adambpsu
Adam
Premium
join:2003-02-08
Harrisburg, PA
1 edit | reply to Exceles
Re: Terayon TJ210 question
Good call Mac. I guess I wasn't thinking, as I have always wondered what exactly determined the lower limit in the DOCSIS standard. Thanks for correcting me on that.  |
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MacLeech
The one and only
Premium
join:2001-07-14
SoCal
2 edits | reply to adambpsu
said by adambpsu  :
The lower the better. He should be fine.
Wrong, if a signal level is too low it starts getting into the noise, in this case you would see this as a lower SNR on the upstream. Too low of an SNR and the receiver can't differentiate the signal from the noise.
For upstream you want the level as high as possible without getting into the region of signal variations due to weather or minor plant cable changes that would push the modem over a transmit level of 58 (or 55 depending on QAM used) dbmv. 40 - 50 dbmv is nice.
Also lower upstream levels mean the cable system is more vulnerable to ingress and noise coming from subscribers drops (since its not attenuated as much as it should be). This causes even more issues to modems with low transmit levels because then they have to compete with that noise as well.
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Adelphia - Is it working now? |
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adambpsu
Adam
Premium
join:2003-02-08
Harrisburg, PA
2 edits | reply to Stiv2k
said by Stiv2k :
well your SNR is in range, that's good, but your downstream signal is quite high, although I believe DOCSIS supports up to 15 dB...
I would agree. However, if he is not having any problems, then I would just leave it as it is. I know, like you said, that it seems high, but he should be okay.
The lower the better. He should be fine.
All in all though, not the best signals I have ever seen. Maybe you can even get those amended even more if you have troubles?
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Adam Number Two...
"They have the internet on computers now?" |
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Stiv2k
Rm -Rf As Root
join:2002-07-22
Orlando, FL
| reply to Exceles
well your SNR is in range, that's good, but your downstream signal is quite high, although I believe DOCSIS supports up to 15 dB...
Your upstream signal is way too low, you want that to get up in the 40's :/
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- Steve Bularca |
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Exceles
join:2002-10-05
Fredericksburg, VA
| reply to Exceles
Ok a followup. The tech came out monday and fixed the signal issue by locating the line the modem was on and placing it on the first split.
Even since then I've had no problems.
All is well.
Thanks for all the help
New levels:
Tx Power 22.2 dBmV
Rx Power 13.9 dBmV
Downstream SNR 32.2 dB
Tx Frequency 34000000 Hz
Rx Frequency 573000000 Hz |
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Exceles
join:2002-10-05
Fredericksburg, VA | reply to Exceles
Not sure about the freq., but I can easily find out when daylight comes tomorrow (along with 4+ degrees of warmth too!). |
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adambpsu
Adam
Premium
join:2003-02-08
Harrisburg, PA
| reply to MacLeech
said by MacLeech :
The highest frequency the vast majority of cable systems might use at this time is about 860 Mhz. So it doesn't matter if the splitter is rated to 900Mhz or 1000 Mhz as long as its above the highest frequency used in your local system for services you're recieving.
Ahhh. That makes sense. I never thought about how high the frequency actually. Since I never knew differently, I just always assumed since the splitter was rated for 1000 MHz, that is how high a frequency the system was using. Thanks Mac.
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Adam...Uh, someone broke the internet again! |
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MacLeech
The one and only
Premium
join:2001-07-14
SoCal
| reply to cheech4cs
said by cheech4cs :
Also what are the Mhz on the splitters?? Correct me if I'm wrong but you want them to rate at least 1000Mhz. The standard ones/OLD ones are like 900Mhz.
The highest frequency the vast majority of cable systems might use at this time is about 860 Mhz. So it doesn't matter if the splitter is rated to 900Mhz or 1000 Mhz as long as its above the highest frequency used in your local system for services you're recieving.
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Adelphia - Is it working now? |
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adambpsu
Adam
Premium
join:2003-02-08
Harrisburg, PA
| reply to cheech4cs
said by cheech4cs :
Also what are the Mhz on the splitters?? Correct me if I'm wrong but you want them to rate at least 1000Mhz. The standard ones/OLD ones are like 900Mhz. I was told that by a tech when the first came out. I ponder that thought because isn't the service on a loop?? Just a thought and what I've been told.
Yes, you need a splitter ranging to the 1000 MHz range. I think that they are rated 5-1000 MHz. I could be wrong too, but I thought that I remembered this correctly.
What do you mean by a "loop?"
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Adam...Uh, someone broke the internet again! |
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cheech4cs
join:2003-10-24
Hollis Center, ME
| reply to Stiv2k
Also what are the Mhz on the splitters?? Correct me if I'm wrong but you want them to rate at least 1000Mhz. The standard ones/OLD ones are like 900Mhz. I was told that by a tech when the first came out. I ponder that thought because isn't the service on a loop?? Just a thought and what I've been told. |
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Stiv2k
Rm -Rf As Root
join:2002-07-22
Orlando, FL | reply to Coolbrz
Yeah the signal is probably good coming off the tap, but it just gets crapified going through all the splits
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- Steve Bularca |
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Coolbrz
join:2002-12-16
Port Allegany, PA
| reply to Stiv2k
said by Stiv2k :
ahem...20dB Rx and 2dB Tx is WAY out of the appropriate limits...and he already said he has a problem getting an IP, maybe because his singal is so bad that he can't talk to the DHCP server? sounds like a problem to me.
A few other tests showed different, which is why I said what I did. And in his post,
quote:
First I had the router connected to it, but it wouldnt get an IP.
Then I connected the laptop to it, still no IP.
Finally I connected it to the desktop, and it pulls an IP in the range of 67.*.*.* something.
I get it working, then switch it to the router after I made the post and it seems to be working ok now...
I am just trying to narrow down the issue here, speed tests look good, and I too was wondering how he was maintaining a connection with the signals that he posted. I am curious as to how much it is dropping the connection. Let us know what the tech says. |
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Exceles
join:2002-10-05
Fredericksburg, VA | reply to Exceles
Tech is definitely coming out on Monday.
I'll see what I can do to get the modem on the first split.
if push comes to shove, I'll go outside and by trial and error get the modem line on the first split. |
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Stiv2k
Rm -Rf As Root
join:2002-07-22
Orlando, FL
| reply to Coolbrz
ahem...20dB Rx and 2dB Tx is WAY out of the appropriate limits...and he already said he has a problem getting an IP, maybe because his singal is so bad that he can't talk to the DHCP server? sounds like a problem to me.
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- Steve Bularca |
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Coolbrz
join:2002-12-16
Port Allegany, PA
| reply to Exceles
I would check a few more times on those signal levels, maybe even a call in to tech support. If all seems well right now and it runs well overnight and tomorrow then you may not have an issue, if the tech still comes to the house, you may be charged for the service call if he finds nothing wrong. |
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Stiv2k
Rm -Rf As Root
join:2002-07-22
Orlando, FL
| reply to Exceles
WOW...those are the worst signal levels I have ever seen! 
You need to have your cable modem come off the first split so it doesn't lose as much signal. All splitters are made to lose a certain amount of singal on them, they are marked "-3dB" on them which means you lose 3dB of signal going through that splitter.
Considering your modem goes through at least 5 splits of approximately 3-5 dB signal loss, I'm not suprised you have a downstream signal of -20dB! I also can't believe your modem can sync under those conditions...lol
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- Steve Bularca |
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Exceles
join:2002-10-05
Fredericksburg, VA
| reply to Exceles
First I had the router connected to it, but it wouldnt get an IP.
Then I connected the laptop to it, still no IP.
Finally I connected it to the desktop, and it pulls an IP in the range of 67.*.*.* something.
I get it working, then switch it to the router after I made the post and it seems to be working ok now...
Speeds are up and alot better then with that TJ210. Either that modem was tired of dealing with the crappy signal, or it had just been through its service life :\
The cable is split outside about....atleast 5 times with 2 and 3-way splitters to give the house 9 outlets on 3 levels(2 in the basement, 4 on the main level, and 3 upstairs), only 3 of which are used (2 TVs and the modem, modem on main level). The house was wired this way when my parents purchased it.
I might move the modem back to the basement if I can convince my mother to let me run Cat5e all over the place so I can have the modem in the basement, with the WAN link from it to the wireless router on the main level. |
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Coolbrz
join:2002-12-16
Port Allegany, PA | reply to Exceles
When you say quote:
Just having trouble getting and keeping an IP on it
Do you mean the modem loses sync, lights start flashing or are you losing the IP on the computer? |
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wolfenstein9
join:2003-12-03
Buffalo, NY | reply to Exceles
if those are indeed your signals measurements, then you really need a tech out there. In fact, i have never seen such horrible signal, how in the world did your modem sync up. your lines have to be balanced. |
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Coolbrz
join:2002-12-16
Port Allegany, PA | reply to Exceles
»Adelphia High Speed Internet »FAQ: Acceptable cable modem signal levels.
Your signals do not look so good. |
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