Brillouin Optical Correlation Domain Analysis (BOCDA) offers high speed random accessibility along a sensing fiber,
because it can localize stimulated Brillouin scattering at an arbitrary fiber position. By using this function, simultaneous
dynamic strain measurement at arbitrary selected multiple points along the fiber was achieved. However, measurement
accuracy was restricted due to performance limitation of lock-in-amplifier in the system. This paper reports a new system
which uses I/Q demodulator instead of the lock-in-amplifier. Measurement accuracy was improved.