What signals are used to conduct a two-tone test?
The correct answer is B: Two non-harmonically related audio signals. The signals used to conduct a two-tone test are two non-harmonically related audio signals. Two-tone tests use two audio tones that aren't harmonics of each other to test transmitter linearity. For amateur radio operators, this is a standard test for SSB transmitters. Understanding this helps when testing transmitter performance.
Exam Tip
Two-tone test = two non-harmonically related audio signals. Think 'T'wo-'T'one = 'T'wo 'T'ones 'N'on-harmonic. Uses two audio tones that aren't harmonics of each other to test transmitter linearity. Not same frequency, not swept, not square waves - just two non-harmonic tones.
Memory Aid
"Two-tone test = two non-harmonically related audio signals. Think 'T'wo-'T'one = 'T'wo 'T'ones 'N'on-harmonic. Uses two audio tones that aren't harmonics of each other to test transmitter linearity. Standard test for SSB transmitters."
Real-World Application
You conduct a two-tone test on your SSB transmitter. You inject two audio tones (e.g., 700 Hz and 1900 Hz - non-harmonically related) into the microphone input. The transmitter should produce only these two tones and their sum/difference products. Any other products indicate non-linearity. This tests transmitter linearity.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Two tones of the same frequency shifted 90 degrees aren't used - that's a single tone with phase shift, not a two-tone test. Two-tone tests need two different frequencies.
Option C: Incorrect. Two swept frequency tones aren't used - two-tone tests use fixed frequencies, not swept. Swept tones are for different tests.
Option D: Incorrect. Square wave signals aren't used - two-tone tests use sine waves, not square waves. Square waves have harmonics that would interfere with the test.
题目解析
The correct answer is B: Two non-harmonically related audio signals. The signals used to conduct a two-tone test are two non-harmonically related audio signals. Two-tone tests use two audio tones that aren't harmonics of each other to test transmitter linearity. For amateur radio operators, this is a standard test for SSB transmitters. Understanding this helps when testing transmitter performance.
考试技巧
Two-tone test = two non-harmonically related audio signals. Think 'T'wo-'T'one = 'T'wo 'T'ones 'N'on-harmonic. Uses two audio tones that aren't harmonics of each other to test transmitter linearity. Not same frequency, not swept, not square waves - just two non-harmonic tones.
记忆口诀
Two-tone test = two non-harmonically related audio signals. Think 'T'wo-'T'one = 'T'wo 'T'ones 'N'on-harmonic. Uses two audio tones that aren't harmonics of each other to test transmitter linearity. Standard test for SSB transmitters.
实际应用示例
You conduct a two-tone test on your SSB transmitter. You inject two audio tones (e.g., 700 Hz and 1900 Hz - non-harmonically related) into the microphone input. The transmitter should produce only these two tones and their sum/difference products. Any other products indicate non-linearity. This tests transmitter linearity.
错误选项分析
Option A: Incorrect. Two tones of the same frequency shifted 90 degrees aren't used - that's a single tone with phase shift, not a two-tone test. Two-tone tests need two different frequencies. Option C: Incorrect. Two swept frequency tones aren't used - two-tone tests use fixed frequencies, not swept. Swept tones are for different tests. Option D: Incorrect. Square wave signals aren't used - two-tone tests use sine waves, not square waves. Square waves have harmonics that would interfere with the test.
知识点
Two-tone test, Non-harmonically related, Audio signals, Transmitter testing
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.