  To achieve a distributed reflectivity measurement along an optical fiber, we
develop a simplified cost-effective configuration of optical correlation- (or
coherence-) domain reflectometry based on a synthesized optical coherence
function by sinusoidal modulation. By excluding conventional optical heterodyne
detection (practically, without using an acousto-optic modulator) and by
exploiting the foot of the Fresnel reflection spectrum, the electrical
bandwidth required for signal processing is lowered down to several megahertz.
We evaluate the basic system performance and demonstrate its high-speed
operation (10 ms for one scan) by tracking a moving reflection point in real
time.
