A method and apparatus for determining time-of-day in a mobile receiver is described. In one example, expected pseudoranges to a plurality of satellites are obtained. The expected pseudoranges are based on an initial position of the mobile receiver and an initial time-of-day. Expected line-of-sight data to said plurality of satellites is also obtained. Pseudoranges from said mobile receiver to said plurality of satellites are measured. Update data for the initial time-of-day is computed using a mathematical model relating the pseudoranges, the expected pseudoranges, and the expected line-of-sight data. The expected pseudoranges and the expected line-of-sight data may be obtained from acquisition assistance data transmitted to the mobile receiver by a server. Alternatively, the expected pseudoranges may be obtained from acquisition assistance data, and the expected line-of-sight data may be computed by the mobile receiver using stored satellite trajectory data, such as almanac data.