A system for locating the tip of a catheter inside a human body is provided. The system includes a housing； a sound emitter and a sound sensor housed in the housing； a waveform generator configured to generate a fixed waveform at a desired frequency and having desired characteristics and output the fixed waveform to the sound emitter； a peripherally inserted central catheter fluidly coupled to the housing and configured to propagate the fixed waveform toward a heart of a patient； a sound sensor housed within said housing, said sound configured to sense sound waves reflected from the heart as the peripherally inserted central catheter is progressed toward a heart of a patient； and a waveform analyzer operably coupled to the output of the waveform generator and input from the sound sensor, the waveform analyzer operable to determine the difference between the output and input.
