CHAPTER 4: ANGLE MODULATION

The FM modulation index: a. increases with both deviation and modulation frequency b. increases with deviation and decreases with modulation frequency c. decreases with deviation and increases with modulation frequency d. is equal to twice the deviation

B

One way to derive FM from PM is: a. integrate the modulating signal before applying to the PM oscillator b. integrate the signal out of the PM oscillator c. differentiate the modulating signal before applying to the PM oscillator d. differentiate the signal out of the PM oscillator

A

The bandwidth of an FM signal is considered to be limited because: a. there can only be a finite number of sidebands b. it is equal to the frequency deviation c. it is band-limited at the receiver d. the power in the outer sidebands is negligible

D

Mathematically, the calculation of FM bandwidth requires the use of: a. ordinary trigonometry and algebra c. Taylor series b. Bessel functions d. fractals

B

FM bandwidth can be approximated by: a. Armstrong's Rule c. Carson's Rule b. Bessel's Rule d. none of the above

C

NBFM stands for: a. National Broadcast FM c. Near Band FM b. Non-Broadcast FM d. Narrowband FM

D

When FM reception deteriorates abruptly due to noise, it is called: a. the capture effect c. the noise effect b. the threshold effect d. the limit effect

B

"An FM receiver switching suddenly between two stations on nearby frequencies is called: a. the capture effect c. the ""two-station"" effect b. the threshold effect d. none of the above"

A

Pre-emphasis is used to: a. increase the signal to noise ratio for higher audio frequencies b. increase the signal to noise ratio for lower audio frequencies c. increase the signal to noise ratio for all audio frequencies d. allow stereo audio to be carried by FM stations

A

"A pre-emphasis of 75 µs refers to: a. the time it takes for the circuit to work b. the ""dead time"" before de-emphasis occurs c. the time delay between the L and R channels d. the time-constant of the filter circuits used"

D

FM stereo: a. uses DSBSC AM modulation c. has a higher S/N than mono FM b. is implemented using an SCA signal d. is not compatible with mono FM

A

An SCA signal: a. can use amplitude modulation c. is monaural b. can use FM modulation d. all of the above

D

The modulation index of an FM signal can be determined readily: a. using measurements at points where J0 equals one b. using measurements at points where J0 equals zero c. using measurements at points where the deviation equals zero d. only by using Bessel functions

B