Accurately locating specific fibers without interrupting service is a critical task during network installation, maintenance, and troubleshooting. This handheld digital fiber identifier enables non-destructive testing at any point on single-mode and multi-mode fibers. By injecting modulated signals at 1310nm or 1550nm (270Hz, 1kHz, or 2kHz) into one end of the fiber, it allows users to pinpoint and identify the exact fiber along the line. In addition to detecting signals, the identifier measures optical power levels and determines signal direction, ensuring precise results even in complex environments like active networks.