# Electronic Communications Systems Tomasi Chapter 7 And 8

47 Questions

Electronic communications systems subject

• 1.
Results whenever the phase angle of a sinusoidal wave is varied with respect to tiime
• 2.
Angle Modulation results whenever the _________ of a sinusoidal wave is varied with respect to time
• 3.
The two forms of angle modulation are ________ and ________
• 4.
_______ is varying the frequency of a constant amplitude carrier directly proportional to the amplitude of the modulating signal at a rate equal to the frequency of the modulating signal
• 5.
__________ is varying the phase of a constant amplitude carrier directly proportional to the amplitude of the modulation signal at a rate equal to the frequency of the modulating signal
• 6.
Direct frequency modulation is varying the frequency of a ______ amplitude carrier directly proportional to the amplitude of the modulating signal at a rate equal to the frequency of the modulating signal.
• 7.
Direct frequency modulation is varying the frequency of a constant amplitude carrier _____ ______ to the amplitude of the modulating signal at a rate equal to the frequency of tthe modulating signal.
• 8.
When _____ of a signal is varied, it's phase is also varied
• 9.
The ______ between frequency and phase modulation lies in which property of the carrier is directly varied by the modulating signal.
• 10.
The difference between frequency and phase modulation lies in which property of the carrier is ____ _____ by the modulating signal
• 11.
If the modulating signal ______ the frequency directly, frequency modulation results
• 12.
If the modulating signal varies the frequency directly, _____ ______ results
• 13.
If the modulating signal varies the phase directly, ___ ____ results.
• 14.
FM has the ability to ______ _____, which is probably the biggest advantage of FM compared to AM
• 15.
FM receivers can be fitted with _____ ______ to remove amplitude variations caused by noise, making FM more immune to noise.
• 16.
FM receivers can be fitted with amplitude limiters to remove amplitude variations caused by noise, making FM more immune to noise. This is called __ ________
• 17.
In __, once the signal has been contaminated by noise, noise cannot be removed
• 18.
_____ can be improved further by increasing the frequency deviation of FM signals
• 19.
Signal to noise ratio can be improved further by increasing the ______ of FM signals
• 20.
Reduced noise improves _____
• 21.
_____ improves system fidelity
• 22.
Angle modulated signals are more _________
• 23.
Amplitude of FM and PM remains _____
• 24.
Amplitude is _____ of modulation depth
• 25.
In angle modulation, _____ may be used, but all subsequent can be class C and therefore more power efficient
• 26.
In angle modulation, all transmitted power in FM are useful, making it more ______
• 27.
Standard frequency allocations provide ______ between FM broadcast stations, so there is less adjacent channel interference.
• 28.
Standard frequency allocations provide guard band between FM broadcast stations, so there is ____ adjacent channel interference
• 29.
There is ____ noise in MF and HF than in VHF and UHF
• 30.
For FM, the radius is limitted more than line of _____
• 31.
For FM broadcasts, ______ is used, so that the radius of operation is limitted slightly more than line of sight
• 32.
For FM broadcasts, several independent transmitters separated by space can use  the ____ frequency with less possible interference
• 33.
With FM and PM, a phenomenon known as _____ allows a receiver to differentiate between two signals with the same frequency
• 34.
In capture effect, the signals ratio, one of the signals is _____ as high as the other.
• 35.
In angle modulation, _____ bandwidth is needed compared to AM
• 36.
In angle modulation, there is ____ complex circuits than in AM
• 37.
In Angle modulation, since reception is limitted in line of sight, the area of reception is much _____ than AM.
• 38.
In PM, when the carrier signal is not modulated, its frequency is constant and is equal to the ________
• 39.
In PM, when the carrier signal is modulated by a modulating signal, its ________ will change depending on the instantaneous value of the modulating signal voltage.
• 40.
In PM, the higher is the modulating signal voltage the higher is the ______
• 41.
In PM, the higher is the peak amplitude of the modulating signal, the higher is the ____
• 42.
In PM, the peak phase deviation occurs when the _____ of the modulating signal is at its peak.
• 43.
In PM, while the phase of the carrier is changing, its frequency will also be changing. _____ FM will result
• 44.
____ indicates how much phase of the carrier is changing with respect to its reference phase.
• 45.
____ is the precise phase of the carrier at a given instant of time
• 46.
In FM, when the carrier signal is modulated by a modulating signal, its instantaneous frequency will change depending on the ______ of the modulating signal
• 47.
In FM, the higher is the modulating signal voltage, the higher is the _____
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