And only sissies use those cleaning pens, spit works just fine, right?

 

From: AF <[email protected]> On Behalf Of castarritt
Sent: Thursday, August 21, 2025 12:39 PM
To: AnimalFarm Microwave Users Group <[email protected]>
Subject: Re: [AFMUG] Help me Grok this - tolerance to reflected power

 

For PON specifically, I think you can run into interferrence issues from bad 
connections with inadequate return loss long before you have to worry about 
damaging the transceivers.  That's why everyone uses APC connectors for PON.

 

On Thu, Aug 21, 2025 at 12:20 PM Adam Moffett <[email protected] 
<mailto:[email protected]> > wrote:

It's PON, so yeah Bi-directional.  Different wavelengths for each direction.

 

  _____  

From: AF <[email protected] <mailto:[email protected]> > on behalf 
of Ken Hohhof <[email protected] <mailto:[email protected]> >
Sent: Thursday, August 21, 2025 1:08 PM
To: 'AnimalFarm Microwave Users Group' <[email protected] 
<mailto:[email protected]> >
Subject: Re: [AFMUG] Help me Grok this - tolerance to reflected power 

 

I assume this is not BiDi fiber?

 

From: AF <[email protected] <mailto:[email protected]> > On Behalf 
Of Adam Moffett
Sent: Thursday, August 21, 2025 12:01 PM
To: AnimalFarm Microwave Users Group <[email protected] <mailto:[email protected]> >
Subject: Re: [AFMUG] Help me Grok this - tolerance to reflected power

 

I think the "tolerance to reflected power" was the wrong direction to look.  
That seems like it's more about not damaging the equipment. I'll back out of 
the rabbit hole and just ask what I'm trying to figure out:

 

How much does reflectance actually hurt you on PON?  Google results are vague.  

 

Example: You generally need to have two connectors at the OLT (device to patch 
panel), and there's one connector at the ONT.  If you fusion spliced everything 
else so there were no additional reflective events, would there be a measurable 
BER or stability difference compared to having a coupler in the NID, 
connectorized splitters in the field, etc.

 

Another example: An AFL Fastconnect twist-on SC/APC field termination has -50dB 
reflectance according to the spec sheet.  A factory terminated connector or 
splice-on connector is -65dB.  How much does the twist-on hurt you?

 

 

-Adam

 

 

  _____  

From: Adam Moffett <[email protected] <mailto:[email protected]> >
Sent: Thursday, August 21, 2025 11:54 AM
To: AnimalFarm Microwave Users Group <[email protected] <mailto:[email protected]> >
Subject: Help me Grok this - tolerance to reflected power

 

 

Definition from ITU G.987:

3.3.15 tolerance to reflected power (transmitter): A transmitter parameter that 
characterizes the

maximum admissible ratio of the average reflected optical transmit power 
incident at the transmitter

to the average optical transmit power. 

 

If my average transmit power is +6dBm and the tolerance to reflected power is 
-15dB, then 6 - 15 = -9, so reflected power as strong as -9dBm won't harm the 
transmitter?  

Is it that easy or am I misunderstanding the definition?

 

-Adam

 

 

 

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