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Author Topic: Optical Fibre Patch Cable Parameters  (Read 422 times)

burakkucat

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Optical Fibre Patch Cable Parameters
« on: September 18, 2020, 06:11:09 PM »

A little earlier today I was looking at a 4.5m long, single-mode, patch cable which is terminated with SC/UPC connectors. Its yellow outer jacket states --

Corning Fiber (sic) Optical Cable 9/125 OS2 SM LSZH

There also appears to be a manufacturing batch number printed after the above string.

On the packaging, there is a printed label with a table of the measured insertion and return losses --

Connector        Insertion Loss        Return Loss
      A                   0.09 dB               55.3 dB
      B                   0.06 dB               55.4 dB

At a quick glance, the table shows reasonable values. Then a niggling thought developed that I don't fully understand what is involved . . .

It is a cable, consisting of one fibre, with two ends. As part of the manufacturing process, those two ends are plugged into some gubbins to automagically measure the cable parameters. Is the table telling me that --
  • With a standardised laser source at the A-end, a detector at the B-end observes an attenuation of 0.09 dB (the insertion loss) whilst another detector at the A-end observes a reflection (from the B-end) attenuated by 55.3 dB (the return loss)?
Then, logically "swapping ends", the process is repeated.
  • With a standardised laser source at the B-end, a detector at the A-end observes an attenuation of 0.06 dB (the insertion loss) whilst another detector at the B-end observes a reflection (from the A-end) attenuated by 55.4 dB (the return loss)?
Having just typed that out, I suspect that the answers are "yes" and "yes". But I would appreciate some "words from the wise", please.
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licquorice

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Re: Optical Fibre Patch Cable Paramters
« Reply #1 on: September 18, 2020, 07:14:49 PM »

Not sure about 'wise' , but yes and yes.
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burakkucat

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Re: Optical Fibre Patch Cable Parameters
« Reply #2 on: September 18, 2020, 07:58:11 PM »

Thank you.  :)
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burakkucat

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Re: Optical Fibre Patch Cable Parameters
« Reply #3 on: September 19, 2020, 04:59:28 PM »

Overnight, a thought came to me that there is no indication as to which end of the physical cable is "A" and which end is "B". Hence the label on the packaging, as printed, is somewhat pointless. For each parameter, why not just quote the arithmetic mean of the two measured values?

Thus for the patch cable, as a whole --

Insertion Loss: 0.075 dB
Return Loss:    55.35 dB
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