Zit Seng's Blog

A Singaporean's technology and lifestyle blog

Single-Mode Fibre Patch Cord

Having done some home renovation, I took the opportunity to optimise my networking setup. Some of my gear were repositioned, and it ended up that my existing fibre patch cord for the OpenNet (now NetLink Trust) fibre broadband connection wasn’t long enough. I needed a new patch cord.

Fibre patch cords aren’t supposed to be expensive. But as with many other things, these things are often overpriced in retail channels. I was in a hurry, so I settled on buying from a seller on Qoo10. A 8 m length patch cord cost S$20. Not a horrendous ripoff, but yeah, it could be cheaper.

My bigger concern, of course, is if the patch cord work and is reliable. Well, I’ve put it on my broadband connection, and I can say that it works okay. Forgive my distrust, but like how it is with UTP patch cords and HDMI cables, they are often aggressively marketed with all sorts of inaccurate, sometimes false, claims.

This fibre patch cord does come with test specs: 0.12 dB insertion loss and 62.6 dB return loss.

I expect to see such things in my line of work. The above is a simple statement about the signal attenuation. For single-mode fibre, one would expect under 0.5 dB per km. 0.12 dB for a 8 m cable is quite high. It’s not clear, however, if the loss measurement includes the connectors. Connector loss can be about 0.3 dB. If connectors are included, this patch cord’s 0.12 dB insertion loss can be considered pretty good.

But either way, 0.12 dB loss can be considered negligible relative to the overall connection from exchange to my ONT.

Just some information to share: You might be told that fibre patch cords are fragile. They are made of glass optic fibre, after all. While you should handle them carefully, they aren’t exactly that fragile. You can safely bend the patch cords 90° around the corners of your cable path.

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