It’s not much of an issue on PON as far as I can tell.    If you are running 
RFOG (analog cable added to the fiber) I think it’s a much bigger issue.   I 
don’t know of very many companies still running RFOG.

Mark

> On Aug 21, 2025, at 1:00 PM, Adam Moffett <[email protected]> wrote:
> 
> 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]>
> Sent: Thursday, August 21, 2025 11:54 AM
> To: AnimalFarm Microwave Users Group <[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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