The handheld Optical Time Domain Reflectometer (OTDR) is a portable, high-precision instrument designed to characterize and troubleshoot optical fiber links. Unlike benchtop OTDRs, its compact size and battery-powered operation make it indispensable for fieldwork—from fiber-to-the-home (FTTH) installations to telecom network maintenance. Its performance is defined by a suite of technical parameters that determine its ability to measure fiber length, locate faults (e.g., breaks, splices), and analyze signal loss. Below is a comprehensive analysis of the key parameter characteristics of handheld OTDRs, covering optical performance, measurement capabilities, operational features, and environmental adaptability.