  Probe pulse preparation techniques play an important role for fiber-optic
sensing. In this work, we investigate a setup for distributed sensors based on
phase-sensitive optical time domain reflectometry ($\Phi$-OTDR) with the use of
an erbium doped fibre amplifier (EDFA). In our $\Phi$-OTDR setup with pulse
mode EDFA, we reveal a regime providing us both sufficiently large
amplification of the probe pulse power together and adequately small probe
pulse distortion. We then show that the use of pulse mode EDFA is a
cost-effective solution, which allows one to avoid nonlinear effect and ensure
sufficient sensitivity of the setup.
