GROL Receivers and Transmitters 2

Question 1

What is the primary purpose of the IF (intermediate frequency) stage in a superheterodyne receiver?

Accepted Answer

To provide fixed-frequency amplification and selectivity

Answer

The IF stage amplifies and filters the signal at a fixed frequency after mixing, making high-quality filtering practical regardless of the tuned frequency.

Question 2

In a superheterodyne receiver, the local oscillator frequency is typically offset from the incoming RF signal by:

Accepted Answer

The intermediate frequency (IF)

Answer

Mixing the RF signal with the local oscillator (offset by the IF) produces a difference frequency equal to the IF, which is then amplified and filtered.

Question 3

What is the image frequency in a superheterodyne receiver?

Accepted Answer

A second RF frequency separated from the desired signal by twice the IF that also produces an IF output when mixed

Answer

The image frequency is separated from the desired signal by 2 × IF; it mixes with the local oscillator to produce an output at the IF just like the desired signal.

Question 4

Automatic Gain Control (AGC) in a receiver is designed to:

Accepted Answer

Maintain a relatively constant audio output level across a wide range of signal strengths

Answer

AGC reduces the gain of RF and IF amplifier stages when strong signals are received, preventing overloading while keeping weak signals audible.

Question 5

The noise figure of a receiver is a measure of:

Accepted Answer

How much noise the receiver itself adds relative to the thermal noise floor

Answer

Noise figure (in dB) quantifies the degradation of signal-to-noise ratio as the signal passes through the receiver; a lower number means less added noise.

(GROL) General Radiotelephone Operator License Practice Test

(GROL) General Radiotelephone Operator License Practice Test

GROL Receivers and Transmitters 2