Phase-Noise Cancellation Design for a 2000 Kilometre Optical Fibre Frequency Link

Phase-noise cancellation on a fibre link is limited by light travel time: a correction cannot respond faster than the round trip allows. Segmenting a long link into repeater spans raises the cancellation bandwidth of each span and is the standard architectural answer. This design paper computes delay and cancellation bandwidth for four lengths, sizes a two-thousand-kilometre link as eight spans, and states the residual performance the architecture is intended to protect. The computed results, taken from the deposited script, are as follows in summary: The computed rows entry 1 length_km is 250. The computed rows entry 1 delay_ms is 1.22. The computed rows entry 1 cancel_bw_Hz is 204. The computed rows entry 2 length_km is 500. The computed rows entry 2 delay_ms is 2.45. The computed rows entry 2 cancel_bw_Hz is 102. The computed rows entry 3 length_km is 1000. The computed rows entry 3 delay_ms is 4.9. The computed rows entry 3 cancel_bw_Hz is 51.1. The computed rows entry 4 length_km is 2000. The computed rows entry 4 delay_ms is 9.79. The computed rows entry 4 cancel_bw_Hz is 25.5. The computed segments_for_2000km_at_250 is 8. The study is a computation from stated assumptions, not a measurement, and its figures should be read at the precision those assumptions support. SIMULATED, NOT MEASURED.