Download modulation5 - WordPress.com

Continue Part V of the Series
201. What is emission F3F?
A. AM
B. Facsimile
C. Television
D. RTTY
202. What type of emission is produced when a frequency modulated transmitter is
modulated by a facsimile signal?
A. F3C
B. A3C
C. F3F
D. A3F
203. Two AM transmitting antennas are close together. As a result the two modulated
signals are mixed in the final RF stage of both transmitters. What is the resultant effect on
other station?
A. Harmonic interference
B. Intermodulation interference
C. Spurious interference
D. Crossmodulation interference
204. The term used to refer to the reduction of receiver gain caused by the signal of a
nearby station transmitter in the same frequency band?
A. Quieting
B. Cross-modulation interference
C. Squelch gain rollback
D. Desensitizing
205. What is the bandwidth occupied by the carrier, both sidebands and harmonics?
A. Authorized bandwidth
B. Bandwidth of emission and occupied bandwidth
C. Operating bandwidth
D. All of these
206. A class-C RF amplifier is collector amplitude modulated and its average dc level
collector current does not change. This means
A. A normal condition
B. Excessive drive to the base
C. Insufficient drive to the base
D. Insufficient audio modulation
207. What determines the percentage modulation of an FM transmitter?
A. Amplitude of the carrier
B. Modulating frequency
C. Carrier frequency
D. Amplitude of the modulating signal
208. Deviation ratio of an FM transmitter is the ratio of the
A. Maximum frequency swing to the highest modulating frequency
B. Operating frequency of the assigned frequency
C. Frequency swing to the modulating frequency
D. Highest modulating frequency to the minimum frequency
209. The main purpose of the beat frequency oscillator (BFO) is to generate
A. A 1 kHz not for Morse reception
B. Aid in the reception of weak voice-modulated signals
C. An output, whose frequency differs from the IF by 1 kHz
D. A signal, whose frequency is the same as intermediate frequency
210. Normally, a linear class BRF power amplifier operates with a bias approximately
equal to
A. Twice cut-off
B. Ten times cut-off value
C. 50% of cut-off value
D. Projected cut-off
211. The purpose why an RF amplifier is operated under linear class-B conditions (as
opposed to class-C) is to
A. Generate only even harmonics
B. Generate only odd harmonics
C. Increase the efficiency
D. Amplify of an AM signal
212. The term used to refer to the condition where the signal from a very strong station are
superimposed on other signal being received.
A. Cross-modulation interference
B. Intermodulation distortion
C. Receiver quieting
D. Capture effect
213. _________ is the amplitude of the maximum negative excursion of a signal as
viewed on an oscilloscope.
A. Peak-to-peak voltage
B. Inverse peak positive voltage
C. RMS voltage
D. Peak negative voltage
214. The type of emission that suffer most from selective fading.
A. CW and SSB
B. SSB and TV
C. FM and double sideband AM
D. SSTV and CW
215. In an FM-phone signal, ________ is the ratio between the actual frequency deviation
to the maximum frequency deviation.
A. FM compressibility
B. Modulating index
C. Percentage of modulation
D. Quieting index
216. _______ is used to refer to the reception blockage of one FM-phone signal by
another FM-phone signal.
A. Capture effect
B. Desensitization
C. Cross-modulation interference
D. Frequency discrimination
217. A receiver selectivity of 10 kHz in the IF circuitry is optimum for what type of signals?
A. SSB voice
B. Facsimile
C. FM
D. Double-sideband AM
218. If the envelope of modulation is constant in amplitude this means
A. Zero beat
B. Under-modulation
C. Zero-modulation
D. Over-modulation
219. What is the approximate bandwidth of an FM with a modulation factor of 12.5 and a
modulating frequency of 10 kHz?
A. 20 kHz
B. 270 kHz
C. 250 kHz
D. 45 kHz
220. Amplitude modulation is the same as
A. Linear mixing
B. Analog multiplication
C. Signal summation
D. Multiplexing
221. The negative half of the AM wave is supplied by a/an _______ on a diode modulator.
A.
B. Transformer
C. Capacitor
D. Inductor
222. One of the following can produce AM.
A. Having the carrier vary a resistance
B. Having the modulating signal vary a capacitance
C. Varying the carrier frequency
D. Varying the gain of an amplifier
223. Amplitude modulators that vary the carrier amplitude with the modulating signal by
passing it through an attenuator network is the principle of
A. Rectification
B. Amplification
C. Variable resistance
D. Absorption
224. Which component is used to produce AM at very high frequencies?
A. Varactor diode
B. Thermistor
C. Cavity resonator
D. PIN diode
225. A collector modulator has a supply voltage of 48 V. What is the peak-to-peak
amplitude of the modulating signal for 100 percent modulation?
A. 24 V
B. 48 V
C. 96 V
D. 120 V
226. What circuit recovers the original modulating information from an AM signal?
A. Modulator
B. Demodulator
C. Mixer
D. Crystal set
227. What is the most commonly used amplitude demodulator?
A. Envelope detector
B. Balanced modulator
C. Mixer
D. Crystal set
228. What circuit generates the upper and lower sidebands and suppresses the carrier?
A. Amplitude modulator
B. Diode detector
C. Class C amplifier
D. Balanced modulator
229. _________ is a widely used balanced modulator.
A. Diode bridge circuit
B. Full-wave bridge rectifier
C. Lattice modulator
D. Balanced bridge modulator
230. In a diode ring modulator, the diodes act like
A. Variable resistors
B. Switches
C. Rectifiers
D. Variable capacitors
231. The output of a balanced modulator is
A. AM
B. FM
C. SSB
D. DSB
232. The principal circuit in the popular 1496/1596 IC balanced modulator is a
A. Differential amplifier
B. Rectifier
C. Bridge
D. Constant current source
233. The most commonly used filter in SSB generators uses
A. LC networks
B. Mechanical resonators
C. Crystals
D. RC networks and op amps
234. In the phasing method of SSB generation, one sideband is canceled out due to
A. Phase shifting
B. Sharp selectivity
C. Carrier suppression
D. Phase inversion
235. A balanced modulator used to demodulate a SSB signal is call a/an
A. Transponder
B. Product detector
C. Converter
D. Remodulator
236. Frequency translation is done with a circuit called a
A. Summer
B. Multiplier
C. Divider
D. Mixer
237. Mixing for frequency conversion is the same as
A. Rectification
B. AM
C. Linear summing
D. Filtering
238. Which of the following is not a major advantage of FM over AM?
A. Greater efficiency
B. Noise immunity
C. Capture effect
D. Lower complexity and cost
239. The primary disadvantage of FM is its
A. Higher cost and complexity
B. Excessive use of spectrum space
C. Noise susceptibility
D. Lower efficiency
240. Noise is primarily
A. High-frequency spikes
B. Lowe-frequency variations
C. Random level shifts
D. Random frequency variations
241. The receiver circuit that rids FM of noise is the
A. Modulator
B. Demodulator
C. Limiter
D. Low-pass filter
242. The AM signals generated at a low level may only be amplified by what type of
amplifier?
A. Class A
B. Class B
C. Class C
D. All of the above
243. SSB means
A. Single sideband with suppressed carrier
B. Single sideband with carrier
C. Double sideband with no carrier
D. Single sideband with reduced carrier
244. A circuit used to select the desired output from a mixer
A. Transformer
B. Resonant circuit
C. Filter
D. Phase-shift circuit
245. What is the output of a balanced modulator?
A. AM
B. DSB
C. SSB
D. ISB
246. The acronym SSSC refer to
A. Suppressed sideband, single carrier
B. Suppressed sideband, suppressed carrier
C. Single sideband, suppressed carrier
D. Single sideband, single carrier
247. Which process occurs in the receiver?
A. Demodulation
B. Reception
C. Modulation
D. Recreation
248. What is usually used to demodulate SSB or CW signal?
A. PLL
B. BFO
C. Ratio detector
D. All of these OLDER POST
249. Which of the following is the most widely used amplitude modulator
A. Diode detector
B. PLL circuit
C. VCO
D. All of these
250. Which of the following is the most widely used balanced modulator
A. Full-wave bridge circuit
B. Balanced bridge modulator
C. Lattice modulator
D. None of these