Tone transmission communicates measurements by using what?

• A. A pure audible tone whose duration represents a measured value.
• B. A digital packet containing time-stamped data.
• C. A radio frequency carrier with amplitude encoding the value.
• D. A continuous stream of binary bits conveying the measurement.

Answer: (A)

Tone transmission conveys the measured value through the duration of a pure audible tone. The longer the tone lasts, the larger the represented value, so the receiver interprets the measurement by timing how long the tone is present. This is a simple, time-based encoding where the magnitude is encoded in length, not in amplitude, frequency, or discrete data packets. In contrast, digital packets would carry data as separate bytes, a RF carrier would encode value via amplitude or other modulation, and a continuous stream of binary bits is a digital signal rather than a single tone whose duration carries the value.