This article describes a pulsed thermal Time-of-Flight (TTOF) flow sensor system as two subsystems i.e., a pulsed-wire system and a heat flow system. The entire flow sensor is regarded system-theoretically as a linear time-invariant (LTI) system and is described by its transfer function or impulse response. The characterization of the thermo-fluid dynamic signals obtained by a pulsed-wire and by a heat flow is strived. Hence, the impulse response of both pulsed-wire and heat flow is analyzed according to the flow velocity. Experimental and theoretical results are compared in a flow velocity range in air between 0.1 m/s and 1.4 m/s.