Name:    dB Measurements

True/False
Indicate whether the statement is true or false.

1.

If the measured power is smaller than the reference power, the dB calculated will be a positive number and indicate a measurement of loss.

2.

If the measured power is larger than the reference power, the dB calculated will be a positive number and indicate a measurement of gain.

3.

International standards and some US standards that have adopted them calculate loss or attenuation as a positive number and gain as negative number, different from other definitions of dB.

Multiple Choice
Identify the choice that best completes the statement or answers the question.

4.

The “dB” or “decibel” was named for _________.
 a. The Liberty Bell b. Alexander Graham Bell c. Belle Star d. The Bell Curve

5.

In the equation defining dB, power is measured in units of ________.
 a. Watts, milliwatts or microwatts b. dB c. dBm d. Newtons

6.

If the dB equation is used for defining dBm, ________.
 a. The measured power must be in milliwatts b. The reference power is 1 milliwatt c. The reference power can be any power from +20 to -30 dBm d. Both measurements must be in dB

7.

If the measured power is twice the reference power, the dB equation will calculate the dB change as , ________.
 a. -3dB b. -2 dB c. 0 dB d. +3dB

8.

If the measured power is equal to the reference power, the dB equation will calculate the dB  as , ________.
 a. -3dB b. -2 dB c. 0 dB d. +3dB

9.

If the measured power is half the reference power, the dB equation will calculate the dB change as , ________.
 a. -3dB b. -2 dB c. 0 dB d. +3dB

10.

The difference between dB and dBm is ___________.
 a. dB measures power while dBm measures gain or loss b. dBm measures power while dB measures gain or loss

11.

If you are measuring the output of a fiber optic transmitter, you make the measurement in _________.
 a. dB b. dBm

12.

If you are measuring the input of a fiber optic receiver, you make the measurement in _________.
 a. dB b. dBm

13.

If you are measuring the loss of a fiber optic cable, you make the measurement in _________.
 a. dB b. dBm

14.

OTDRs and OLTS measure loss as a positive number and gain as a negative number because ____________.
 a. Both mresure the loss first then the reference b. They follow an international standard that changed the dB equation c. Both measure using backscatter which changes the ratio of power d. Their display cannot show negative numbers