Frequency synchronizing a local oscillator in a remote unit in a distributed antenna system (DAS) used for frequency shifting communications signals based on a received digital pulse signal from a central unit. A remote unit receives a frequency shifted downlink communications signal and a reference pulse signal indicative of a frequency of a reference oscillator from a central unit. To recover the original signal, a mixing frequency signal generated by a local oscillator is used. To recover a signal having the same frequency as the original signal, the local oscillator should be the same or substantially the same frequency as the frequency used to create the frequency shifted version. A time difference signal indicating the frequency difference between the oscillators is calculated. A frequency adjustment signal is provided to the local oscillator based on the time difference signal to decrease the frequency difference between the oscillators.