JPS6232730A - Space transmission optical communication system - Google Patents

Abstract

PURPOSE:To reduce the variation of a transmitting state by executing communication through two optical transmission lines modulated by the same information. CONSTITUTION:A signal supplied from a transmitter to an input terminal 1 is distributed by a distributer 2 and supplied to two light emitters 3a, 3b. The light emitters 3a, 3b emit optical signals 4a, 4b modulated by the supplied signals and the optical signals 4a, 4b are transmitted through space and detected by photodetectors 5a, 5b. The optical signals detected by the photodetectors 5a, 5b are transduced into electric signals, the electric signals are added by a coupler 6 and the added signal is supplied to an output terminal 7. Since the optical signals 4a, 4b are transmitted through the completely different pathes, the probability of the simultaneous variation of the two transmission lines is reduced and the variation of the transmitting state can be reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a spatial transmission optical communication system that performs communication by modulating light and transmitting the light in space. [Prior Art] Conventionally, several A spatial transmission optical communication system has been proposed in which an optical transmitter/receiver is installed at a point more than 10 meters away, and an optical propagation path is formed by the spatially transmitted light.

However, in the space through which light propagates, the refractive index, transmittance, and scattering state of the propagation path vary due to factors such as uneven distribution of water vapor, temperature distribution of air, and air convection. For this reason, communication quality is also affected by the propagation path, and in order to ensure stable communication, the optical system such as the lens used for the light emitting part and the light receiving part is made larger, and the diameter of the optical path that transmits the propagation path is increased. Measures such as these are being taken.

[Problem that the invention seeks to solve]

However, the automatic gain adjustment function requires a fast response speed and a wide dynamic range, which is often difficult to achieve, and increasing the diameter of the optical path increases the size of the optical system and becomes extremely expensive. There was a drawback that it became

[Friendly means of solving problems]

This invention aims to solve these drawbacks.

Communication is performed using at least two optical propagation paths.

[For production]

Fluctuations in communication quality are reduced.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention. In the same figure, a signal supplied from a transmitter (not shown) to an input terminal 1 is distributed by a distributor 2 and sent to two light emitters 3a and 3b.
supplied to Light emitter 3a.

3b is supplied and modulated with a ratio signal to emit nine lights 4a and 4b, and these lights 4a and 4b are transmitted through space.

5a and 5b are light receivers provided on the transmission paths of the lights 4a and 4b, and the light received by the light receivers 5a and 5b is converted into electrical signals, and the signals are added by a coupler 6.
The signal is supplied to and received by a receiver (not shown) via the output terminal γ.

In FIG. 1, light emitters 3a, 3b and a light receiver 5a,
Since the beams 5b are provided a predetermined distance apart, the secondary beams 4a and 4b are modulated with the same information and propagate through completely different channels. As a result, even if the propagation state fluctuates over −10,000 propagation paths,
The probability that the propagation states of other propagation paths will also change at the same time is very small.

The amount of variation in the propagation state can be kept small. It has been confirmed through experiments that this predetermined distance should be at least 1Ocrn, and Fig. 90 shows that the lights 4a and 4b sent out from the light emitter 3 also have a spread angle θ, which is proportional to the spread angle θ. Light receiver 5a,
This is an angle to ensure the spacing of 5b to the same extent as in the example of FIG. FIG. 3 shows a light emitter 3a.

Light 4a, 4b1&: emitted from 3b is an example in which the light is focused at an angle α at the light receiver 5, and this angle α is
The distance t between a and 3b is an angle that is to be maintained at the same level as the example shown in FIG.

Note that the above embodiment is an example of one-way communication, but the same applies to two-way communication, and the number of transmission lines may be two or more (it may be any number of transmission lines, and the number of communication lines between the light emitters or the light receiving The distance between the containers may be as long as the distance described in the example of FIG. 1 is maintained.

〔Effect of the invention〕

As explained above, in this invention, since communication is performed through at least two optical propagation paths modulated with the same information, the amount of fluctuation in the propagation state is reduced, and therefore the added automatic gain adjustment function is simple. It is economical because it only requires 20 seconds, and has the effect of increasing the stability of communication and increasing the communication distance.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIGS. 2 and 3 are block diagrams showing other embodiments. 2...Distributor, 3.3a, 3b...Light emitter,
4a, 4b---Light, 5, 5a, 5b---Photo receiver, 6---Coupler.

Claims (1)

[Claims] A spatial transmission optical communication system that performs communication by modulating light and transmitting the light through space, characterized in that communication is performed through at least two optical propagation paths modulated with the same information. Space transmission optical communication system.