Re: [802.3_EPOC] RF Spectrum Ad Hoc Minutes
Steve and Jim
I agree with Jim points in the second paragraph below. Generally in view
the best filtering is no filtering meaning the complete ability to turn the
carriers off much like turning of the lights in a room. The 50 dB number
might be acceptable in the "white space" between channels but I don't
think it is good in channel and specifically analog channels that may still
exist. Residual RF energy particularly in and around the color subcarrier
will cause noticable beat issues in the picture.
Unfortunately I did not get back on the call before it ended yesterday but
while the call was in progress I called a close friend who is respondsible
for the manufacter of amplifiers and nodes. I asked what I might expect to
see in the field related to pilot carriers. He told me I would definitely
see a wide cross section of deployments with dual analog slope and gain
pilots, gain only pilots, QAM sensing pilots and cw carrier pilots in
currently deployed networks. He commented that the time frame of the
original deployment will be the best determinent of what we will see in an
operators network. So in my view, I would plan on a survey before an EPoC
deplyment is done to make sure I could tell the operator what the best
options are for his plant.
I guess that leads me back to not wanting to describe exclusion bands at
all but provide a general operational model that allows the operator to
decide how he wants to handle a conflict between an 802.3 bn carrier and a
carrier inside the coax which can't be moved or ingressing into the coax
causing an issue. In the latter case, I would think the operator would want
to fix the issue. In the former case, I would consider it "implementation
planning." ;-)
I'm not sure I understand the difference in the third paragraph either. I
think, in the current standard development, the channel is the channel: 192
MHz. The only option - read that as "choice" - the operator has is to
operate at cumulative 192 width or make the channel smaller in size with a
corresponding reduction in actual transmission capacity. The best example
is where we started with 1GE in 120 MHz. I'm not sure of bandwidth
variances beyond 192 MHz per se but
I suspect in the upstream the bandwidth is at issue because we haven't
really determined where the diplex filter edges need to be.
My thought at any rate....
Tom
On Wed, Dec 12, 2012 at 10:03 AM, Jim Farmer <jfarmer@xxxxxxxxxx> wrote:
> 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****
>
> ** **
>
> ** **
> ------------------------------
>
> <="" p=""> ****
>
> ------------------------------
>
>
________________________________________________________________________
To unsubscribe from the STDS-802-3-EPOC list, click the following link:
https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-3-EPOC&A=1