The invention discloses a system for the bidirectional communication of digital data through the visible light spectrum, in an unconfined medium which uses two devices for supplying electrical current, regulating the voltage, converting the negative voltage, amplifying the signal, transmitting the signal to an LED, receiving the signal, finally converting the signal and transmitting the digital signal wirelessly to an end device, as specified in the description, and which, as a result of its characteristics of innocuity, privacy, low cost, higher power, savings in energy, interactivity, duality of use and extension of useful life of the devices, has a wide range of use in various fields in the industry such as: health, medicine, the military, education, training, tourism, gadget production, to name just a few.

This invention solves the problems of connection, privacy and frequency amplitude of data transmission that are found in existing connections such as Bluetooth and Wi-Fi.

A transmission device is implemented in a first node in an optical transmission system in which a frame is transmitted from the first node to a second node via an optical interface. The transmission device includes a decision unit that decides whether a type of a first error correction code used in the first node is the same as a type of a second error correction code used in the second node. When a type of the first error correction code is the same as a type of the second error correction code, the transmission device transmits the frame to which an error correction code used in the first node is added to the second node without terminating the error correction code.

A transmission device is implemented in a first node in an optical transmission system in which a frame is transmitted from the first node to a second node via an optical interface. The transmission device includes a decision unit that decides whether a type of a first error correction code used in the first node is the same as a type of a second error correction code used in the second node. When a type of the first error correction code is the same as a type of the second error correction code, the transmission device transmits the frame to which an error correction code used in the first node is added to the second node without terminating the error correction code.

A wide-field telescope and focal plane array (FPA) that look at Earth and satellites in low- and medium-Earth orbit (LEO and MEO) from a satellite in higher orbit, such as geostationary Earth orbit (GEO), can serve as a node in an on-demand, optical multiple access (OMA) communications network. The FPA receives asynchronous low-rate signals from LEO and MEO satellites and ground stations at a signal rate determined in part by the FPA frame rate (e.g., kHz to MHz). A controller tracks the low-rate signals across the FPA as the signal sources orbit Earth. The node also includes one or more transmitters that relay the received information to other nodes via wavelength-division multiplexed (WDM) free-space optical signals. These other signals may include low-rate telemetry communications, burst transmissions, and continuous data relay links.

A wide-field telescope and focal plane array (FPA) that look at Earth and satellites in low- and medium-Earth orbit (LEO and MEO) from a satellite in higher orbit, such as geostationary Earth orbit (GEO), can serve as a node in an on-demand, optical multiple access (OMA) communications network. The FPA receives asynchronous low-rate signals from LEO and MEO satellites and ground stations at a signal rate determined in part by the FPA frame rate (e.g., kHz to MHz). A controller tracks the low-rate signals across the FPA as the signal sources orbit Earth. The node also includes one or more transmitters that relay the received information to other nodes via wavelength-division multiplexed (WDM) free-space optical signals. These other signals may include low-rate telemetry communications, burst transmissions, and continuous data relay links.

Systems and methods for identification and demodulation of complex signal formats are disclosed. In an example embodiment of the disclosed technology, a method includes identifying the signal's frame (or pattern) length, identifying the various modulation formats that compose the frame, determining the ratio of the various modulation formats in the frame, and determining the actual pattern arrangement in the frame. Further, a method can include comparing the determined arrangement to reference patterns to determine the complex signal format.

A transmitter can include a laser operable to output an optical signal; a digital signal processor operable to receive data and provide a plurality of electrical signals based on the data; and a modulator operable to modulate the optical signal to provide a plurality of optical subcarriers based on the plurality of electrical signals. One of the plurality of subcarriers carries first information indicative of a first portion of the data in a first time slot and second information indicative of a second portion of the data in a second time slot. The first information is associated with a first node remote from the transmitter and the second information is associated with a second node remote from the transmitter. A receiver as well as a system also are described.

An optical assembly includes a carrier plate, a light emitting element and a lens component disposed on the carrier plate, and a securing block. The securing block has a first surface and a light-passing portion that are located on an optical path of an output light from the light emitting element. The lens component includes a lens portion and a connecting portion. The lens portion is located on the optical path. The connecting portion has a second surface facing the first surface of the securing block. A bottom surface of the securing block is bonded to the carrier plate. The lens component is secured onto the carrier plate by means of bonding between the second surface and the first surface of the securing block. A clearance space is present between the lens portion and the light-passing portion so that the lens portion does not contact the securing block.

An optical assembly includes a carrier plate, a light emitting element and a lens component disposed on the carrier plate, and a securing block. The securing block has a first surface and a light-passing portion that are located on an optical path of an output light from the light emitting element. The lens component includes a lens portion and a connecting portion. The lens portion is located on the optical path. The connecting portion has a second surface facing the first surface of the securing block. A bottom surface of the securing block is bonded to the carrier plate. The lens component is secured onto the carrier plate by means of bonding between the second surface and the first surface of the securing block. A clearance space is present between the lens portion and the light-passing portion so that the lens portion does not contact the securing block.

A method and apparatus is described for estimating a local oscillator frequency offset (LOFO) of a received optical signal in a coherent optical receiver. The method includes receiving a signal by the coherent optical receiver; digitally shifting a spectrum of the received signal according to one of a plurality of frequency shifts within a first range; equalizing each shifted signal based on a hybrid shifted filter response of a receiver driver, the hybrid shifted filter response is based on a combination of a linear shifted response and a circular shifted filter response of the receiver driver; calculating a difference of power between two sides of a spectrum of each equalized signal, the power for each side of the spectrum being calculated within a first area centered around a frequency corresponding to half of a baud rate of the received signal; determining a minimum power difference among the plurality of frequency shifts within the first range; and estimating the LOFO based on the minimum power difference.