Analog-to-Digital Converters in Software-Defined Radio (SDR)

An Analog-to-Digital converter (ADC) is a device that converts an Analog signal to its Digital equivalent. The ADC is the bridge between the analog and digital in the world of SDR. It is in fact a key component of SDR.

The output of an ADC is a string of ones and zeros that vary with the incoming signal. This string can be processed by a Field Programmable Gate Array (FPGA) or a microprocessor.

Here are two examples of processing that can occur in the FPGA:

1. A Fast Fourier Transform (FFT) to convert the time domain signal to its frequency domain equivalent.
2. Digital filtering and demodulation to extract the content in the analog waveform.

The simplest way to get hands-on with an ADC is to get yourself an Arduino. The Arduino has a total of six analog input header pins that connect to its ADC.

Here are a couple of resources to get you started with understanding how to use the ADC in an Arduino.

Arduino – Simple ADC Youtube Tutorial

Sparkfun Blog Post on ADC