A state estimating device includes a pre-processing unit and an estimating unit. The pre-processing unit acquires data representing at one or more of a phase of a signal transmitted from a transmission unit of a transmission device and received at a reception unit of another transmission device via a transmission path, a reception strength, a reception quality, a voltage after conversion into an electric signal, and a signal processing parameter used in reception processing, and processes the acquired data into feature data to be used for state estimation. The estimating unit estimates a state of the transmission path, an abnormal state of the transmission unit, or an abnormal state of the reception unit, on the basis of the feature data.

An optical network including a processing device configured to receive from photodetectors, information indicative of a time period between loss of light received through a first optical fiber and loss of light received through a second optical fiber. The first optical fiber has a first latency and the second optical fiber has a second latency. The first optical fiber and the second optical fiber extend along a common path through the optical network: a first end of the path being defined by the photodetectors and a second end of the path being defined by a second location in the optical network. The processor is configured to calculate, based on the timing information and a difference in latency between the first optical fiber and the second optical fiber, a distance along the common path from the photodetectors to an event resulting in the losses of light.

A downlink data transmission method and apparatus, a storage medium, and an electronic device are disclosed. The method may include: determining a transmission delay, where the transmission delay includes a sum of an optical fiber transmission delay and a downlink processing delay from a Media Access Control (MAC) exit to an air interface (S102); determining a frame starting time of the MAC exit according to the transmission delay (S104); and transmitting downlink data according to the frame starting time (S106).

A novel system and apparatus for detecting and locating an external aggression on at least one optical cable of an optical communication system is provided. For example, a signal from a transmitter may be received and analysis may be performed to recover a state-of-polarization (SOP) associated with the signal. A first rapid polarization change that occurs may be identified, which may indicate that an external aggression has occurred on the at least one optical cable. A time offset between the first rapid polarization change and a second rapid polarization change may be used to estimate a location of the external aggression.

An optical node includes one or more Optical Add/Drop Multiplexer (OADM) devices which each form a respective degree connected to an associated Optical Multiplex Section (OMS) section of a cascaded optical network including a plurality of OMS sections; and a channel holder source connected to the OADM devices, wherein the OADM device is configured to detect a local fault affecting one or more traffic signals and switch to the channel holder source to provide a respective channel holder the one or more traffic signals with a same power level and spectral location such that the respective channel holder replaces a respective traffic signal at the OADM device which is a first switching port after the fault and such that all other OADM devices at other optical nodes downstream from the fault remain switched to the one or more traffic signals due to a presence of the provided respective channel holder.

A novel system and apparatus for detecting and locating an external aggression on at least one optical cable of an optical communication system is provided. For example, a signal from a transmitter may be received and analysis may be performed to recover a state-of-polarization (SOP) associated with the signal. A first rapid polarization change that occurs may be identified, which may indicate that an external aggression has occurred on the at least one optical cable. A time offset between the first rapid polarization change and a second rapid polarization change may be used to estimate a location of the external aggression.

The present invention discloses a high-precision and large-dynamic-range fault monitoring device and method for a WDM-PON. The monitoring device includes a WDM-PON optical network system and an optical network monitoring system. The optical network system includes an OLT I, a feeder fiber II, a 1n AWG III, a branch fiber IV, and an optical network unit V The optical network monitoring system includes an FP laser, a coupler, an optical coupling device, a photodetector, a signal acquisition and processing device, and an optical feedback device, where the FP laser is connected to the coupler; a large-coupling-ratio output end of the coupler is connected to an input end of the optical coupling device, and a small-coupling-ratio output end of the coupler is connected to an input end of the photodetector; the optical coupling device is installed on the feeder fiber II.

Disclosed is a method of extracting a faulty section of an optical path using a super resolution algorithm. The method includes generating a MUSIC spectrum by applying a MUSIC algorithm or an improved MUSIC algorithm to a received signal. Pieces of data on the received signal are divided into predetermined unit groups, and the MUSIC algorithm or the improved MUSIC algorithm is performed only on a unit group in which a signal corresponding to a reflection event occurs, among the predetermined unit groups.

A system for testing continuity of a cable assembly includes an optical time domain reflectometry (OTDR) device selectively coupled to an input connector of a cable and a design database storing cable data. The cable data indicates at least a length of the cable. The system includes a processor and memory in communication with the processor. The processor is configured to execute instructions stored on the memory which cause the processor to receive the cable data from the design database, receive OTDR data associated with the cable from the OTDR device, and calculate a distance-to-fault based on the OTDR data. In response to the distance-to-fault being less than the length of the cable, the processor determines that a connectivity failure has occurred with the cable and generates fault data indicating the connectivity failure.

Systems and methods include detecting a fast fiber transient on a span based on analyzing power data, wherein the power data is for any of optical wavelengths of traffic channels, optical service channel (OSC) wavelengths, and telemetry from a network element; and responsive to detecting the fast fiber transient, causing an optical time domain reflectometer (OTDR) trace on the span with a specific configuration based on the fast fiber transient.