Inside the Cable Modem: Modulator

In cable modems that use the cable system for upstream traffic, a modulator is used to convert the digital computer network data into radio-frequency signals for transmission. This component is sometimes called a burst modulator, because of the irregular nature of most traffic between a user and the Internet, and consists of three parts:

• A section to insert information used for error correction on the receiving end
• A QAM modulator
• A digital-to-analog (D/A) converter