OTDR Signal Injection in Multistage PON Splitters

The patent segments the power splitter into multiple stages (e.g., first stage 1:4 splitter followed by second stage 2:2 splitters). The OTDR signal is injected at an intermediate point between stages, so it only passes through fewer splitters (e.g., one 2:2 splitter) instead of all splitters in the complete 1:32 configuration. This segmentation allows the signal to reach ONTs with sufficient strength for fault localization while still serving a large number of ONTs through the multi-stage architecture.

The patent makes a single OTDR device universal by enabling it to manage multiple PONs through the multistage power splitter architecture. The OTDR signal can be injected at intermediate points in the splitter hierarchy, allowing one device to access and diagnose faults in multiple different PON networks. This multi-functionality reduces operational costs by eliminating the need for separate OTDR devices for each PON while the modular splitter structure helps manage the complexity.

By injecting the OTDR signal at an intermediate point in the multistage splitter hierarchy, the patent segments the group of ONTs into smaller subsets. The signal reaches only a portion of the total ONTs (e.g., 8 ONTs instead of 32), so the back reflections combine from fewer sources. This segmentation preserves fault identification clarity while still reaching multiple ONTs, and the process can be repeated for different subsets to cover the entire network.