Question
What describes orthogonal frequency-division multiplexing (OFDM)?
Answer Options
- A) A frequency modulation technique that uses non-harmonically related frequencies
- B) A bandwidth compression technique using Fourier transforms
- C) A digital mode for narrow-band, slow-speed transmissions
- D) A digital modulation technique using subcarriers at frequencies chosen to avoid intersymbol interference
Correct Answer: D
Explanation
Orthogonal Frequency-Division Multiplexing (\text{OFDM}) is a sophisticated digital modulation technique that splits a high-speed digital stream into many slower data streams. Each stream is modulated onto its own \text{RF} carrier, called a subcarrier, which are all transmitted simultaneously on a single channel.
\text{OFDM} is precisely described as a digital modulation technique using subcarriers at frequencies chosen to avoid intersymbol interference. These subcarriers are mathematically positioned so that they do not interfere with the data carried by adjacent subcarriers. This structure makes \text{OFDM} highly resistant to multipath fading and very effective for transmitting large amounts of data reliably.
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