Looking through the specifications of the fiber optic adapter (flange), there are two numbers that cannot be avoided: insertion loss and return loss. One of them determines how much light is lost in the link, and the other determines how much light is reflected back. Only by understanding these two items can you judge whether a batch of adapters can be used on your link.

Insertion loss: nominal 0.3dB, which is probably high for a reason

The insertion loss of a qualified single-mode adapter is generally no higher than 0.3dB, and the commonly measured range is 0.1 to 0.2dB. If more than 1dB is measured on site, don't doubt the optical cable. Most of the reasons are sleeve wear, dirty end faces, or inconsistent grinding patterns at both ends. Adapters are consumable parts. The ceramic sleeve will become loose after being plugged and unplugged too many times, and the alignment accuracy will decrease. For batch ports that have been in service for many years, it is recommended to replace them in batches instead of replacing them one by one.

Return Loss: The higher the number, the better

Return loss expresses the degree to which reflected light is suppressed in dB. The UPC end face is usually no less than 50dB, and the APC bevel end face is no less than 60dB. The impact of reflection on digital links is relatively subtle, but for analog video optical transceivers and high-speed links, excess reflections will raise the noise floor and aggravate jitter. The specification sheet lists two batches of goods with a lower limit of 50dB and a typical value of 65dB. This is where the grade gap is reflected.

Converted to link: 0.5dB billed per connection point

The engineering budget generally leaves 0.3 to 0.5dB for each jump point. For a link jumpered twice by ODF, the adapter and plug combination takes up about 1dB. EB-LINK tests the return loss of the adapters one by one before leaving the factory for storage.Security video surveillance fiber optic transmission solutionFor this kind of multi-jump project, it is recommended to count the number of connection points according to the port table before checking the budget to avoid leaving adapter losses out of the account.