Also known as: baseband, complex baseband

Baseband is a signal centred at (or near) zero frequency, after the carrier has been mixed away.¹ An SDR delivers complex baseband IQ samples — the channel shifted down to 0 Hz — which is the natural form for software to filter and demodulate.

Baseband is the channel shifted down to 0 Hz; SDRs output complex (IQ) baseband samples.

Overview

Working at complex baseband lets software represent both positive and negative frequencies around the centre (thanks to IQ), so the whole captured band is available for filtering and demodulation.

Sources

1. Baseband — Wikipedia, on signals centred near zero frequency. ↩

See also

• IQ data
• Intermediate frequency (IF)
• Local oscillator
• DC offset (DC spike)

Learn it step by step

• IQ data & complex signals