Device for conducting position detection using modulation light beam and detection method

Abstract

Signal processing circuit is position-sensing detector with its four pins connected to I / V converter, multiplier, low-pass filter and A / D converter respectively in series. The four routes are connected to single chip in parallel. A / D converter is connected to feedback end of square-wave generator, and output end of square-wave generator is connected to input end of multiplier in each router. Detecting method is as following: modulated by square-wave in certain frequency, beacon light is transmitted at transmitting end. Following operations are carried out at receiving end: receiving modulated light by the position-sensing detector, its output is connected to I / V converter; output of the I / V converter and square-wave are input to multiplier; result from the multiplier through filter and A / D converter is converted to four routes, which are input to single chip to calculate position information. Feedback control and differential processing remove background noise and dark current.

Description

1. Technical field [0001] The invention relates to a device for detecting the position of an object, in particular to a device for detecting the position by using a modulated light beam and a detection method adopted by the device. 2. Background technology [0002] Free space optical communication technology (FSO) is a wireless communication method that realizes point-to-point communication through one-way or two-way transmission of laser beams. It has the speed of optical fiber communication and does not require a large initial investment in scarce resources such as spectrum. , so it has won people's favor, making it an important supplement for optical fiber communication and radio wave wireless communication. Its application fields involve backbone networks, access networks, and local area networks. It is also especially suitable for emergency communications, fast service provisioning, military security communications, and special-occasion communications. Its advantages ar...

AI Technical Summary

Problems solved by technology

[0004] In the current free-space optical communication system, the position-sensitive detector in the ATP device adopts the direct detection method in the position detection application. In order to improve the performance, it is generally used to add a filter to the optical lens part to filter out part of the background light. However, since the dark current of position-sensitive detectors is generally very large, the dark current of a 10×10mm position-sensitive detector at room temperature is 200nA, coupled with the influence of background light, the sensitivity of the system is only about -20dBm. Greatly limits the effective distance of position detection

The usual compensation method is to increase the emission power of the beacon light source laser at the transmitting end, which is limited by the performance and cost of the laser

In addition, in terms of signal processing, there is also a method of modulating the signal at the transmitting end to improve the detection sensitivity. However, this requires the receiving end and the transmitting end to work under a common clock, which is unrealistic in the space optical communication system.

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