  Long-range Rayleigh-based Distributed Acoustic Sensing (DAS) systems are
often limited in their sensitivity and bandwidth. The former limitation is a
result of the low backscattered power and poor \textit{dynamic-strain to
optical-phase} transduction efficiency. The latter constraint results from the
trade-off between range and scan-rate which limits the sampling interval to the
longest delay in the sensing fiber. Quasi-DAS (Q-DAS) can yield enhanced
sensitivity but may still suffer from low backscattered power and low scan-rate
for long-haul, many-sensor, systems. In this work we study the use of Perfect
Periodic Correlation codes for interrogating a long-haul Q-DAS system. It is
shown that judicious choice of the code parameters allows order of magnitude
increase in detection bandwidths and in the power reflected from each sensor.
