Resolve Fiber Optic Module Transmission on Fiber Cable

The transmission of fiber optic module on the cable

The TOSA has a maximum emission light power in design and ROXA also has a certain sensitivity of the optical signal reception range in design. The transmission of fiber optic module on the cable is through a pair of OXAs on sfp fiber module, which is completed by the fiber the emitter (TOXA) and fiber-optic receiver (ROXA) two parts. Particularly, the signal reception range of ROXA is certain, which cannot be detected if the signal is too small and the ROXA light will be saturated, devices lossless failure if being too high.

Single-mode optical fiber connection test is different from multimode modules
LX, ZX, XD fiber optic module is designed specifically for long-distance fiber optic transmission, so the transmitting power of the transmitter is much higher compared to multimode module, the XD, ZX and EX are more prominent. As a result, the single-mode optical fiber connection test is different from multimode modules. When single-mode fiber module uses a jumper for close (local) tests, it is required to increase large enough attenuator in the fiber optic line to ensure being properly finished.
General attenuator claim is as follows:
1000LX (10-15KM): 5dm
1000XD (40-50KM): 15dm
1000ZX (70-80KM): 28DB
1000EX (100-120KM): 45db
The results of optical fiber under different cases
In the case of not using an attenuator for test, unless the optical module manufacturers have module reception sensitivity automatic adjustment function for the reception power design, otherwise, it might occur receiver receiving light saturation or critical saturation phenomenon. In the case of the receiver light-receiving light saturation, the outside of the optical fiber link will exhibit the case of bad connections; in the case of light-receiving critical saturation, the hair packet data transmission occurs. The emergence of the above two situations often make the user mistakenly think that the sfp optical module is defective, these two cases are also applicable to the case that the cable insertion decay boxing is too small to cause the light receiving signal exceeds the ROXA receiving range in the actual cable and fiber supporting use.

Another direct calculation method of transmission distance
Another direct calculation method of transmission distance: module transmission distance = the absolute value of (TOSA minimum transmit power-ROSA minimum receiving power) - fiber optic cable insertion attenuation (dbm). When selecting combination fiber-optic module, we shall consider the maximum received power of the optical signal should not exceed the ROSA maximum receiver sensitivity! If attenuator light line cannot be found at the test site, a simple method is to pull the insertion module jumper (SC / LC / ST / FC) out a little, until the device port link indicator just lights and will not burn out, then we can basically confirm that ROXA received optical signal is within receiver design range allowed by the device.

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