Chapter 3: Amplitude Modulation- BLAKE

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