Media converter with asymmetric fibre converter

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neb

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#265460 22-Jan-2020 14:29

Someone just pointed me at some surplus media converters, SC/SC single mode, for which I have a vague plan to use them to electrically isolate some gear that's connected to outdoor sensors that's currently running over WiFi for the same reason. However I noticed that the connector is a weird asymmetric style where only the TX fibre is exposed and the RX one has a solid plastic cap over it:

Apologies for the bad image, done under flourescent lighting in an office. Anyone know what this is? Is it bidirectional on a single fibre? Why are there (apparently) RX and TX ports present when only one can be used?

Googling the part number, HTB-GS-03, leads to this which has the expected RX + TX connector, but also things like this, a clone with only the TX connector accessible.

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#2404664 22-Jan-2020 14:38

Oh, another nice thing about them is that they're powered off 5V, so I can run them from a UBEC rather than having to provide a seperate 9V or 12V power source outdoors.

littlehead

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#2404667 22-Jan-2020 14:43

I can't say for certain, but I would guess that it is most likely that whoever manufacturers these are just sharing a case/tooling on a model that uses both the RX and TX ports and it is cheaper to use that same case and put a cap on the RX port than create a brand new single port case. It is most likely that only the TX port will be actually connected to anything. If you can take it apart you could check this.

cyril7

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#2404700 22-Jan-2020 15:20

I recon its a BiDi converter (ie single SM fibre) hence one is blanked off, whats exact model number

Cyril

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#2404703 22-Jan-2020 15:22

As mentioned above it's probably just a manufacturing process. Retooling a different case for BiDi fibre no doubt costs $$ so they've decided against it.

And yes you can have both RX/TX over different fibres or BiDi (bidirectional) where TX and RX run at different wavelengths over the single fibre.

neb

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#2404706 22-Jan-2020 15:24

Hmm, so it's a half duplex converter? It would come with any length of pretty fancy (bend-insensitive, etc) fibre thrown in, but duplex cable, you can see some of it in the background of the shot that I was planning to grab.

So it looks like my options are either to find a different converter to suit the cable (SC/SC single-mode duplex with 5V power) or a different cable to suit the converter (SC/SC single-mode half duplex)?

I don't work with fibre much but would something like this do it?

sparkz25

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#2404709 22-Jan-2020 15:25

cyril7:

I recon its a BiDi converter (ie single SM fibre) hence one is blanked off, whats exact model number

Cyril

I'm with Cyril on this one, it looks like the RX is moulded to be blank, there should be some more information on the converter specifying the wavelength that the TX and RX are on.

Tx could be 1510nm and RX could be 1310nm or vice versa.

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sbiddle

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#2404712 22-Jan-2020 15:28

I'm unsure what your question is or what you want to actually know.

If you connect two of those media converters together with a SC cable you will get a connection. If you require plugging it into another media converter or SFP (I haven't used a media converter like that for years - I only use SFP's due to all the problems media converters can cause) it needs to be another BiDI SFP or media converter.

sbiddle

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#2404714 22-Jan-2020 15:29

There is no need for new cable, your existing cable will work fine.

cyril7

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#2404718 22-Jan-2020 15:31

Hi, its not half duplex, it will be full duplex, but on a single fibre, forward traffic on one wavelength, reverse on other, as Sparkz mentions standard wavelengths are 1510 and 1310nm

Cyril

neb

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#2404722 22-Jan-2020 15:36

cyril7:
I recon its a BiDi converter (ie single SM fibre) hence one is blanked off, whats exact model number

Claims to be a HTB-GS-03A, but it doesn't look like the one in the original manufacturer's photo. Data sheet is here.

cyril7

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#2404731 22-Jan-2020 15:43

Hi, yep BiDi, read last paragraph

Cyril

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#2404732 22-Jan-2020 15:43

Datasheet says:

"The transmission of a channel optical signals can be completed by single fiber. It has doubled in quantity of fiber data transmission compared with twin fiber type."

https://www.hexin-technology.com/netLINK_1000M_Single-mode_Single_Fiber_Optic_Ethernet_Media_Converter-Product-520.html

Interesting.

neb

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#2404737 22-Jan-2020 16:01

cyril7:
Hi, its not half duplex, it will be full duplex, but on a single fibre, forward traffic on one wavelength, reverse on other, as Sparkz mentions standard wavelengths are 1510 and 1310nm

Ah, OK, thanks! The data sheet claims 1310/1550nm, and further down "A transmitted optical wavelength 1310nm, receive optical wavelength 1550nm; B transmitted optical wavelength 1550nm, receive optical wavelength 1310nm".

Anyone happen to have a spare 10M SC/SC single-mode simplex cable lying around, to swap for an equivalent duplex cable?

cyril7

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#2404739 22-Jan-2020 16:04

https://www.fs.com/au/c/os2-9-125-single-mode-simplex-1082

Edit: you could also just split the duplex one you have, the two SC connectors are held in duplex by a simple bracket that is designed to come apart

Cyril

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#2404742 22-Jan-2020 16:07

neb: Anyone happen to have a spare 10M SC/SC single-mode simplex cable lying around, to swap for an equivalent duplex cable?

I'm still confused why you think you need a new fibre patch cable. The cables are the same, and 99% of fibre cables out there whether LC or SC simply have clips holding both the connectors together. Simply unclip the chis and you're sorted.

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