RU2456746C2 - Optical communication system with blade lighting - Google Patents

Abstract

FIELD: information technologies.

SUBSTANCE: mobile device is arranged as capable of generating a transmitting and a receiving channels, and a stationary device is arranged with the possibility of a transmitting and a receiving channel, at the same time in the transmitting channel of the mobile device there is a set of laser light diodes arranged in the form of a ruler that forms a radiation indicatrix in the form of a "blade"; in the receiving channel of the stationary device there is one-dimensional coordinator of the mobile device position, besides, such coordinator comprises a bifocal lens and a CCD-ruler; in the transmitting unit of the stationary device in the front focal plane there is a ruler of laser diodes arranged as capable of switching one laser diode, the position of which complies with the direction towards the mobile device.

EFFECT: improved efficiency of information transfer in a wireless optical communication system.

13 dwg

Description

The invention relates to the field of optical communication and can be used in communication systems between various devices, both mobile and stationary.

Wireless (infrared, atmospheric) optical communication systems are designed to transmit data, voice and video. Like fiber optic systems, they use a laser beam to transmit a signal between transceiver devices. However, unlike fiber optics, the signal is transmitted through open air, and not through optical fiber. To receive and transmit a digital signal between wireless optical devices, direct visibility is required. In other words, there should not be any interference between them (such as, for example, trees). Wireless optical systems are used to create high-speed and secure communication channels that can be deployed over a very short period of time. In particular, the new systems of the TereScope 10 Giga series (http://newsdesk.pcmag.ru/taxonomy/term/7919) [1], which provides wireless atmospheric data transmission in 10 Gigabit Ethernet and STM-64 networks, can work at distances up to 800 m in favorable weather conditions. To ensure stable and reliable communication in all weather conditions, the distance between TS-10GE transceivers should not exceed 300 meters.

Wireless optical communication systems have already been installed in various companies, including hospitals, banks, telecom operators, municipal services and military departments in many countries of the world, offering wireless solutions of various levels of complexity. In corporate networks, these systems can be used to organize high-speed communication channels between offices, which avoids the cost of leasing leased lines. Wireless optical communication channels offer a serious alternative to fiber optics in cases where it is necessary to ensure the operation of high-speed applications (such as video conferencing), and the cost of laying the cable is too high. Another popular application of wireless optical systems is the organization of temporary communication channels during exhibitions, conferences, sporting events or for quick connection restoration in the event of a fiber-optic line accident.

The development of optical communication systems has been carried out for many years in different countries, in particular, in Russia, published applications for patents No. 98117651 [2] and 99113237 [3] can be mentioned. Original solutions are also presented in international applications, for example, PCT / GB2000 / 000456 [4] and PCT / US2000 / 041160 [5].

Closest to the claimed invention is a technical solution set forth in US patent No. 6,914,266 [6], which describes an optical communication system between two devices: mobile and stationary. The device diagram of such an optical communication system is shown in FIG. 1.

The optical communication line shown in FIG. 1 consists of a base station 2 and a mobile station 1, each of which contains an optical transceiver. The optical transmitter 2, 3 is a two-dimensional matrix of LEDs and is the same for both the base station and the mobile station. The optical receiver 5, 6 is a two-dimensional array of photodiodes and is also the same for the base station and the mobile station.

The optical communication system [6], chosen as a prototype, has either low efficiency or a low signal-to-noise ratio, depending on its settings, due to the construction of the optical circuit of the receiving channel. This fact does not allow you to confidently receive an information signal with a greater distance between the mobile and base station and / or with the deterioration of the atmosphere.

A design feature of the construction of the system of the transmitting unit of a stationary device leads to an increase in its dimensions, an increase in the complexity of its construction and the complexity of manufacturing, as well as increased energy consumption.

The use of radiation sources with a wavelength of more than 900 nm to transmit information reduces the usability of the communication system due to the difficulties encountered when pointing a mobile device to a base station. Additional restrictions are also imposed on the parameters of the radiation sources, due to more stringent requirements for radiation safety for the eyes in this spectral wavelength range.

The use of a two-dimensional matrix of LEDs or laser diodes as a radiation source in the transmitting channel of a stationary device does not allow increasing the speed of information transfer, due to the need to use a complex electronic circuit to control its operation.

The problem to which the claimed invention is directed is to develop such an optical communication system that would provide increased efficiency in operation, while the system should be simple in design to reduce costs, as well as energy-saving.

The technical result is achieved due to the development of an improved optical communication system, including two devices, namely:

- a mobile device that, apparently by a light beam, requests and receives information consisting of

- a transmitting channel including a lens in the focal plane of which is located an equidistant discrete set of laser diodes,

- a receiving channel consisting of a forming lens and a photodetector located one after the other for receiving information;

- a stationary device that detects a mobile device by the light beam, captures the request and transfers the requested information to it, which in turn also consists of

- a transmitting channel, consisting of one after another of the forming lens and a set of LEDs that provide a given angular deviation, angular divergence and the necessary modulation parameters of the light beam to transmit the necessary information to the mobile device,

- a receiving channel, consisting of a lens and a photodetector, for detecting and determining the angular coordinates of a mobile device;

with the aim of

- improving efficiency by reducing energy consumption and cheaper design, a line of LEDs has been introduced into the transmitting channel of the mobile device, forming an indicatrix of radiation in the form of a “knife”;

- cheaper design of the receiving channel of a stationary device it uses an optical 1D angle sensor (one-dimensional coordinator of the position of the mobile device) containing a bifocal lens and a CCD line,

- to simplify the transmitting channel of the stationary device and reduce its energy consumption without reducing the power of the information light beam received by the mobile device, the transmitting unit of the stationary device in the front focal plane of the lens contains a line of laser diodes, from which, with a known angular position of the mobile device, one laser diode is “lit”, the position of which corresponds to the direction to the mobile device.

Further, the claimed optical communication system is described in detail using graphic materials.

The optical communication system consists of two devices: a mobile device and a stationary device (see Figure 2). Mobile device 201 is an acceptor telephone that requests and receives information through a light beam. Stationary device 202 is a donor base station that detects a request by a light beam and transmits the requested information to device 201. Figure 2 presents a diagram of the relative position of the mobile device 201 and the stationary device 202. The axis of the device 201 and the axis of the device 202 are in the same plane.

The device 201 directs the axis of its transmitting channel 205 to the device 202 and transmits to it a request by the light beam to issue the necessary information. In this case, the receiving channel 203 of the device 201 is turned on and is ready to receive the requested information from the device 202.

When the receiving channel 204 of the device 202 extracts the request signal from the noise, the transmitting channel 206 is activated to transmit the requested information along the light beam towards the device 201. Further, the receiving channel 203 of the device 201 receives the requested information.

Thus, devices 201 and 202 have transmitting and receiving channels, namely, receiving channel 203 of device 201, transmitting channel 205 of device 201, receiving channel 204 of device 202, transmitting channel 206 of device 202.

The transmitting channel 205 is the simplest scheme - the lens 301, in the focus of which is located the radiation source 302 (Figure 3).

Thus, at the output of the transmitting channel, an indicatrix of light radiation in the form of a “knife” is formed. To quickly detect a mobile device in a wide range of deviation angles, the latter should have a wide radiation pattern, so only a small part of the energy enters the receiving system of a stationary device. After detecting and capturing the mobile device’s device stationary, to keep it on the optical channel requires a much smaller angle radiation pattern of the optical radiation of the mobile device, which can significantly reduce the energy loss of the mobile device, but for this the radiation pattern of the latter should vary depending on the operating mode, those. must be manageable. Such a scheme is implemented using a line of laser diodes, with which, changing the order of inclusion of individual laser diodes, it is possible to obtain radiation sources of different sizes and different positions relative to the optical axis of the system, and this will change not only the angular size of the radiation diagram, but also the direction of its axis , optimally adjusting it to the receiving system of a stationary device.

The receiving channel 203 is built on the basis of the simplest scheme - the lens, in the focal plane of which there is a photodiode with a large area of the photosensitive surface, to provide a large angular field for receiving the information signal from the device 202.

The receiving channel 204 should not only receive the request signal, but also measure the angular coordinates of the device 201. This will allow the axis of the information signal of the transmitting channel 206 to be directed in the direction of the receiving channel 203. Thus, the receiving channel 204 is a one-dimensional radiation angle sensor (FIG. .5). It consists of a bifocal lens, in the focal plane of which there is a line of photodiodes. A bifocal lens is used to match the scattering spot with the rectangular pixels of the photodiode array. Rectangular pixels are used to further enhance the signal-to-noise ratio.

The transmitting channel 206 is constructed according to the scheme consisting of a line of laser diodes located in the focal plane of the lens, as shown in Fig.6. After the sensor determines the receiving angle of the radiation from the mobile device by the sensor of the receiving channel of the stationary device, one laser diode is lit on the line of laser diodes, which corresponds to the direction in the line to the mobile device. Such a construction of the receiving and transmitting channels of the stationary device can dramatically reduce the power consumption of the stationary device and simplify its design.

As a preferred embodiment of the claimed invention, a system is proposed based on the following calculations of optical communication channels.

The transmitting channel 205 of the mobile device 201, as was justified above, consists of a lens, in the front focal plane of which there is a line of LEDs. The design scheme of the system is shown in Fig.7.

Initial data:

b = 0.30 mm is the size of the element of the line of laser diodes;

f '= 17.20 mm is the focal length of the lens;

D = 10.0 mm - the size of the entrance pupil of the lens.

The calculation results are presented in table 1 below:

Table 1 OS parameters of the transmitting channel of the mobile device. No. Surface type Radius Thickness Glass ⌀ mm one An object ∞ 15.0 Air - 2 Spherical surface 27,226 2.0 K8 10 3 Spherical surface -12,769 0,0 Air 10 four Aperture diaphragm ∞ ∞ Air 10 5 Picture ∞ - - -

The receiving channel of a mobile device consists of a lens, in the rear focal plane of which there is a photodetector. The organization diagram of the receiving channel is presented in Fig. 8.

According to the results of the design calculation, the following values of the geometric parameters of the elements of the receiving channel are obtained:

b = 0.40 mm - the size of the sensitive area of the photodetector;

f '= 11.45 mm - the rear focal length of the lens;

D = 8.0 mm - diameter of the entrance pupil of the lens;

θ = 1.0 deg - the angular width of the received light beam.

The beam path is shown in Fig.9.

The calculation results of the optical parameters of the elements of the receiving channel are given in table.2.

table 2 OS parameters of the receiving channel of the mobile device No. Surface type Radius Thickness Glass ⌀ mm one An object ∞ ∞ Air - 2 Aperture diaphragm ∞ 0,0 Air 8 3 Spherical surface 7,018 2.0 K8 8 four Spherical surface -32,963 10.0 Air 8 5 Picture ∞ - - -

The diameters of the surfaces 2, 3 and 4 of the optical system of the transmitting channel of the mobile device are 10 mm.

The receiving channel of a stationary device is formed from a bifocal OB lens, in the rear XZ focal plane of which there is a line of CCD photodiodes. A bifocal lens is needed to optimally fill the non-square sensitive area of a single photodiode in the lineup. The arrangement of the elements of the receiving channel is shown in Fig.10.

The initial and calculated parameters of the elements of the receiving channel are given below;

b = 0.3 mm - the height of the platform of an individual photodiode line;

- 1-е фокусное расстояние бифокального объектива;

- 1st focal length of a bifocal lens;

- фокусное расстояние цилиндрической линзы;

- focal length of a cylindrical lens;

- 2-е фокусное расстояние бифокального объектива;

- 2nd focal length of a bifocal lens;

D = 10.0 mm - diameter of the entrance pupil of the lens;

α = 20.0 degrees - the maximum angle of the received beam.

The beam path in the receiving channel of a stationary device is shown in Fig.11. The calculated parameters of the optical elements of the receiving channel are given in table.3.

Table 3 OS parameters of the receiving channel of a stationary device. Surface type Radius Thickness Glass ⌀ mm one An object ∞ ∞ Air - 2 Aperture diaphragm ∞ 0,0 Air 10 3 Spherical surface 22,883 1,0 K8 10 four Spherical surface 16,862 2.0 TF4 10 5 Spherical surface -15,502 1,0 Air 10 6 Cylindrical surface -514.0 1,0 K8 10 7 Flat surface ∞ 8.88 Air 10 8 Picture ∞ - - -

The transmitting channel of a stationary device consists of a lens, in the front focal plane of which there is a line of LEDs. The design scheme of the system is shown in Fig.12.

From design considerations, the following values of the geometric parameters of the system were calculated or selected:

b = 0.3 mm is the size of an individual laser diode;

d = 0.8 mm — grating period of laser diodes;

f '= 17.52 mm - the rear focal length of the lens;

D = 10.0 mm - diameter of the entrance pupil of the lens;

α = 20.0 degrees - the maximum angle of deviation of the light beam.

The beam path is shown in Fig.13.

The results of calculating the optical parameters of the channel are given in table 4.

Table 4 OS parameters of the transmitting channel of a stationary device No. Surface type Radius Thickness Glass ⌀ mm one An object ∞ 15.0 Air - 2 Spherical surface 14,337 2.0 TF4 10 3 Spherical surface -96,937 1,0 K8 10 four Spherical surface -121.878 0,0 Air 10 5 Aperture diaphragm ∞ ∞ Air 10 6 Picture ∞ - - -

The developed system can be successfully used in high-speed communication systems in the open space, using light radiation for data transmission, including for the exchange of information between mobile devices (mobile phones, personal digital assistants, etc.) and the base station (terminals, personal computers, laptops, etc.).

Claims (1)

A wireless optical communication system including a mobile device configured to form both a transmitting channel using a lens, in the focal plane of which there is an equidistant discrete set of laser diodes, and a receiving channel due to a focusing lens and a photodetector located one after the other, and stationary a device configured to form both a transmitting channel due to the forming lens and an array of LEDs, and a receiving channel due to the lens and a photodetector, while in the transmitting channel of the mobile device, the set of laser LEDs is made in the form of a ruler made with the possibility of forming a radiation indicatrix in the form of a “knife”;
a one-dimensional coordinator of the position of the mobile device is installed in the receiving channel of the stationary device, and such a coordinator contains a bifocal lens and a CCD line;
in the transmitting unit of the stationary device in the front focal plane of the lens there is a line of laser diodes configured to turn on one laser diode, the position of which corresponds to the direction to the mobile device.

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