JP2850244B2 - Optical space communication device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an optical space communication apparatus or system for performing communication by spatially propagated optical signals, and in particular, to optical space communication capable of stably realizing various functions. It relates to an apparatus or a system.

2. Description of the Related Art Conventionally, in an optical space communication system in which communication is performed by optical signals using free space as a transmission path, the transmitted optical signal itself is affected by the state of the atmosphere in the transmission path.

For example, there are fluctuations in beam position due to long-period vibrations of the building, irregular refractive index changes in the atmosphere, turbulence due to wind, etc., and fluctuations (scintillation) in received light power due to short-period atmospheric fluctuations.

In this way, the quality of the communication line is affected by the state of the atmosphere, which is the transmission path, and it becomes difficult to secure a stable line.Therefore, it is necessary to increase the beam diameter at the light receiving point or increase the diameter of the light receiving lens. Measures such as increasing the size are taken.

In addition, since optical space communication devices are often installed relatively outdoors, they are housed in a single, completely waterproof housing to prevent deterioration of the device due to changes in weather conditions. Measures have been taken. Furthermore, since it is difficult to secure a communication line unless the sending and receiving devices housed in such a housing are accurately opposed to each other, a mechanism for adjusting the vertical and horizontal angles is attached to such a housing. This angle adjusting mechanism is usually attached to the lower part of the device, and strict accuracy is required as the optical communication distance becomes longer.

Also, in the conventional equipment, various specifications of electrical and optical performance are specified by certain specifications, and to respond to applications other than those specifications, purchase a new device that meets the specifications. Need to be installed.

Further, when the device breaks down, the device is temporarily taken back to the factory, repaired, adjusted again, and installed and adjusted again.

Conventionally, as described above, the quality of the optical communication line has been ensured, the optical communication line has been adapted, the protection of the optical space communication device, the mounting accuracy has been ensured, and the maintenance has been performed.

[Problems to be Solved by the Invention] However, in the above conventional example, since the beam diameter at the light receiving point is widened, only a part of the total power of the light beam enters the lens on the light receiving side, and the light receiving efficiency is extremely high. Gets worse.
On the other hand, if the size of the light receiving lens is increased in order to increase the light receiving efficiency, the entire light receiving device becomes larger and heavier, and the angle adjusting mechanism for supporting the light receiving device also becomes larger. Therefore, the entire device including the angle adjusting mechanism becomes larger and heavier, which leads to an increase in cost and makes the device difficult for the user to handle.

In order to correct short-period light-receiving power fluctuations caused by scintillation, the electrical system of the light-receiving-side O / E (optical-electrical) converter has an automatic system with low NF (Noise Figure), high gain, and high response speed. Or the use of a gain control amplifier, but this is not without difficulty.

Also, when repairing the device, it is difficult to repair at the installation location due to its waterproof treatment as described above, etc.
Position adjustment with the O / E converter or the E / O (electrical-optical) converter is often required, and after all, the device must be returned to the factory once for repair, and all adjustments must be performed again. Of course, when the apparatus is re-installed, the angle adjustment of the entire apparatus is performed again.
Further, as described above, as the communication distance increases, strict accuracy is required for angle adjustment, so that it is difficult for the user to perform maintenance and inspection after installation, and there is a disadvantage that the user cannot easily handle the device. .

In addition, regarding the use form of the optical space communication device, the transmission distance ranges from a short distance of several tens of meters to a long distance of several km, and transmission signals include analog signals and digital signals. In the case of transmission by analog signal, from low frequency signal to high frequency signal like audio signal to video signal, and in the case of digital signal transmission, like signal from several Kbps to several 100Mbps. It covers a wide range with capacities from low to high.

In order to respond to such a large number of demands, it is conceivable to prepare a wide variety of products or to provide products with the highest performance and versatility over a wide range. It has disadvantages such as being too economical and increasing the price of the product.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an optical space communication apparatus which can be used for various purposes, is easy to maintain and install, and has stable performance, in order to solve the above problems.

[Means for Solving the Problems] In the present invention for achieving the above object, the light transmitting unit and the light receiving unit are each made to be one unit (though simply being defined as described above, The plurality of units do not always include both the light transmitting unit and the light receiving unit.) The light transmitting unit is provided by providing a coupling means in the unit itself and directly coupling a plurality of units together. And a plurality of units including at least one of the light receiving units (therefore, the plurality of units may be all composed of a light transmitting unit or a light receiving unit, or may include both a light transmitting unit and a light receiving unit) ) To form an optical space communication device,
The communication device includes a support unit having a mechanism for adjusting the angle of the whole of the plurality of units up, down, left, and right.

The light transmitting unit and the light receiving unit can be combined in various modes, and each unit may be composed of a plurality of separable functional modules.

The structure of the coupling means may be such that when a plurality of units are combined, the optical axis of each unit is automatically oriented in substantially the same direction.

[Operation] Since the light transmitting unit and the light receiving unit can be variously combined, various functions qualitatively and quantitatively can be achieved.
Stable communication can be secured.

For example, two-way communication, increase / decrease of light transmission power, wavelength multiplexing communication, spatial diversity for canceling fading, wavelength diversity, opposing transmission, tracking function of light-receiving communication device, etc., individually or in an appropriate combination at the same time. I can do it.

Further, if each unit is constituted by a plurality of function modules, the above functions can be easily and reliably achieved.

Furthermore, if the structure of the coupling means for combining a plurality of units is devised, simultaneously with the combination of the units, the direction of the optical axis of all the units can be the same direction with no adjustment or only a slight adjustment, Adjustment of the vertical and horizontal angles of the unit can be easily performed by providing means for supporting the unit.

[Embodiment] FIGS. 1 to 3 show a first embodiment of the present invention.
The figure shows an optical space communication apparatus constituted by combining the units 1 two-dimensionally, and FIGS. 2 and 3 show one unit 1.

In FIG. 1, a communication device constituted by combining units 1 has a gantry 2 as a support means having a mechanism for adjusting the angle of the communication device in the vertical and horizontal directions. This angle adjusting mechanism is composed of a gantry component 20 that rotates about an A-axis to adjust the angle in the vertical direction, and a gantry component that rotates about an axis extending in the vertical direction in FIG. It has a member 21.

2 and 3, the unit 1 is composed of modules (functional units) 3, 4, and 5, the module 3 is an optical system module including a lens system 30, and the module 4 is an E / O in a light transmitting system. The conversion unit, and in the light receiving unit, an E / O conversion or O / E conversion module including an O / E conversion unit.5.In the light transmission system, a modulation unit that modulates an input signal. /
This is a modulation or demodulation module including a demodulation unit that demodulates the electric signal converted by the E conversion unit into an original signal.

The optical system module 3 includes a light-shielding hood 31 for shielding disturbance light such as sunlight, a convex portion 32 formed on the upper surface to form a coupling means, a concave portion 33 formed on the lower surface to form a coupling means, FIG. A convex portion 34 is formed on the right side and forms the coupling means, and a concave portion 35 is formed on the left side of FIG. 2 and forms the coupling means. The inside of the light shielding hood 31 is painted black so that incident disturbance light is not irregularly reflected inside the hood. The respective parts 32, 33, 34, 35 constituting the above-mentioned coupling means are the lower surface concave part, the upper surface convex part, the left side concave part, and the right side convex part of the adjacent unit to come to the upper side, lower side, right side, left side of the unit 1, respectively. And serves to connect the units 1 in a separable manner.

The upper surface 36 and the lower surface 37 are precisely flattened so that the direction of the optical axis of each unit 1 is the same within a certain error range when the units 1 are assembled vertically and horizontally.
38a, 38b and side surfaces 39a, 39b of the concave portion 33 are also processed with appropriate accuracy.

Further, the surface 23 of the gantry 2 on which the unit 1 is placed
(FIG. 1) also has the same plane processing as the above-mentioned surfaces 36 and 37, and the same connecting means as the above-mentioned convex part 32 is provided on the contact surface 23 so that the gantry 2 and the unit 1 can be easily connected. The formed convex part is formed. The gantry 2 is further provided with a forked portion 24 that engages with the convex portion 34 on the right side surface of the unit 1 to more securely fix the unit 1.

Since the unit 1 is often installed outdoors in both the light transmitting system and the light receiving system, the unit 1 is connected to the optical system module 3.
Joint 40 with E / O conversion module 4 (light transmission system) or O / E conversion module 4 (light reception system), and E / O conversion module 4
The junction 50 between the modulation module 5 (light transmission system) or the O / E conversion module 4 and the demodulation module 5 (light reception system) has a completely waterproof structure so that water does not enter inside.

Further, in the light transmission system, the joint 40 is connected to the optical system module 3.
The optical axis and the positional relationship between the lens system 30 and the E / O conversion element (not shown) of the E / O conversion module 4, and in the light receiving system, the lens system 30 of the optical system module 3 and the O / E conversion module 4 O
Precise processing is applied to the corresponding portions of both modules 3 and 4 so that the optical axis and the positional relationship with the / E conversion element (not shown) automatically match or become predetermined with the joining. .

As described above, in order for the unit 1 to take a standardized form, even if any optical system module 3 and the E / O or O / E conversion module 4 are joined to form a light transmitting or receiving unit, The positional relationship between the optical axis and the lens system 30 and the E / O or O / E conversion element never shifts.

When the standardized unit 1 is combined two-dimensionally or three-dimensionally, the contact surface 23 of the gantry 2 is flattened as described above.
This is the vertical reference plane. The unit 1 that comes directly above the contact surface 23 fits the lower surface concave portion 33 into the convex portion of the contact surface 23 and
In this case, the side projections 34 and the side recesses 35 of the adjacent units 1 serve as a guide when the units are connected. Since the convex portion of the contact surface 23 and the side surface 39b of the unit lower surface concave portion 33 are precisely machined as described above, the horizontal blur angle of the optical axis of each unit 1 automatically falls within the allowable error range simultaneously with the combination. . In addition, the convex portion of the contact surface 23 and the concave portion
Since the side surfaces 39a of the 33 are also precision machined, the backlash in the depth direction of each unit 1 can be suppressed to within an allowable range. Thus, the optical axis of the unit 1 immediately above the gantry 2 is determined in substantially the same direction.

When the unit 1 is further stacked on these units 1, the upper surface 36 and the lower surface 37 of the unit 1 are flattened as described above, so that the concave portion 33 of the unit 1 fits into the convex portion 32 of the unit 1. Only by mounting, the optical axis of the unit 1 coming above is determined in substantially the same direction as that of the other units 1.

In this way, when combining the units 1 two-dimensionally as shown in FIG. 1, the contact surfaces 23 of the unit 1 and the gantry 2 and the units 1 are fixed, and the optical axes of all the units 1 are aligned in the same direction.

As described above, the gantry 2 on which the plurality of units 1 are mounted has the mechanisms 20 and 21 for vertically and horizontally adjusting the angles, so that the angles of all the units 1 can be vertically and horizontally adjusted while maintaining their mutual relationship.

In this way, when a plurality of units 1 constitute a space optical communication apparatus and secure a transmission path for space optical communication, each unit 1 and each of the modules 3, 4, and 5 may have different functions depending on the application. Can be. Regarding this, the first
This will be described with reference to a configuration example shown in FIG.

For the sake of explanation, numbers are assigned to the nine units 1 in FIG. 1 for convenience.

In the first example, at least one of the units 1 to 4 is used as a light transmitting unit, and the rest is configured as a light receiving unit, and a device having the same configuration is installed on the communication partner side. Communication is possible. The position of the light-sending unit can be arbitrarily selected from the range from to. Although the module configurations of the light transmitting unit and the light receiving unit have been described above, at this time, the optical system module 3 and the O / O
Since the E and E / O conversion modules 4 are the same standardized module, the directivity that the light transmission and reception light axes are the same is not lost. Now, assuming that one light transmitting unit is used and eight light receiving units are used, eight identical output signals are obtained as demodulated outputs of this device. By simultaneously processing (for example, combining) the demodulated signals, the reliability or stability of the communication line can be improved.

For example, when this output is a digital signal, the obtained eight pieces of parallel digital data are determined, for example, by majority decision to be one piece of digital data.

In the case of an analog signal output, for example, a signal having the best S / N is selected from the eight analog signal outputs, and that signal is used as an output signal. That is, the S / N of the eight analog signals may be constantly monitored, and the signal may be constantly switched to the best S / N signal for output.

Further, in the light receiving unit, an amplification module for amplifying the signal obtained by the O / E conversion module 4 may be attached instead of the demodulation module. In this case, a spatial diversity effect can be obtained by multiplexing the obtained eight modulated signals, or by selecting only high-quality modulated signals and multiplexing them, and demodulating the multiplexed signal. Can be

In this way, even if the beam position and the received light power of the transmitted beam fluctuate due to various atmospheric conditions and other conditions, a stable demodulated signal output is always obtained, and the quality of the communication line is improved.

A similar effect can be obtained even in a configuration in which one unit communication is performed using all of the units 1 as light receiving units.

As a second example, note the following. That is, in consideration of the distance of the transmission path and the transmission margin for obtaining a stable communication line quality, the light transmission power of the light transmission unit may be small at a short distance, and needs to increase as the distance increases. . Therefore, in view of cost performance, it is desirable that the optical space communication apparatus be capable of changing the light transmission power according to the distance. Therefore, it is conceivable that two or more of the units 1 to 2 are light transmitting units, and the number of light transmitting units that transmit the same signal is increased or decreased, and the light transmission power is stepwise increased or decreased as necessary. Can be As a result, a communication line having stable quality can be secured regardless of the distance of the transmission path. Also, various E / O conversion modules 4 using E / O conversion elements having different optical outputs are provided in a plurality of light transmitting units, respectively, and between the light transmitting units having different transmitting light powers according to the transmission distance. It is also possible to perform switching. By combining these two methods, the transmission distance and the transmission margin can be further fine-grained.

Third, there are two types of input signals on the light transmitting side: analog signals and digital signals, and the format of the optical signal that is modulated from the signal and transmitted through the spatial transmission path is analog signal. , AM-IM, FM-IM, etc., and digital signals include ASK-IM, FSK-IM, SPK-IM, etc.
It should be noted that there is a baseband-IM and the like common to both signals.

In order to cope with this, the input signal is an analog signal and the modulation method is AM or FM. A light transmission unit equipped with various modulation modules 5 or a modulation module 5 equipped with various modulation boards, or the input signal is modulated by a digital signal. Method is ASK, FS
A light transmitting unit equipped with various modulation modules 5 such as K, PSK and the like and a modulation module 5 mounted with various modulation substrates is prepared on the light transmitting side, and between such light transmitting units, as required according to the application and necessity. Perform switching.

Fourth, there is a wavelength division multiplexing transmission system for simultaneously transmitting these different signals. In this method, for example, an E / O conversion module 4 having E / O conversion element parts having different emission wavelengths is provided in each light transmission unit, and a plurality of light transmission units having different light transmission wavelengths are simultaneously operated. At this time, the optical system module 3 in each light transmitting unit
The optical axis and the positional relationship between the optical module and the E / O conversion module 4 do not break because both are standardized modules.

In this case, on the light receiving side, the O / E conversion module 4 is provided with a wavelength selection filter that allows a desired wavelength among various wavelengths to be transmitted, and this is coupled to the optical system module 3 to correspond to each wavelength. What is necessary is just to prepare a light receiving unit. Then, by joining the demodulation module 5 capable of demodulating the transmitted modulation signal or the demodulation module 5 mounted with various demodulation boards to the O / E conversion module 4, the original analog signal and digital signal can be demodulated. In this way, analog signals and digital signals can be modulated using various modulation methods and transmitted simultaneously by a wavelength multiplexing method.

Fifth, the wavelength multiplexing light transmission unit can transmit the same signal at different wavelengths simultaneously without transmitting different signals. In this case, on the light receiving side, the same modulation signal converted by the O / E conversion module 4 of each light receiving unit is multiplexed and demodulated, so that the effect of wavelength diversity can be obtained. At this time, since the light receiving units for each wavelength are spatially separated, the effect of spatial diversity can be obtained at the same time.

Sixth, all or a plurality of empty units are used as light receiving units, and by constantly detecting the O / E conversion output levels of these light receiving units, it is possible to detect the position fluctuation of the light transmission beam. Then, the information on the beam position fluctuation is returned to the optical communication on the light transmitting side, and the gantry 2 on which the light transmitting unit is mounted is automatically moved, so that tracking between the optical communication apparatuses on the transmitting and receiving sides can be performed. I can do it.

As means for transmitting the light transmission beam position fluctuation information to the light transmitting side, in the case of one-way communication, this position fluctuation information is digitized and transmitted via a modem using a public telephone network or a dedicated line in a company. Then, the gantry 2 on the light transmitting side is automatically moved by the digital data. In the case of two-way communication, the positions of both light transmission beams often fluctuate, so it is necessary to move both frames 2 at the same time. Therefore, as in the case of one-way communication, both beam position fluctuation information is digitized and transmitted bi-directionally via a modem using two public telephone lines or company dedicated lines, or two-way communication. The digital beam position fluctuation information is transmitted using an optical space communication line by using a wavelength multiplexing method or a frequency multiplexing method, and both frames 2 are moved by the transmitted data.

As described above, since the transmitting and receiving optical communication devices have a unit structure, the above-described functions can be achieved. However, a plurality of these functions can be simultaneously performed. In this way, an optical space communication device having a very wide degree of freedom and high versatility can be realized.

In the above embodiment, the light transmitting unit is a combination of the optical system module, the E / O conversion module, and the modulation module, and the light receiving unit is a combination of the optical system module, the O / E conversion module, and the demodulation module. However, the specifications of the device are determined when the optical space communication device is installed, and conversion of the specifications during use of the device is not so many as at the left. The optical unit is an optical system module and an E / O conversion module, or an E / O conversion module and a modulation module, and the light receiving unit is an optical system module and an O / E conversion module, or an O / E conversion module and a demodulation module. Is also good.

Further, in the above embodiment, when considering the distance of the transmission path and obtaining a stable quality of the communication line, it is possible to change the number of the light transmitting units and to use an E / O conversion element having a different optical output. The use of an E / O conversion module has been described as an example.
It is also possible to use a / E conversion element. For example, in the case of short-distance communication, a PIN photodiode is used as the O / E conversion element in order to make the circuit configuration relatively inexpensive, and in long-distance communication, a high sensitivity such as an avalanche photodiode is used. Use those. As a result, it is possible to cope with a finer grain that meets the desired specifications.

In the embodiment shown in FIG. 1, the unit 1 is three-dimensionally arranged in three rows × 3.
Although they are combined in a stage configuration, they may be two-dimensionally arranged as shown in FIG. Basically, m rows × n stages (m ≧ 1,
n ≧ 1), and m and n may be determined according to specifications.

Further, in the above embodiment, when the units 1 are combined, the units themselves are provided with connecting means to directly connect the units together. However, as shown in FIG. However, as for the vertical step, a method in which each contact surface 26 of the constituent member 25 of the gantry 2 and the unit 1 are connected and separated is also possible. As shown in FIG. 6, each contact surface 28 of the component 27 of the gantry 2 and the projection 29
The unit 1 can be fixed and the units can be separated from each other.

In the case of such a connecting means, it is not necessary to perform the flat processing of the upper surface of the optical system module 3 of the unit 1 as in the first embodiment, and the surface of the gantry 2 that contacts the optical system module 3 and the optical system module The lower surface of 3 may be flat-processed. Accordingly, the burden of processing the optical system module 3 can be reduced, and the projections of the optical system module 3 can be omitted.

Further, in such a configuration, since the units 1 are arranged at intervals, it is effective when trying to effectively catch a spreading light beam, or when performing spatial diversity.

In particular, in the embodiment of FIG. 6, in addition to the angle adjusting mechanism of the gantry 2, an effective function is exerted by providing a fine adjusting mechanism for adjusting the vertical and horizontal angles in each unit 1. This eliminates the necessity of the left mounting accuracy between the gantry 2 on which the unit 1 is mounted and the optical system module 3, thereby reducing the burden when the gantry 2 and the optical system module 3 are created.

[Effects of the Invention] As described above, according to the present invention, the optical space communication device
Since at least one of the light receiving unit and the light transmitting unit is arranged in plural, various functions can be easily and stably performed by changing the combination. In this way, it is possible to respond very finely to the specifications of the user.

In addition, if the unit is composed of a plurality of functional modules standardized in terms of electrical, optical, and dimensions, the above-mentioned measures will be further facilitated, and maintenance after installation of the apparatus and measures for changes in specifications will be extremely easy. It will be easier.

[Brief description of the drawings]

1 is an overall view of a first embodiment of the present invention, FIG. 2 is a perspective view showing a unit, FIG. 3 is a side view of the unit, FIG. 4 is an overall view of a second embodiment of the present invention, FIG. FIG. 5 is a front view of a third embodiment of the present invention, and FIG. 6 is a front view of a fourth embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Unit, 2 ... Stand, 3 ... Optical module, 4 ... O / E or E / O conversion module, 5 ... Modulation or demodulation module, 20, 21, 25, 27 ... Stand configuration Member, 23, 26, 28: Contact surface of the gantry, 32: Projection on the upper surface of optical system module, 33: Depression on the lower surface of optical module,
34: Side projection of optical system module, 35: Side recess of optical module

Claims (12)

(57) [Claims] 1. An optical space communication apparatus for performing communication using an optical signal propagated in space, wherein each of the light transmitting unit and the light receiving unit is a unit, and the unit itself is provided with coupling means to directly connect the units. By combining a plurality of units, an optical space communication device is configured from a plurality of units including at least one of the light transmitting unit and the light receiving unit, and the communication device adjusts the angle of the entire plurality of units up, down, left, and right. An optical space communication device, comprising: support means having a mechanism for performing the operation. 2. An optical space communication apparatus according to claim 1, wherein said one unit comprises a plurality of separable function modules. 3. The optical space communication apparatus according to claim 1, wherein said one unit comprises an optical system module, an E / O conversion or O / E conversion module, and a modulation or demodulation module. 4. The plurality of units include both a light transmitting unit and a light receiving unit so that bidirectional communication is possible.
Optical space communication device according to claim 1. 5. The transmission system according to claim 1, wherein the plurality of units include a plurality of light transmission units, and the transmission light power can be increased or decreased stepwise by increasing or decreasing the number of light transmission units transmitting the same signal. Optical space communication device. 6. The plurality of units include a plurality of light transmitting units having different transmitted light powers, thereby enabling switching between the light transmitting units to increase or decrease the transmitted light power. 2. The optical space communication device according to 1. 7. The plurality of units include a plurality of light transmission units having different light transmission wavelengths, and the light receiving side optical space communication device has a plurality of units having wavelength selection filters corresponding to the respective wavelengths. 2. The spatial communication apparatus according to claim 1, wherein wavelength division multiplexing communication can be performed. 8. The spatial diversity effect by including a plurality of light receiving units, wherein the plurality of light receiving units simultaneously receive optical signals propagating in space and combine the output signals of the respective light receiving units. 2. The optical space communication apparatus according to claim 1, wherein the optical communication apparatus is capable of obtaining the following. 9. The plurality of units include a plurality of light transmission units having different light transmission wavelengths, and the same signal is input to the plurality of light transmission units, and the plurality of light transmission units correspond to the respective wavelengths to a light receiving side optical space communication apparatus. By providing a plurality of light receiving units with the selected wavelength selection filter, each light receiving unit receives the same optical signal of each wavelength and combines the output signals of each light receiving unit to achieve both the wavelength diversity effect and the spatial diversity effect. The optical free space communication device according to claim 1, wherein the communication is enabled. 10. The plurality of units include a plurality of light receiving units, and means for monitoring each light receiving level of the plurality of light receiving units and detecting a deviation of a beam position of an optical signal propagating in space is provided. 2. The optical space according to claim 1, wherein an output signal of said detection means is returned to the optical communication device on the light transmitting side to provide a tracking function capable of automatically correcting a position on the light transmitting side. Communication device. 11. An optical space communication apparatus according to claim 1, wherein said coupling means is configured such that, when a plurality of units are combined, the optical axes of the respective units are oriented in substantially the same direction. 12. An optical space communication apparatus according to claim 1, wherein a plurality of functions among the functions described in claims 2 to 11 are obtained simultaneously.