Synchronization of a time base at a local clock to a reference time. Initially, correction data (e.g., synchronization data) may be derived from packet data received over an asynchronous packet-switched network (e.g., the internet). Correction data derived from the packet data may be used to correct at least a portion of the time base (e.g., a frequency component). In turn, once the time base is corrected (e.g., to better than a predetermined quality threshold), the source of synchronization data may change to an alternate (e.g., more accurate source) such as positioning signals from a positioning system. In this regard, the corrected time base may be used to assist in acquiring such positioning signals to allow for higher accuracy correction. Furthermore, use of the positioning system may allow for correction of a phase of the time base (e.g., to align the phase to the positioning system. In turn, an accurate time base may be utilized (e.g., for location determination using the positioning system) and/or other contexts such as a downstream communication operation. For instance, a device employing the synchronization techniques described herein may be an LTE base station used to facilitate downstream communication with another device by use of the synchronized time base.