Bandwidth is the width, in hertz, of the frequency range a signal occupies or that a receiver captures.¹ A narrowband voice channel may be ~12.5 kHz wide; an FM broadcast station ~200 kHz; Wi-Fi tens of megahertz.

Bandwidth is the span of frequency a signal occupies — wider signals carry more data but use more spectrum.

How it works

Wider bandwidth can carry more information but uses more spectrum and demands a higher sample rate to capture (per the Nyquist theorem). It also admits more noise, affecting SNR.

Relevance to SDR

An SDR’s capture bandwidth (≈ its sample rate) sets how much spectrum you see at once. Filtering and decimation narrow a wide capture down to a single channel’s bandwidth.

Sources

1. Bandwidth (signal processing) — Wikipedia, definition and measures of signal bandwidth. ↩

See also

• Sample rate
• Nyquist–Shannon sampling theorem
• Frequency
• Signal-to-noise ratio (SNR)

Learn it step by step

• Anatomy of a signal
• Sample rate, bandwidth & Nyquist