The term bandwidth in this context refers to which portion of the spectrum?

The term bandwidth in this context refers to which portion of the spectrum?

• A. A All frequencies including negative
• B. B Positive frequencies only
• C. C Zero frequency only
• D. D Frequencies above the Nyquist frequency

Answer: (B)

In signal processing, bandwidth is about the range of frequencies that actually carry signal energy. For real-valued time signals, the Fourier spectrum is symmetric around zero, so the negative frequencies don’t add new information—the same content appears mirrored on the positive side. That means the meaningful span of frequencies is from zero up to the highest positive frequency present. So the bandwidth is the extent of that positive part of the spectrum. For example, if a real signal has components up to 5 kHz, its bandwidth is 5 kHz. The negative side of the spectrum is just a mirror image, not an independent part of the bandwidth. Frequencies above the Nyquist frequency aren’t part of the signal’s bandwidth in typical baseband analysis; they’re either not representable at the given sampling rate or would be aliased. Likewise, zero frequency alone would indicate no variation (DC), not a usable bandwidth. Thus, the correct interpretation is that bandwidth refers to positive frequencies only.

In signal processing, bandwidth is about the range of frequencies that actually carry signal energy. For real-valued time signals, the Fourier spectrum is symmetric around zero, so the negative frequencies don’t add new information—the same content appears mirrored on the positive side. That means the meaningful span of frequencies is from zero up to the highest positive frequency present. So the bandwidth is the extent of that positive part of the spectrum.

For example, if a real signal has components up to 5 kHz, its bandwidth is 5 kHz. The negative side of the spectrum is just a mirror image, not an independent part of the bandwidth. Frequencies above the Nyquist frequency aren’t part of the signal’s bandwidth in typical baseband analysis; they’re either not representable at the given sampling rate or would be aliased. Likewise, zero frequency alone would indicate no variation (DC), not a usable bandwidth. Thus, the correct interpretation is that bandwidth refers to positive frequencies only.