High-precision time synchronization refers to the process of achieving and maintaining coordination among independent clocks via the exchange of local and remote time information. Existing analyses of digital receiver delay estimation often rely on an ideal continuous autocorrelation function (ACF), whereas practical receivers operate on discretely sampled intermediate-frequency signals. This paper analyzes how the digital autocorrelation function (DACF) can form delay-insensitive plateaus, referred to here as blind zones, and derives an upper bound on the minimum guaranteed resolvable code-phase step under rational sampling-to-code-rate ratios. Simulations and controlled SDR experiments using real IF signals are used to verify the predicted trend under the tested static laboratory conditions. The results provide guidance for sampling parameter selection and digital receiver design in high-precision wireless time synchronization systems.