WorksheetsPrinCom Quiz3
Total questions: 16
Worksheet time: 43mins
The FM modulation index:
increases with both deviation and modulation frequency
increases with deviation and decreases with modulation frequency
decreases with deviation and increases with modulation frequency
is equal to twice the deviation
The bandwidth of an FM signal is considered to be limited because:
there can only be a finite number of sidebands
it is equal to the frequency deviation
it is band-limited at the receiver
the power in the outer sidebands is negligible
FM bandwidth can be approximated by:
Armstrong's Rule
Bessel's Rule
Carson's Rule
none of the above
Pre-emphasis is used to:
increase the signal to noise ratio for higher audio frequencies
increase the signal to noise ratio for lower audio frequencies
increase the signal to noise ratio for all audio frequencies
allow stereo audio to be carried by FM stations
One way to derive FM from PM is:
integrate the modulating signal before applying to the PM oscillator
integrate the signal out of the PM oscillator
differentiate the modulating signal before applying to the PM oscillator
differentiate the signal out of the PM oscillator
FM and PM are two forms of (a) modulation.
Compared to AM, the signal-to-noise ratio of FM is usually (a) .
PM is extensively used in (a) communication.
Compared to AM, the bandwidth of FM is usually (a) .
In FM, as the modulating frequency decreases, the modulation index (a) .
An FM modulator has kƒ = 30 kHz/V and operates at a carrier frequency of 175 MHz. Find the output frequency for an instantaneous value of the modulating signal equal to:
(a) 150 mV (b) -2V
(a)
An transmitter generates an LSB signal with a carrier frequency of 8 MHz. What frequency will appear at the output with a two tone modulating signal with frequencies of 2 kHz and 3.5 kHz?
(a)
The same Fm modulator as in the previous example is modulated by a 3V sine wave. Calculate the deviation.
(a)
A transmitter has a carrier power of 10 W at an efficiency of 70 %. How much power must be supplied by the modulating amplifier for 100 % modulation?
(a)
A receiver has a sensitivity of 0.5 µV and a blocking dynamic range of 70 dB. What is the strongest signal that can be present along with a 0.5 µV signal without blocking taking place?
(a)
An FM detector produces a peak – to – peak output voltage of 1.2 V from an fm signal that is modulated to 10 kHz deviation by sine wave. What is the detector sensitivity?
(a)
