12TESTESFONTE DE LUZ VISÍVELPOWER METER E FONTE DE LUZOTDR
13Testes manuais Primeiro nível de teste Existe luz? Quanta luz? The power meter tells you if you have light coming out of your fiber, and how much. If you set the reference level of the power meter to the output level of the transmitter, it's a simple matter of connecting the power meter to the end of the fiber and finding the loss of the fiber. It is the first line offense for troubleshooting. It is analogous to the DMM in electrical troubleshooting. If you find light entering the fiber and none exiting, then it’s time you went a step further. It’s time for an OTDR.The OTDR tells you what is wrong with the fiber. The power meter starts before that, telling you if the problem is the electronics or the cable.
14Testes Ópticos – Portáteis (Power Meter) Transmissor de PotênciaMedidor de PotênciaPerda no SistemaThe most common test is done with the power meter. The first test is measures transmitter power. Confirm the power level is within specification (maybe even just confirming that it will put out light). In installation, an optical light source is used in place of the transmitter or where you want a stable light level. Transmitter power is usually measured in dBm, the power level referenced to a 1milliwatt power level.The second test takes the results of the first power level and compares it to the power level at the receiver end. The difference is the system loss, the amount of attenuation over the entire system. This will vary from the OTDR system measurement, in that the OTDR cannot measure the open connector at the end. In the power meter test the power meter is connected at the end.Sometimes a light source and power meter together is referred to as a Loss Test Set.TransmissorReceptor
15OTDR Testador de Cabos Ópticos Optical Time Domain Reflectometer Reflctômetro Óptico no Domínio do TempoTestador de Cabos ÓpticosVisualiza o cabo e seus eventosAnalisa, faz medidasDocumenta os eventosThe TekRanger 2 is a mini-OTDR, Optical Time Domain Reflectometer. These are smaller, more portable versions of traditional OTDRs.TekRanger 2, like other OTDRs, look at cable reflections to test fiber optic cable. By looking at these reflections, from one end of the cable, you can use the TekRanger 2 to see the cable, events such as splices, connectors, bends, and make precision measurements. This helps you test your system to make sure the cable and connections were installed properly and later test for system degradation. If a cable system failure does happen, the TekRanger 2 lets you quickly and easily locate the failure.The TekRanger 2 lets you locate and measure cable events. Events are the network components such as end connectors, splices, fiber sections. They can also be items created by installation problems and stress: bends, breaks, and cable stress.
16Os Testes Distância Perda na Fibra Perda no Evento Perda no Lance You passed the connector test (in most cases you don’t even see it). Now it’s time for the actual measurements. The TekRanger 2 will test the fiber, show the waveform, mark the event locations on the waveform, and create the event table. You have the test results and can read the measurements. So, what are the basic measurements?(see list on slide)These are the major reasons for having an OTDR. The five basic tests of fiber. They show nearly every feature of a fiber. If we reduce these features to common denominators, we see we're actually looking at backscatter levels and reflections. Other instruments may come close to measuring some of these, but only the OTDR can do them all with the high accuracy the fiber communications industry demands.
17Two important factors in documenting fiber are the loss from one end to the other (link loss), and the length of the fiber (distance). All of these measurements are easy with an OTDR. Another useful measurement becoming more important in high speed communication is reflectance (sometimes called event return loss).Reflectance is light that is not making it to the receiver because it is being returned or reflected back towards the transmitter. If it is being returned, three bad things are happening. Obviously the first is that the light is not reaching the receiver. The second is the returning light is probably going to reflect off the transmitter connector or laser, and take another round trip down the fiber. This is going to look like false data. And false data we can label as nothing more than noise. The third problem is that the returning light can affect the laser operation, causing jitter, or even laser “chip” where the laser fires when it should not.In digital systems this is manifested as an increase in the bit error rate. In analog systems such as television, it appears as sparkle, or snow.Typical reflectance specifications are: dB for OC192-55 dB for OC48