GROL Test Equipment and Measurements 1 — Questions and Answers
Question 1: What instrument is used to measure the standing wave ratio (SWR) on a transmission line?
- Spectrum analyzer
- Oscilloscope
- SWR meter (directional wattmeter) (Correct answer)
- Signal generator
Correct answer: SWR meter (directional wattmeter)
An SWR meter (or directional wattmeter) measures forward and reflected power on a transmission line to calculate the standing wave ratio.
Question 2: What does a spectrum analyzer display?
- Signal amplitude versus time
- Signal amplitude versus frequency (Correct answer)
- Phase versus frequency
- Impedance versus frequency
Correct answer: Signal amplitude versus frequency
A spectrum analyzer displays signal amplitude (usually in dBm) as a function of frequency, allowing visualization of harmonics, spurious signals, and bandwidth.
Question 3: What is the function of a signal generator in RF testing?
- To measure transmitted power
- To provide a known, calibrated test signal at a specified frequency and amplitude (Correct answer)
- To display waveform shape on a screen
- To measure noise figure
Correct answer: To provide a known, calibrated test signal at a specified frequency and amplitude
A signal generator produces a stable, calibrated output signal used to test and align receivers, filters, and other RF equipment.
Question 4: What does an oscilloscope primarily measure?
- Frequency spectrum of a signal
- Voltage as a function of time (Correct answer)
- Power in dBm
- SWR on a transmission line
Correct answer: Voltage as a function of time
An oscilloscope displays voltage waveforms as a function of time, allowing measurement of amplitude, frequency, period, and waveshape.
Question 5: What is a dummy load used for in radio testing?
- To increase transmitter power output
- To provide a non-radiating resistive load for testing transmitters without transmitting over the air (Correct answer)
- To match a mismatched antenna system
- To measure receiver sensitivity
Correct answer: To provide a non-radiating resistive load for testing transmitters without transmitting over the air
A dummy load is a non-inductive resistive load that absorbs transmitter power without radiating, allowing testing and adjustment without causing interference.
Question 6: What is the purpose of a frequency counter in radio equipment testing?
- To measure signal power in watts
- To accurately measure the frequency of an oscillator or transmitted signal (Correct answer)
- To display harmonic content
- To measure capacitance
Correct answer: To accurately measure the frequency of an oscillator or transmitted signal
A frequency counter counts the number of cycles of a signal per second to provide a precise digital readout of the operating frequency.
GROL Test Equipment and Measurements 1
What instrument is used to measure the standing wave ratio (SWR) on a transmission line?