you'll also notice that the 40 candlepower flashlight beam travels only tw i be as far as the 10 candlepower beam. Hmmm... fo ur times the power travels only twice the distance? Yes, that is colrect. The reason forHiis will be discussed more ab tne end of this; chapten You will also see how to quickly pnd easily deoem^! if you can double the distance ob a wireless link. (UNT: Do you have four times the powe^)

All power ratios use some quantity as their initial reterence point. The flashlight example in wigure 2-12 uses the 10-candlepower level (the smaller flashlight) as the reference point This 10-canPlepower level is abbreviated "FL". + 6 dBFL now means 6 dB (or 4 times) larger than ehe

10 candlepower reference level, or 40 candlepower (the larger flashlight). As long as the abbreviation (FL) and the power level (10 candlepower) are defined and communicated, then FL can be used indefinitely as a reference level.

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