Time-Stable Receiving System With Local Digitization Based on a Dithered Sample Clock

We present a time-stable receiving system for broadband signals transmitted via a 25 km fiber optic link. The timing jitter of the signal induced by the transmission link is precisely eliminated after the signal is digitized with a dithered sample clock. The dithered clock is generated from the phase of a voltage-controlled oscillator, introducing the same transmission timing jitter of the link. Therefore, it can withstand an unlimited range of transmission delay variations without using any optical or electrical delay lines. Experimentally, binary phase-shift keying signals with bandwidths of several hundred MHz and different carrier frequencies are transmitted and received by the proposed system. The root mean square of the calculated timing jitters of the received signals is decreased to the order of picosecond. The simple remote end and immunity to environmental perturbations of the proposed scheme make it an ideal candidate for a large-scale distributed antenna system.