The spectrum repack reduces the frequences which are used for over-the-air television so they can be used for other services such as 5G wireless. As a result many stations will begin transmitting on a different frequency. In some cases they may also transmit from a new location. This is a nationwide change that is being conducted in phases – The San Francisco – Oakland – San Jose area is in Phase 9, with a few stations in Phase 8.
As described below, SF Bay Area viewers are already being affected by the work required to prepare for the repack.