Why 3 wavelengths in a reflectometer?
Having an OTDR with the ability to measure at 3 wavelengths comes with a number of benefits. The first is the ability to fulfil customer orders to their specifications. Requirements for reflectometric measurements range from those where the customer expects measurements at 1310 nm and 1550 nm to those where only measurements at 1625 nm are expected (mainly measurements in larger operators' networks). The FWT-200-PON can handle any of these types of requests.Another benefit is the possibility of full diagnostics of the system being made. The additional 1625 nm laser makes it possible to detect any macro-bends in the system that would not necessarily manifest themselves with 1310/1550 nm measurements. The higher wavelength, due to occupying a larger area of the MFD in the fibre, is more sensitive to leakage at bends, resulting in increased attenuation. However, it is worth making measurements at lower wavelengths as well, since it is at these wavelengths that transmission is usually realized. In addition, the 1310 nm wavelength helps highlight fibre positioning problems (poor connectors, splices). To summarize, 3-wave measurement is a complete measurement and provides full information about the network.
