Active DAS

An active DAS converts the analog radio frequency transmissions from the signal source to a digital signal for distribution. A master unit performs this analog-to- digital conversion. The master unit may digitize the signal from a single carrier or multiple carriers. Once converted, the DAS transmits the digital signal over fiber optic or Ethernet cables to remote radio units (RRUs) that convert the signal back to an analog signal.

Unlike passive ( use RF passive components, such as rf directional coupler. power divider for DAS) or hybrid systems, active systems do not use coaxial cable to distribute signal. Fiber optic or Ethernet cable runs straight to the antenna unit and the conversion back to analog RF is done by circuitry inside the antenna.

ADVANTAGES

Ethernet or fiber optic cable can be shared with WiFi or public safety infrastructure (often complex in reality)

Easily expandable

No limits to lengths of cable runs

DISADVANTAGES

Considerably more expensive than passive or hybrid systems

Remote units are more expensive and require dedicated power