Optical Fiber Network Test Method of an Optical Frequency Domain Reflectometer

An optical fiber network test method of an optical frequency domain reflectometer (OFDR), wherein comprising:

• a linear frequency scanning signal producer, wherein the frequency modulation rate of the produced wavelength is continuously linear variation frequency modulation signal;
• a DFB laser light source, which the linear frequency scanning signal producer is to produce the wavelength of the signal of the DFB laser to modulate the light signal, thus produce the incoherent optical frequency modulated continuous wave (I-OFMCW) signal as the monitoring optical signal;
• an optical circulator, which the optical circulator transmits the monitoring optical signal of DFB laser light source into the optical selector, thus separates the light and accept the reflected monitoring optical signal;
• a photodetector, which the photodetector receives the reflected monitoring optical signal from the optical circulator into electrical signal and enlarges the electrical signal;
• a band-pass filter, which the band-pass filter filters the electrical signal received from the photodetector to get the monitoring-required the electrical, thus the noise is diminished and the feed through event of mixer is prevented;
• a mixer, which the mixer is the transmitted optical frequency modulated continuous wave signal and the reflected optical frequency modulated continuous wave signal examined by the photodetector;
• a low-pass filter, which the low-pass filter filters out the high frequency noise and the harmonic noise signal, meanwhile only the low frequency beat note monitoring signal is passed;
• and
• a signal processing unit, which the signal processing unit makes the spectrum analysis on the beat note monitoring signal filtered by the low-pass filter, thus the analysis results is used to control the computer's monitor and alert and calculate the breakingpoint.