Rescan

Rescan is the process of scanning again to locate items that were not found or to refresh a previously detected list. The term is used in broadcasting, electronics, and computing to describe rechecking channels, frequencies, devices, or media files.

In digital television receivers and set‑top boxes, a rescan re-detects available channels by scanning the service environment again. A full rescan rebuilds the channel lineup from scratch, while a partial or network-based rescan may update only changes in the lineup. Rescans are commonly performed after moving to a new location, changing service providers, or when the channel lineup has been updated.

In scanner radios and similar receivers, a rescan re-checks the programmed frequency list for activity. It may start from a saved point or continue through the memory to identify newly active frequencies or changes in existing ones, helping users maintain an up-to-date scan plan.

In computing and software contexts, rescanning often means re-detecting hardware or resources. For example, after connecting or disconnecting devices, a system may rescan to recognize new hardware. Media library programs may rescan the file system to find added or removed files, updating catalogs without requiring a full reinstall.

The exact behavior of a rescan depends on the device or application, and results can vary from preserving user settings to refreshing lists entirely.