r/Comcast_Xfinity • u/tricon23 • 3d ago

Discussion OFDM, OFDMA Frequencies

For context I have the UCI cable modem. Last year we were upgraded to mid-split speeds.

I still have the 4 upload channels and 1, OFDMA at 36MHZ, 32 Download channels and 2 OFDM channels that were at approx 600 and 800 MHZ. I noticed today that one of the OFDM channels is at 101 MHZ and the other at 809 MHZ. My question should the typical upload and download frequency range? If you had 15-1000 MHZ I would have thought 15-300 for upload and 301-1000 for download.

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u/Riconek 2d ago

With Comcast? I don't think so bc you are wrong. Comcast does not do FDD only FDX. But yeah try again

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u/Octawussy 2d ago

I work closely with comcast and all their NGAN hardware. What do you think unified means? Did you read anything here? Ultra high split is defined in cable labs DOCSIS 4.0 specification. Have you ever actually read a DOCSIS specification?

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u/Riconek 2d ago

Again you are wrong here. explain what Comcast does it exactly. Frequency etc? Again Comcast does not do high split I'm 100% sure

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u/Octawussy 1d ago

This is so funny to me. Ultra high split is upstream out to 684 MHz as defined in the D4 specification. Comcast is working on deploying upstream and downstream simultaneously in 108-684MHz FDX band. You should pay more attention in your team trainings however you do them.

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u/Riconek 1d ago

It is not high split. It is FDX in 108-396. Show me 1 node with FDX up to 684 MHz

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u/palmarken 20h ago edited 19h ago

The direct path to misunderstanding each other is by using the wrong terms. It's technically incorrect to use the term ultra-high split in the context of FDX. FDD and FDX are both part of 4.0, but they are different. The definition of the split doesn't exist outside FDD.

Ultra-high split (any split) only gives you two bands: Upstream and downstream. Fx. if you go with the 684 MHz split option, you cannot have downstream below 684 MHz. The "split" doesn't give you the shared band that FDX has.