Practical implementation of a high-speed multichannel correlator with fiber-optic delays

We discuss architecture, subsystems, and applications of a multichannel digital correlator we constructed by using a combination of optical and electrical delays. Our system is capable of a 1-ns bin width in normal operation, when a derandomizer is used at the input stage and a 0.25-ns bin width when the derandomizer is bypassed. When switchable delay lines are used, the 16 real-time channels can access a 160-ns delay range, providing up to 160 channels at 1-ns bin width or 640 channels at 0.25-ns bin width.