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HeadendJoe

@comcast.net
reply to koitsu

Re: What to do about 11 weeks of node/network problems?

He could have had the headend techs check the transmitter for your node. They could then see whether or not those last two QAMs had MER/BER issues or if the signal from the NSG was degraded on those last two QAMs. If he truly saw the problem at the headend for your node, then that means those last two QAMs are degraded at the NSG because of a faulty card. A simple card swap at the headend and it's fixed. However, I doubt that's the problem or else it would have been fixed already. So, honestly I'm not sure what he meant there.

What you call "line tech" is what Comcast calls "Maintenance Techs". Maintenance techs do have the ability to walk the line with sniffer guns to locate where interference is entering the plant or where signal is leaking. I don't know how CSRs dispatch calls these days, but next time you call in, specifically request that you want a maintenance tech or a CommTech 5 tech to come diagnose an issue with the plant.

Also still contact the LFA and report the problem. Municipalities love fining cable companies for not being in compliance with maintaining their plant. Fines tend to jump start maintenance efforts.


EG
The wings of love
Premium
join:2006-11-18
Union, NJ
kudos:10
said by HeadendJoe :

I don't know how CSRs dispatch calls these days, but next time you call in, specifically request that you want a maintenance tech or a CommTech 5 tech to come diagnose an issue with the plant.

Isn't it basically their S.O.P. that the phone reps can not do this and that only the premise facing techs can escalate an issue to the maintenance / network dept.


koitsu
Premium,MVM
join:2002-07-16
Mountain View, CA
kudos:23
said by EG:

said by HeadendJoe :

I don't know how CSRs dispatch calls these days, but next time you call in, specifically request that you want a maintenance tech or a CommTech 5 tech to come diagnose an issue with the plant.

Isn't it basically their S.O.P. that the phone reps can not do this and that only the premise facing techs can escalate an issue to the maintenance / network dept.

This is correct. The CSRs will open up a new CR (ticket/case) and will only schedule a standard service technician to come out. That technician and his supervisor are the ones who make the decision to "escalate the problem to network" (as in make a case and hand it off to network/line techs (maintenance techs) to deal with), and that's quite literally the last the customer ever hears of things (i.e. the assumption is made by all involved that network/line will resolve the issue). I speak from experience on this one. :-(

In my case, I was able to meet the network/line tech (maintenance tech) solely because of a Comcast employee on the official Comcast Forums (who shall remain anonymous per their request) "putting in a good word" for me behind-the-scenes + reaching out to someone at my local repair office (in Menlo Park) to look at the case. It was total chance that I actually *met* the guy -- I happened to be looking out my window the next day and saw a Comcast truck (with bucket) outside, where the driver got out and wandered around near our property looking up at utility poles. I went out and talked to him, asked him if he was handling my CR #, and he was. That's the guy, by the way, who I mentioned above (re: went to head-end, reproduced issue with 747MHz and higher, determined issue was same as what was seen in San Carlos).

If I call 800-COMCAST, all the CSRs are going to do is open up a new CR/case, link it/tie it to the old ones, and schedule to have a service technician come out. I've been down this road 3 times already, and all it does is waste service technicians' time since they can't solve the problem.
--
Making life hard for others since 1977.
I speak for myself and not my employer/affiliates of my employer.


koitsu
Premium,MVM
join:2002-07-16
Mountain View, CA
kudos:23
reply to HeadendJoe
Thanks, HeadendJoe, and JoelC707 See Profile (hi dude ).

As surprising as it might sound, I actually understand most of the terminology you've used, sans two terms: MER and NSG. I know what QAMs are, and I know what BER is (bit error rate; from my experience with DS1/DS3/OC3/OC12 and SONET), but the other two are new to me.

I put in a call to the "general manager" who I'd spoke to in the past (about service technicians). I think I'm going to let things sit until Wednesday.

If I don't get a call back from him by then, I'm going to try an alternate approach -- I do have a contact at Comcast who handles the PR and IP networking side of things, and I have a good relationship with that person. Possibly they can get me in touch with someone who can drive this.

Otherwise if that goes no where, I'll give my LFA a call and approach it from that angle.

I guess on the positive side, there's lots of hard data/evidence that I can provide, and there is a part of me (the engineer part ) that's happy that Comcast was able to confirm existence of the issue. Sometimes tracking down a problem is the hardest part. In this case though it seems to be getting it fixed that's a pain.

Will let folks know what transpires.
--
Making life hard for others since 1977.
I speak for myself and not my employer/affiliates of my employer.


HeadendJoe

@comcast.net
This is a NSG »harmonicinc.com/product/nsg-9000-6g

Essentially its an edgeQam that receives optical info and generates the info into RF QAM channels. So how Comcast works is that their CMTS routers are uBR10012 Cisco routers. The Downstream info (signal from the headend device to the node) leaves the router via fiber to the Harmonic NSG. The NSG outputs the info into multiple RF QAMs. Those QAMs eventually reach a transmitter where its converted back to optical, sent to the node, and then converted back to RF. Comcast also uses NSGs to convert VOD optical streams to RF QAMs.

Just a few definitions for you. MER (Modulation Error Rate) is the digital equivalent to SNR, which is the baseband measurement equivalent to Carrier to Noise. MER measures the ratio of error power to average power in an ideal QAM signal. MER measures the difference in quality between the transmitted modulation of a digital signal and the received modulation. Carrier to noise ratio is the measurement of the distance between a modulated RF carrier and the inherent noise floor. You can find a little more detail about these on Wikipedia.

Keep us updated for sure, hopefully it will get fixed. If you end up calling the FCC or your LFA, make sure you ask about Comcast's POP (proof of performance) testing. I believe by law the public has the right to review the outcome of those tests. They do the tests twice a year. May be worth glancing over if you're interested in where they found leaks in the plant during the test.