232 replies to this topic

[System Tech Senior]

Where you getting internal chip loss at?? Your return level out the tap is going to be determined by 2 things... 1. The value of the tap. 2. The pad that's in the LE..

[Thunderstruck]

The return output pad size is determined by the total return loss; cable loss, return insertion loss on passives etc. to ensure unity gain on the return path from active to next upstream active or "0" gain. If you trace the return path from the combined output (the forward output diplexer of an active) back thru the return you will hit the return amp chip(ours are 12dB) before the return output pad which again is used to ensure "0" gain to the next active upstream. Therefore if all is properly balanced upstream your Tx at an LE for example would be the amp chip plus the test point of LE/ or whatever Tap size. Amps have internal coupling/ splitters etc which factor differently but still the chip is counted. BTW you only subtract the chip value if determining Telemetry inversely from your injection level, otherwise you do add it to TP or Tap size if it's simply an LE/no other internal splits or combining etc. That's just how we does it. Maybe my english not so good sometime!!

Edited by Thunderstruck, 07 October 2010 - 08:43 PM.

[welder1994]

Got anything else Jonathan???

[whisper]

[wvandrie]

#45
What are you talking about You have a tap that will adjust the return aside from the foward???

Post a picture
olo131

Mayby I missed the info about these taps. (in that long topic).

But I noticed this recent contribution/forum:
http://www.line-man....__fromsearch__1

"Google search"

http://www.cisco.com...ecd806c7a31.pdf

http://www.cisco.com...091/7022397.pdf

73 Willy.

[bulldogmoe]

what is DOC 3.0???

lmao i kid i kid, we are still 1.1 here. we offer 7dn .05 up lmao
but some of our modems are wide open and we can get about 20-25mg dn 2-3up

[Capm]

You let your modems run wide open on a 1.1 system?

[jetsetwily]

http://www.speedtest.../2170450467.png


My (test) modem at home :) that is one of advantage when you are employed in cable company.


Docsis 3.0

"KOPERNIKUS" Cable Company, Serbia

We are offering speed from 3/0,5 Mbit/s to 50/2 Mbit/s. Four channel bonding in downstream and two (on some place four) channel bonding in upstream. In this year, we are gonna bond everywhere four channel in upstream.

But here, in Serbia  we are using Eurodocsis an that give us a lot of free space in return path (5-65 Mhz) in comparation with Docsis (5-42)...

Edited by jetsetwily, 10 September 2012 - 02:07 AM.

[Capm]

I can hit 275 down/ 40-50up on my modem here when I want to (8x2, package set to 320/120), but I find the wide open seem to lag a bit in online games, so I usually have mine set to our 50/10 package (I never use all that anyway), the config probably needs tweaked, but then, I don't expect we'll be selling that 300meg speed anytime soon.

Because of the way D3 works, you have to run the test a few times to force the modem to open up a bit.


Also, I might note, this stems from my problem with my Trilithic meter: If you're running a Cisco CMTS, and you have 8-channel bonding in place - 4-channel modems will not bond at all. So far, every 4-channel modem I've encountered has failed to bond. Its a problem with the CMTS software it seems. (sending incorrect rcp messages) If I set the CMTS wideband interface back to 4, the 4-channel modem locks right on. So, needless to say, we're only buying 8x4 modems here.

Arris did actually have a workaround for this in their firmware, but it seems motorola and hitron (makers of the trilithic modems) have not clued into this - afaik at this time. If CISCO would fix their CMTS software, that would be the more correct thing to happen, but has anyone tried talking to cisco lately? Theres no way to get to anyone with brains. (or it seems very difficult, anyway)

Edited by Capm, 10 September 2012 - 07:39 PM.

[jetsetwily]

Capm, thanks for info about 8 channel bonding and problem with 4+4 modems. We are using CISCO, and will keep that in mind.

[wvandrie]

Hi,
about subject #45 #145
Some more interesting info:
http://www.ecamgroup.com/Antronix E-Option Tech Document.pdf
http://www.motorola.....pdf?pLibItem=1

[olo131]

Nice share Willy. Keep them coming!!!!

[bulldogmoe]

i were just bought out by WOW and we had an engineer down here to look at our system to do the upgrades from doc1 to doc 3 and he told us the a C4 in michigan has over 22.000 modems on it!! were were like WTF!!!!! we cant even handle 5000 on ours
this is just the difference between doc1 and doc 3

[olo131]

You guys really need some good support. Glad to hear you are catching up with the rest of the world....

[bulldogmoe]

LOL yea how many years are we behind?

[olo131]

I don't think you lable in years you lable it in decades..... lol

[motorola870]

Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 1 783000000 Hz -4.4 dBmV 38.0 dB 30 0
2 Locked QAM256 2 789000000 Hz -4.7 dBmV 37.8 dB 94 0
3 Locked QAM256 3 795000000 Hz -5.2 dBmV 37.1 dB 119 0
4 Locked QAM256 4 801000000 Hz -5.4 dBmV 37.4 dB 251 0
5 Locked QAM256 5 807000000 Hz -6.2 dBmV 36.6 dB 552 0
6 Locked QAM256 6 813000000 Hz -6.0 dBmV 37.1 dB 372 2
7 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0
8 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0

Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked TDMA and ATDMA 10 2560 Ksym/sec 33000000 Hz 32.2 dBmV
2 Locked TDMA and ATDMA 9 2560 Ksym/sec 36500000 Hz 32.2 dBmV
3 Locked TDMA and ATDMA 11 2560 Ksym/sec 29500000 Hz 32.2 dBmV
4 Locked TDMA and ATDMA 12 2560 Ksym/sec 24500000 Hz 32.2 dBmV

what does everyone think besides the upstream power level?

rebooted modem on thursday evening and bam upstream bonding!

Edited by motorola870, 23 September 2012 - 04:39 PM.

[Capm]

Why the heck are they bonding such small channels? Its a waste of card space.

[motorola870]

Why the heck are they bonding such small channels? Its a waste of card space.

well I would assume because they are still trying to clean the plant up and also they had 4 upstreams for along time that were 3.2MHz with with QAM16/QAM64 mixed mode on them and they just bonded them to give the modem about 61Mbps to play with for a upstream speed of 5Mbps on the 30/5 and 50/5 tiers. I am betting they might raise the tiers to 30/10 and 50/25 but that is only rumored right now for TWC in markets with competition from fiber optic providers.

[olo131]

Just read that Cable labs are going to show off Docsis 3.1 at the Cable Expo in Orlando, Fl in November. They are calling it Docsis NG

Read this: http://www.multichan...ocsis-31/139611