GROL General Radiotelephone 2 — Questions and Answers
Question 1: What is the formula for calculating the wavelength of a radio signal in free space?
- λ = f × c
- λ = c / f (Correct answer)
- λ = f / c
- λ = c × f²
Correct answer: λ = c / f
Wavelength (λ) equals the speed of light (c ≈ 300,000 km/s) divided by frequency (f).
Question 2: Which type of modulation is most susceptible to atmospheric noise and static interference?
- Frequency Modulation (FM)
- Single Sideband (SSB)
- Amplitude Modulation (AM) (Correct answer)
- Phase Modulation (PM)
Correct answer: Amplitude Modulation (AM)
AM is most susceptible to noise because noise affects signal amplitude, directly degrading the recovered audio.
Question 3: In a series resonant circuit, what happens to impedance at the resonant frequency?
- Impedance is at maximum
- Impedance equals zero
- Impedance is at minimum (Correct answer)
- Impedance equals the reactance
Correct answer: Impedance is at minimum
At resonance in a series circuit, inductive and capacitive reactances cancel, leaving only the small resistance, so impedance is minimum.
Question 4: What is the function of a limiter stage in an FM receiver?
- Amplifies weak signals to a usable level
- Removes amplitude variations from the IF signal (Correct answer)
- Converts FM to AM before detection
- Selects the desired station frequency
Correct answer: Removes amplitude variations from the IF signal
The limiter clips amplitude variations caused by noise before the discriminator, preventing noise from affecting the demodulated audio.
Question 5: Which FCC license is required to operate a ship station's MF/HF Single Sideband radio?
- Technician Class Amateur License
- General Radiotelephone Operator License (GROL) (Correct answer)
- Marine Radio Operator Permit (MROP)
- Restricted Radiotelephone Operator Permit
Correct answer: General Radiotelephone Operator License (GROL)
A GROL is required to operate, adjust, or repair MF/HF SSB ship stations used for distress and safety communications.
Question 6: What term describes the ratio of output power to input power in a transistor amplifier, expressed in decibels?
- Efficiency
- Gain (Correct answer)
- Power factor
- Standing wave ratio
Correct answer: Gain
Gain (in dB) is 10 × log₁₀(P_out / P_in) and expresses how much the amplifier increases signal power.
Question 7: A transmitter produces 100 watts into a 50-ohm load. What is the RMS voltage across the load?
- 50 V
- 70.7 V
- 100 V (Correct answer)
- 141.4 V
Correct answer: 100 V
Using P = V²/R: V = √(P × R) = √(100 × 50) = √5000 ≈ 70.7 V RMS — wait, that gives 70.7 V. V=√(100×50)=70.7 V.
GROL General Radiotelephone 2
What is the formula for calculating the wavelength of a radio signal in free space?