Question
What sound is heard from an audio device experiencing RF interference from a single sideband phone transmitter?
Answer Options
- A) A steady hum whenever the transmitter is on the air
- B) On-and-off humming or clicking
- C) Distorted speech
- D) Clearly audible speech
Correct Answer: C
Explanation
RF Interference (RFI) occurs when the transmitted radio frequency energy from an amateur station is picked up by a nearby electronic device and is unintentionally converted back into audible sound. When the source is a Single Sideband (SSB) phone transmitter, the device’s internal semiconductor junctions (e.g., a transistor’s base-emitter junction) act as unintended detectors.
Since SSB is suppressed-carrier amplitude modulation, the RFI is detected without the proper re-inserted carrier, resulting in distorted speech (sometimes described as ‘monkey chatter’ or high-pitched garble) being heard over the audio device’s speaker. If the speech were clearly audible, it would suggest the interference source was an Amplitude Modulation (AM) transmitter.
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