Method for automatically controlling received power in FSO system

Abstract

The invention discloses a method for automatically controlling received power in an FSO system. In a receiving device of a detector of a free-space optics communication system, the received light power is controlled by a method of automatically extending to control a received angular aperture; the control of the received angular aperture is realized by an aperture adjustable diaphragm; a light power sampling system samples the detector regularly, and sample values are input to a microprocessor, compared with a received light power range value stored in the microprocessor, and processed; when the received light power range value is smaller than a fixed value, the aperture of the diaphragm is increased, and when the received light power range value is greater than the fixed value, the aperture of the diaphragm is decreased; and a processing result is used to control a stepping motor to move the position of one end of the diaphragm so as to change the clear aperture of the diaphragm and control the received light power range. By adjusting the detection light intensity, the light power change range of the receiving end is reduced effectively and the stability and reliability of the system are further strengthened.

Description

1. Technical field [0001] The invention is a design for controlling the receiving optical power by adopting the method of automatically stretching and controlling the receiving aperture angle, and is suitable for the free space optical communication system (FSO). 2. Background technology [0002] Optical fiber communication and wireless communication are currently hot technologies, and free space optical communication system is the product of the combination of the two. [0003] A typical FSO system (such as figure 1 (shown) is mainly composed of optical receiving and transmitting antennas and terminal equipment, and corresponding relay equipment is added for long-distance transmission. After the laser at the sending terminal is modulated by the signal current, it emits laser light with a signal. After being transmitted through the atmospheric channel, it reaches the receiving terminal. After the optical signal is processed by the photoelectric detector, it is restored to ...

AI Technical Summary

Problems solved by technology

Although the optical receiver can have a dynamic range of about 20dB, it is difficult to ensure that the optical power is not overloaded

However, after encoding at the detector end, encoding judgment errors occur in a large range of optical power variation: when the received optical power value is large, the amplitude of the converted electrical pulse may not change due to the influence of the detector saturation effect, and it is easy to The detector causes damage; when the received optical power value is small, it will cause misjudgment in the identification circuit, resulting in an increase in the bit error rate

[0017] In summary, in the all-weather enhanced FSO communication system, due to the instability of the atmospheric space attenuation, the received optical power at the receiving end varies greatly, resulting in an increase in the bit error rate

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