Question
What is the definition of symbol rate in a digital transmission?
Answer Options
- A) The number of control characters in a message packet
- B) The maximum rate at which the forward error correction code can make corrections
- C) The rate at which the waveform changes to convey information
- D) The number of characters carried per second by the station-to-station link
Correct Answer: C
Explanation
In a digital transmission, two key rates are used: the bit rate (bits per second) and the symbol rate (symbols per second). A symbol is a distinct change in the electrical or \text{RF} waveform (e.g., a change in frequency, phase, or amplitude) used to encode the digital data.
Therefore, the symbol rate is formally defined as the rate at which the waveform changes to convey information. The unit of symbol rate is the Baud (symbols per second). In simple modes like \text{CW} or RTTY, the symbol rate equals the bit rate. However, in complex modes like \text{QAM} or \text{QPSK}, one symbol may encode multiple bits, making the bit rate much higher than the symbol rate.
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