Earticle

The traditional detection methods are easily affected by noise. It is difficult to extract the useful signal from the power traveling wave which is submerged in a lot of noise. A method using digital lock-in amplifier is proposed for detecting the power traveling wave signal. The basic principles of the lock-in amplifier are studied. Virtual instrument language LabVIEW is used to design the digital lock-in amplifier. It is able to extract the corresponding frequency components of the power traveling wave signal. As the front panel and the flow sheet of the digital lock-in amplifier are presented, the design of each module is introduced in detail. The experimental research on detecting signals containing noise and not containing noise are carried out, respectively. The results of experiment show that the presented digital lock-in amplifier can accurately extract the corresponding frequency components of the power traveling wave signal. Moreover, with the increase of the noise amplitude, the root mean square error of the output signals varies little. The presented digital lock-in amplifier is able to cancel the effect of noise. Therefore, it is a powerful tool to detect and extract the power traveling wave signal.

This paper presents Long Reach Wavelength Division Multiplexing Passive Optical Network (WDM-PON) system capable of delivering downstream 100 Gbit/s data and upstream 100 Gbit/s data on a single wavelength. The optical source for downstream data and upstream data is CW Laser at central office and reflective semiconductor optical amplifier (RSOA) at each optical network unit. We use four RSOAs at each optical network unit for the 100-Gb/s upstream transmission. The operating wavelengths of these RSOAs are separated by the free-spectral range of the optical demultiplexer at the central office and remote node (RN) for demultiplexing the WDM channels. We extend the maximum reach of this WDM PON to be 100 km by using Erbium-doped fiber amplifiers at the RN. Bit error rate, receiver sensitivity were measured to demonstrate the proposed scheme. In this paper Long reach and large data service aspects of a WDM-PON is presented. The results show that the error-free transmission can be achieved for all WDM channels with sufficient power margins.