Oh I also did take a look at ITU G.9807. The text says the maximum reflectance at a single discrete incident is -35dB. That sounds weird. Reading all 300 pages might enlighten me, but I'm not doing that today 🙂
________________________________ From: Adam Moffett <[email protected]> Sent: Thursday, August 21, 2025 1:00 PM To: AnimalFarm Microwave Users Group <[email protected]> Subject: Re: 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]> 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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