Also known as: analog-to-digital converter, ADC

An analog-to-digital converter (ADC) measures a continuous signal many times per second, turning it into a stream of numbers.¹ In an SDR it produces the IQ samples software works on.

The ADC measures the signal at a fixed rate, converting the continuous waveform into digital samples.

How it works

Its sample rate sets how much bandwidth can be captured (per the Nyquist theorem), and its range defines full scale — exceed it and the signal clips at 0 dBFS.

Relevance to SDR

Setting gain so strong signals stay below the ADC’s ceiling, without burying weak ones in noise, is central to clean reception.

Sources

1. Analog-to-digital converter — Wikipedia, on sampling a continuous signal into discrete digital values. ↩

See also

• Sample rate
• Nyquist–Shannon sampling theorem
• dBFS
• Automatic gain control (AGC)
• Software-defined radio (SDR)

Learn it step by step

• How an SDR receiver works