Chapter 3: Amplitude Modulation

AM stands for: a. Audio Modulation c. Angle Modulation b. Amplitude Modulation d. Antenna Modulation

B

"The ""envelope"" of an AM signal is due to: a. the baseband signal c. the amplitude signal b. the carrier signal d. none of the above"

A

If the audio Va sin(ωat) modulates the carrier Vc sin(ωc t), then the modulation index, m, is: a. m = ωa / ωc c. m = (Va / Vc) 2 b. m = Va / Vc d. m = Va / ω

B

The equation for full-carrier AM is: a. v(t) = (Ec + Em) × sin(ωc t) c. v(t) = (Ec × Em) × sin(ωmt) × sin(ωc t) b. v(t) = (Ec + Em) × sin(ωmt) + sin(ωc t) d. v(t) = (Ec + Em sin(ωmt)) × sin(ωc t)

D

Overmodulation causes: a. distortion c. both a and b b. splatter d. none of the above

C

The peak voltage of an AM signal goes from Emax to Emin. The modulation index, m, is: a. m = Emin / Emax c. m = (Emax - Emin) / (Emax + Emin) b. m = Emax / Emin d. m = (Emax + Emin) / (Emax - Emin)

C

If Va sin(ωat) amplitude modulates the carrier Vc sin(ωc t), it will produce the frequencies: a. ωc + ωa and ωc - ωa c. ωc + ωa and 2ωc + 2ωa b. (ωc + ωa)/2 and (ωc - ωa)/2 d. none of the above

A

At 100% modulation, the total sideband power is: a. equal to the carrier power c. half the carrier power b. twice the carrier power d. 1.414 × carrier power

C

If a 5-kHz signal modulates a 1-MHz carrier, the bandwidth of the AM signal will be: a. 5 kHz c. 1.005 MHz b. 10 kHz d. none of the above

B

If an AM radio station increases its modulation index, you would expect: a. the audio to get louder at the receiver c. the signal-to-noise ratio to increase b. the received RF signal to increase d. all of the above

D

The modulation index can be derived from: a. the time-domain signal c. both a and b b. the frequency-domain signal d. none of the above

C

The main problem in using quadrature AM would be: a. requires too much bandwidth c. incompatibility with ordinary AM radios b. requires too much power d. all of the above

C

As compared to plain AM, SSB AM: a. is more efficient b. requires a more complex demodulator circuit c. requires less bandwidth d. all of the above

D

The SC in SSB SC stands for: a. single-carrier c. sideband-carrier b. suppressed-carrier d. none of the above

B

PEP stands for: a. Peak Envelope Power c. Peak Envelope Product b. Peak Efficiency Power d. none of the above

A

If an SSB transmitter radiates 1000 watts at peak modulation, what will it radiate with no modulation? a. 1000 watts c. 250 watts b. 500 watts d. 0 watts

D

"Music on AM radio stations is ""low-fidelity"" because: a. AM is susceptible to noiseb. commercial AM stations use low power c. commercial AM stations have a narrow bandwidth d. all of the above"

C

. The type of information that can be sent using AM is: a. audio c. digital data b. video d. all of the above

D

. Two tones modulate an AM carrier. One tone causes a modulation index of m1 and the other tone causes a modulation index of m2. The total modulation index is: a. m1 + m2 c. sqrt(m1 × m2 + m2 × m1) b. (m1 + m2) / 2 d. sqrt(m1 × m1 + m2 × m2)

D

To demodulate a USB SSB signal, the receiver must: a. be set to USB mode c. both a and b b. reinsert the carrier d. none of the above

C