Time domain reflectometry (TDR) measurement of soil volumetric water content relies on soil dielectric permittivity deduced from waveform travel-time analysis (TTA). Travel time analysis is reliable for non-dispersive and non-conductive media, but in dispersive and conductive media such as agricultural soils TTA-determined apparent permittivity represents complex interactions integrated over an uncertain frequency range. The apparent permittivity is known to be dependent on TDR instrument characteristics, transmission line configuration, and on the medium’s dielectric properties. Here we address the uncertainty in apparent permittivity determination through generation of synthetic waveforms and application of TTA. Synthetic TDR waveforms are constructed using a model describing the propagation of TDR signal through various cable-probe configurations embedded in media with different dielectric properties. Special attention is given to reducing numerical truncation errors associated with signal convolution. A primary advantage of this method is that individual factors contributing to signal deterioration and distortion such as relaxation phenomena and electrical conductivity, as well as cable losses, can be systematically isolated. The effective frequency range of importance to TTA for different cable lengths, probe configurations and sample dielectric properties is identified, and conceptual results compared with measurements.