Time Domain Reflectometer for measuring liquid waste levels in a septic system

A Time Domain Reflectometer (TDR) level measurement device capable of generating and receiving electromagnetic waves for the measurement of waste water is presented. The primary objective is to measure the height of waste water in a tank and design an efficient measuring device. The TDR is based on the reflection mechanism, in which the time delay between the transmitted and reflected signals helps to determine the distance from the source to the surface of water, which is later used to calculate the height of water in the tank. The TDR is built using a 74AC14 IC, which is capable of producing pulse signals with very low rising and falling times that provide greater accuracy. Thus, the generated pulse signals are transmitted into the probe inserted in a tank. The total time taken by the pulse to travel the path to and from is calculated, which in return helps in calculating the height of the liquid in the tank. The functioning of the proposed TDR circuit and the biaxial probe is also tested in the laboratory.