A-006-03: RF, IF amplifiers, selectivity
What is meant by the noise floor of a receiver?
The weakest signal that can be detected above the receiver internal noise
The weakest signal that can be detected under noisy atmospheric conditions
The minimum level of noise that will overload the receiver RF amplifier stage
The amount of noise generated by the receiver local oscillator
Which of the following is a purpose of the first IF amplifier stage in a receiver?
To improve selectivity
To tune out cross-modulation distortion
To increase dynamic response
To improve noise figure performance
How much gain should be used in the RF amplifier stage of a receiver?
Sufficient gain to allow weak signals to overcome noise generated in the first mixer stage
As much gain as possible, short of self-oscillation
It depends on the amplification factor of the first IF stage
Sufficient gain to keep weak signals below the noise of the first mixer stage
What is the primary purpose of an RF amplifier in a receiver?
To improve the receiver noise figure
To vary the receiver image rejection by using the AGC
To develop the AGC voltage
To provide most of the receiver gain
What is the primary source of noise that can be heard in a VHF/UHF band receiver with its antenna connected?
Receiver front-end noise
What is the term used for the decibel difference (or ratio) between the largest tolerable receiver input signal (without causing audible distortion products) and the minimum discernible signal (sensitivity)?
The lower the receiver noise figure becomes, the greater will be the receiver's _________ :
rejection of unwanted signals
The noise generated in a receiver of good design originates in the:
RF amplifier and mixer
detector and AF amplifier
BFO and detector
IF amplifier and detector
Why are very low noise figures relatively unimportant for a high frequency receiver?
external HF noise, man-made and natural, are higher than the internal noise generated by the receiver
ionospheric distortion of the received signal creates high noise levels
the use of SSB and CW on the HF bands overcomes the noise
regardless of the front end, the succeeding stages when used on HF are very noisy
The term which relates specifically to the amplitude levels of multiple signals that can be accommodated during reception is called:
Normally, front-end selectivity is provided by the resonant networks both before and after the RF stage in a superheterodyne receiver. This whole section of the receiver is often referred to as the:
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