Re: [802.3_EPOC] RF Spectrum Ad Hoc Minutes
Thanks Steve. Since we are not meeting again for a while, and since my feeble mind cannot retain information very long, maybe I should register a few comments now.
Regarding the minutes, there seems to be an implied concept, which I intended to bring up on the phone but forgot (I was triple-tasking during the call, unfortunately), that we would generate signals in exclusion bands, then filter them out. I see us simply turning off generation of these signals, so that there will be no noise contribution at all from the exclusion band, except maybe to the extent that there is limited filtering of adjacent carriers that ARE turned on. Someone seemed to suggest that we could expect 50 dB of attenuation of these signals, which is a pretty good number, though I'd like to understand better how the spectrum would look. Also, there is a note that in dual pilot systems, both pilots may be within the 192 MHz passband. I doubt that the two pilots would be this close in frequency, but assuming several 192 MHz wide bands dedicated to EPoC, then it is certainly possible that each pilot will fall into one of our bands. It is true that most all amplifiers out there use an analog carrier as a pilot, though some recently-deployed amplifiers may use a digital carrier. I would expect these to need either a 4 or 6 MHz exclusion band in order to function normally. Fortunately we don't have to have much attenuation in order to let the pilot work normally, but we do have to have on the order of 50 dB attenuation I order to provide a good carrier-to-noise ratio for analog signals. I'm not sure how many analog signals will exist by the time this system gets deployed, but some probably will still be deployed.
Regarding the open issues, I'm still not clear of the distinction (and need) between mandatory and optional FDD downstream channels, but maybe it'll get through my thick skull one of these days. I suppose it has to do with frequency. The upstream FDD bands are curiously wider than 192 MHz, and not by a consistent amount. Ditto for the TDD bands. I'm not sure how much we need to be specifying band edges, since the industry is going to do what it sees as most beneficial. We may want to include text that says that while certain bands are suggested, use of other frequency bands is not a violation of the specification. Finally, there seems to be an inconsistency between "Possible Rules" and "Recommendations," in that "rules" has struck the note about exclusion bands being to control ingress, while that language remains in the "Recommendations."
Thanks, and Merry Christmas to all.
jim
Jim Farmer, K4BSE
Chief System Architect,
FTTP Solutions
Aurora Networks
1220 Old Alpharetta Rd.
Ste. 370
Alpharetta, GA 30005 USA
678-339-1045 (office)
678-640-0860 (mobile)
jfarmer@xxxxxxxxxx
From: Shellhammer, Steve [mailto:sshellha@xxxxxxxxxxxxxxxx]
Sent: Tuesday, December 11, 2012 4:46 PM
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: [802.3_EPOC] RF Spectrum Ad Hoc Minutes
All,
Attached are the minutes from today's call. Also attached is R4 of the RF Spectrum Open Issues List. The a schedule conflict next week and the upcoming holidays, our next call will be in January.
Steve
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