The Identification Technology Of Signal Wavelength And Modulation Mode On FSO

This paper is mainly about the research of signal wavelength and modulation mode identification on FSO.For the detection of optical signal wavelength, using the different respondence level between Si and InGaAs material to different optical wavelength to distinguish the wavelength of unknown laser. In this paper, we use the comparison of two APD modules’ output signals, when they exposed under the laser of same wavelength, to make a distinction between800nm,1064nm and1550nm. And for the laser near1550nm, calculating the accurate wavelength of laser based on the rotatory angle of laser’ vibration direction when it passed quartz crystal.And for the research of laser signal modulation mode, an identification method is proposed after analysis and comparison between the frequently-used modulation modes. That needs to collect several parameters, including statistics character and the performance of spectral line in signal PSD map, to recognize the modulation mode of unknown laser signal.