RU18034U1 - OPTICAL OPTICAL COMMUNICATION SYSTEM - Google Patents

Description

OPTICAL OPTICAL COMMUNICATION SYSTEM

The utility model relates to open optical communication systems and can be used for two-way transmission of information between objects remote from each other without the use of electric wires and / or optical fibers, including with a large number of objects involved in the exchange of information, for example, when organizing an exchange using network technologies, or according to the point-to-multi-point scheme, that is, with two-way exchange of information between the base station and several subscribers.

A known optical communication system containing two terminals, each of which contains a transmitter in the form of a light source with modulation means and a receiver (see description of EPO application No. 0398596, H 04 B 10/10, 1990/1 /). The known system is used as a means to restore communication in the event of a failure of a portion of a fiber system and provides communication through a beam of optical radiation propagating in open space. A disadvantage of the known system is the limitation of its application, because it provides communication on only one channel.

A multi-channel optical communication system is known, comprising several transmitting devices made in the form of lasers with modulation means, a transmitting path in the form of an optical fiber.

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transparent to laser radiation, and several receiving devices (see the description of US patent No. 5589968, NKI 359/124, 1996/21}. An increase in throughput in this system is achieved due to spectral, temporal and code channel multiplexing. A disadvantage of the known system is its limited application and high cost, this is due to the use of optical fiber as a path transmitting optical radiation, which excludes the possibility of communication with objects that change their position in space, or requires work for proper laying of fiber optic cable, for example, underground or on poles (besides the fact that the installation is expensive, obtaining permission to lay, the so-called “right of passage, also requires significant costs.) In addition, the number of communication channels in this system is limited by the number of used for transmitting carrier frequency information.

A multi-channel open optical communication network is known, based on the use of a multicast distribution device (router) containing a scanner capable of sequentially directing a light beam through the atmosphere to one or more receiving devices from a plurality of receiving devices, and a lens raster, each of which lenses provides collimation of the beam, a receiving device directed to the corresponding lens or several receiving devices (see the description of US patent No. 5,786,923, NKI 359-172, July 28, 1998/3 /). The known communication network can also use radiation with different wavelengths, each of which is sent to a corresponding receiving device using a dispersing device. A disadvantage of the known system is that it does not fully realize the possibility of increasing the maximum transfer rate

information on atmospheric tracts. This drawback is very significant, since it is the atmospheric path, as a rule, that is the bottleneck in any communication network consisting of fiber and atmospheric sections.

The reasons, generally speaking, less than the fiber path, the throughput of the atmospheric path are that, unlike the fiber, the atmospheric channel is characterized by increased noise due to extraneous light (primarily solar radiation), as well as very significant signal power losses ( the absorption and scattering in the atmosphere, as well as the geometric factor due to the expansion of the beam in the atmosphere to diameters exceeding the diameter of the receiving apertures). The indicated weaknesses of the atmospheric tract require additional, in comparison with those used in the fibers, methods of channel compaction.

Closest to the claimed in its technical essence is an open optical communication system, known from the description of Japanese application No. 06303198, N 04 B 10/10, 1994/4 /. The known system contains several identical light emitting elements and several identical optical radiation receivers operating simultaneously. The system is designed to increase the speed of information transmission through the atmosphere due to the simultaneous use of several receivers and transmitters in order to form several (according to the number of receivers and their respective transmitters connected by optical beams) spatially separated channels (Spatial Channel Separation, PRK).

The disadvantages of the known device are also the limitations of its use and the complexity of the design. The complexity of the design is that in order for the channels to be

separated, it is necessary that each of the receivers receive radiation from the transmitter, addressed only to him. To ensure channel separation, each transmitter is equipped with a lens that forms a directed radiation beam, and the receivers should be located at a certain distance from each other so that they do not overlap the radiation beams from different transmitters. And this, in turn, imposes a limitation on the communication range, because any lens forms radiation beams with nonzero divergence. It should also be noted that in addition to the divergence due to the wave nature of light and the technical limitations inherent in any lens design, there is always light scattering, which creates “wings of the radiation pattern that are substantially wider than the divergence of unscattered radiation.

Thus, the known communication system is inconvenient for its use in servicing a large number of subscribers with address distribution of information, since each pair of subscribers should be located at a distance from each other sufficient to avoid the partial hit of the beam intended for each of them (including “wings” beam) to the receiving aperture of another subscriber. This requirement leads to a limitation of the communication range, an increase in size and complexity of the system, especially in the presence of a significant number of subscribers.

The inventive open optical communication system is aimed at simplifying the design, increasing the communication range with an increased number of served subscribers.

This result is achieved by the fact that the open optical communication system contains several simultaneously operating receivers and transmitters connected by beams of optical radiation, while transmitters with overlapping beams at the receivers are made with different carrier frequencies and / or modulation and / or coding, and receivers with the ability to select a signal addressed to each of them based on the carrier frequency and / or modulation and / or encoding.

Distinctive features of the claimed utility model are:

-performance of transmitters with beams overlapping at the receivers with different carrier frequencies and / or modulation and / or coding;

-performance of receivers with the ability to select the signal addressed to each of them based on the carrier frequency and / or modulation and / or encoding.

The implementation of transmitters with light beams overlapping at the receivers with different carrier frequencies and / or modulation and / or coding, and the performance of receivers with the ability to selectively receive only the signal addressed to each of them, allows serving a large number of subscribers remote over long distances from the transmitters.

Indeed, if such a situation arises that two closely spaced receivers of different subscribers are illuminated by the radiation of two transmitters, then if the transmitters operate on the same carrier frequency and use the same type of modulation, then each subscriber will perceive information not only addressed him, but also addressed to a neighbor. If we use the proposed communication system, then the neighboring receivers, even if each of them, due to the partial overlap of the light beams of the transmitter emitters on them, is illuminated by radiation from two or more transmitters, will only selectively perceive the information addressed to them.

It is significant that in the proposed system the number of subscribers can be significantly larger than the number of carrier frequencies and / or types of modulation, since only those transmitters whose radiation is blocked at the receivers should be distinguished by these characteristics.

It should also be noted that the carrier frequencies used to separate channels formed by partially superimposed light beams may not be the same as the frequencies used for spectral channel multiplexing (WDM) in an optical fiber preceding the atmospheric path. Considering the above limitations of the atmospheric path, the frequency broadening due to the information superimposed on the optical radiation in the atmospheric path will generally be less than in the fiber. Therefore, the carrier frequencies can be located closer to each other, however, avoiding the mutual noise (cross-talking) channels.

Another reason for allowing carrier frequencies to be closer than with WDM in the fiber is that the beams are only partially superimposed on the receivers, which in itself reduces the level of mutual channel noise. This also applies to the strictness of the orthogonality applied to partially overlapping bundles of codes. Thus, the specificity of the atmospheric path, generally speaking, requires for the optimal use of its bandwidth to use slightly different frequencies and codes than those that are standardly used for WDM, CDM (code compression), TDM (temporary compression) when transmitting information through an optical fiber.

The essence of the claimed system of open optical communication is illustrated by an example implementation and a drawing, which schematically shows its circuit diagram showing a partial overlap of light beams from different transmitters at adjacent receivers.

The optical communication system contains several transmitters 1 that have different carrier frequencies fi, f, f (or have different types of modulation - amplitude, phase, frequency, using one or another code) and several receivers 2 illuminated by the light beams of these transmitters and tuned each to receive one frequency - fi, f or f3 (or, respectively, for a certain type of modulation).

The system operates as follows. Each of the transmitters 1 transmits a signal that carries information for its receiver, subscriber 2, regardless of the operation of other transmitters on its carrier frequency or on the selected type of encoding or modulation. In this case, as shown in the drawing, the transmitters 1 illuminate the receivers 2 with a partial overlap of the beams. But since each of the receivers 2 is tuned either to its own frequency or to its own type of coding or modulation, each of them will selectively perceive the information addressed to it. The receivers and transmitters that make up the system, as well as the main components necessary for its operation, are selected from among those known from the prior art and having the required properties.

Claims (1)

An open optical communication system containing several simultaneously operating receivers and transmitters connected by beams of optical radiation, characterized in that the transmitters with overlapping beams on the receivers are made with different carrier frequencies and / or modulation and / or coding, and receivers with the ability to select the addressed to each of them a signal based on the carrier frequency and / or modulation and / or coding.