bigjer
Premium
join:2002-03-26
| reply to keo eke
Re: Disgusted with cable 1st few hours
Hey, Thanks to the many experts on this forum I have achived really good speeds.
Upload-130kb/s
Download-3mb/s
1) I can't complain about that. Mostly what I did was reboot the modem ( shut down overnight ).
2) I went to speedguide.com as you people recommended and downloaded a registry tweak for concurrent downloads and that was it.
Ping tests (PCPitstop) were good, between 14ms & 100ms mostly. With the exception of the last site on the test. Australia I think. That one was over 200 ms.
My computer runs great, has a snap to it it didn't have before.I thank you for your sharing your knowledge and experience with me. Have a good night. |
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keo eke
Razorback
Premium
join:2002-11-20
Georgia
| reply to ThreeD
According to DOCSIS specs modems should WORK from -15 to +15 but it says nothing about "quite nicely". I would say that having an upstream in the mid 30's and low 30's is unusual at least by design. Your modem will find the downstream and then will start broadcasting from +8 to +58dbmv to the headend until the headend says "I see you" it is at that point that the headend can adjust levels at the modem but only by 1 dbmv or so. Your SNR of 32.1 is OK, Modems should work from about 24 to 36db of SNR with no problem but it is better to be on the upper end than the lower end and you can add a db or two each way.
Once your signal gets above 54 or 55 dbmv other factors(distortions) come into play but up to that point your CNR(carrier to noise) and SNR(signal to noise) will continue to improve but once above that threshold the other distortions rapidly cancel out the affects of higher signal level. The same applies with to low of a signal, CNR and SNR will not be high enough away from the noise floor for good digital(modem) operation. |
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ThreeD
join:2001-05-19
Southern Cal
clubs:
| reply to keo eke
said by keo eke  :
You are correct, the headend does tell the modem if it should transmit higher or lower but it can only adjust the signal level about +1 or -1 dbmv at 1/4 dbmv intervals.
Good information. I did not know about the change limitations in xmit strength. I guess I need to go back and read that chapter again.:)
I have had the same levels, give or take a .5dBmv for about 5 months now and also the receive signal only varies about .5dBmv. No problems with the connection in that time and it is on 24/7. Prior to that I had a different modem with similar levels and results. The one thing that you mentioned that interests me is that with a higher xmit level, my SNR would potentially be better. Had not thought about that and the SNR is a bit low at 32.1db. I would prefer to see better on that, although as you also said, if it is not broken, don't fix it. |
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keo eke
Razorback
Premium
join:2002-11-20
Georgia
| reply to ThreeD
You are correct, the headend does tell the modem if it should transmit higher or lower but it can only adjust the signal level about +1 or -1 dbmv at 1/4 dbmv intervals. The modem will transmit at different levels until the headend tells the modem "I see you". The SNR will be better the higher the modem transmits up to about 55dbmv, hence may statement started with the word MOST, if your system is quiet and there are not tons of modems, digital boxes and ingress getting back to the headend than 33dbmv may work fine for you but if you start having trouble then I would look at why you are only transmitting at 33db.
My modem never goes offline and it has -12dbmv hitting it going through 2 2-way's and 1 3-way splitter, but if I had trouble than I would change the config back to the way Adelphia set it up but hey if it's not broke don't fix it. |
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ThreeD
join:2001-05-19
Southern Cal
clubs:
| reply to keo eke
said by keo eke :
Most modems need to transmit at least 40 dbmv and not more than 54 dbmv on the upstream side to be effective(yours is at 33).
Not to be argumentative, I am sure that some modems have trouble as you say with those signal levels, but - Most DOCSIS modems, according to DOCSIS spec. will operate quite nicely on a receive signal between -15 to +15 dBmv. On the upstream, it is not unusual to have a signal in the mid 30 dBmv range. My modem is currently xmitting at +32.7 dBmv and my receive signal is +5dBmv. The xmit is controlled by the head end equipment. It tells your modem what strength to xmit at so that the head end receives a good signal. In fact when the xmit signal goes into the 40's, I would start getting concerned about the return signal path have too much loss. YMMV.:) |
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keo eke
Razorback
Premium
join:2002-11-20
Georgia | reply to bigjer
hope that helps. |
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bigjer
Premium
join:2002-03-26 |  reply to keo eke
Thank you. |
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keo eke
Razorback
Premium
join:2002-11-20
Georgia | reply to bigjer
Well you could go over to the Adelphia forum and at the top of the page there are two good links to read through about cable modems. |
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bigjer
Premium
join:2002-03-26 | reply to keo eke
Good idea, I'm not to cable savvy. Thank you.
BTW, where can I get some specific info on all of this?
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WinMeDiml866rAdAware6ZoneAlarm 3NAV2002Comcast cableRCA DCM235 Modem |
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keo eke
Razorback
Premium
join:2002-11-20
Georgia
| reply to bigjer
No bigjer you need to call Comcast and have someone from the maint. dept. look at your line. Most modems need to transmit at least 40 dbmv and not more than 54 dbmv on the upstream side to be effective(yours is at 33). It is hard to say where your problem is, either in your home or on the Comcast main line. You could go out and get a 4-way splitter(rated from5-1000mghz) and put it between your modem and the wall jack where the cable comes into the room and get your levels to spec but not knowing how many outlets are in your house and how many splitters there are before the modem makes a big difference. I think you should call Comcast and swing over to the Comcast forum to see if anyone in your area has been having trouble. Keo |
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bigjer
Premium
join:2002-03-26 | reply to CableGuyNJ
CableGuyNJ, Can I do this stuff myself or is this to difficult and expensive? Also, where do I get instructions?
You're a great help, thank you.
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WinMeDiml866rAdAware6ZoneAlarm 3NAV2002Comcast cableRCA DCM235 Modem |
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CableGuyNJ
join:2003-01-25
USA
| reply to bigjer
no...he doesn't have good levels. Your downstream power (7.2dBmV) is too high. and your return/upstream (33dBmV) is too low. you need to either have a cable tech give you an attenuator pad of -6dB or move your cable outlet to a different splitter or splitter port.
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Have you smacked your contractor today? |
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Jeff7477
join:2003-01-08
Lincoln, NE | reply to bigjer
you have good levels |
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bigjer
Premium
join:2002-03-26
| reply to CableGuyNJ
CableGuyNJ, This is what I got when I clicked on the link you provided.
forward path
signal acquired @ 555.004
snr 35.9 db
received signal strength 7.2dbmv
micro-reflections 23dbc
modulation 64 qam
data service details
provisioned address-yes
provisioned time-yes
provisioned configuration-yes
registered-yes
bpi-disabled
return path
connection-acquired
frequency-22mhz
power level-33.0dbmv
channel id-20
modulation-qpsk
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WinMe
Diml866r
AdAware6
ZoneAlarm 3
NAV2002
Comcast cable
RCA DCM235 Modem
[text was edited by author 2003-02-15 21:20:08] |
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CableGuyNJ
join:2003-01-25
USA | reply to bigjer
for the RCA it is:
192.168.100.1/moreinfo.html
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Have you smacked your contractor today? |
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Jabbu
Premium
join:2002-03-06
 ·RoadRunner Cable
| reply to bigjer
said by bigjer :
dw2, This is my second try to post this same message. My os is Windows Millenium, which has run smooth and stable since day one.
An absolute miracle. |
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bigjer
Premium
join:2002-03-26 | reply to bigjer
Thanks, I will follow your instructions and post my results. |
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joe bauers
join:2002-04-16
Emmetsburg, IA
| reply to bigjer
Here are the steps to switch your IP address from an automatically assigned one to a static one, for accessing the internal diagnostics page for certain RCA cable modems (DCM 225, 235 and 245). This should work for Windows 95, 98 and ME. Note: you may want to print out this page as a reference.
1. Go to the network control panel (start, settings, control panel, then select the Network control panel).
2. In the network control panel, you will find a white box labeled "The following network components are installed:". Double click on "TCP/IP -> (model of your ethernet adapter)".
3. A window labeled TCP/IP properties should pop up, and the IP address settings should be visible. Click on the button for "Specify an IP address", and enter 192.168.100.10 in the IP address area, and 255.255.255.0 in the Subnet Mask area.
4. Click on the OK button on the bottom of this window, and the OK button at the bottom of the network control panel. You should now be prompted to restart the computer.
5. After the computer restarts, you should be able to access the diagnostics page.
To access the main diagnostics page for the RCA cable modems, go to: »192.168.100.1/moreinfo.html (signal levels). There is another diagnostics page with basic information at: »192.168.100.1/diagnostics.html.
To set everything back to normal, go thru steps 1 and 2, as shown above, but for step 3, click on the button for "Obtain an IP address automatically", and continue to step 4. |
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l33tn00b
L33tn00b
Premium
join:2001-04-03
Plano, TX | reply to bigjer
Try this website ... somewhat works
»www.speedguide.net
a famous site heh |
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bigjer
Premium
join:2002-03-26 | reply to bigjer
dw2, This is my second try to post this same message. My os is Windows Millenium, which has run smooth and stable since day one.
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WinMeDiml866rAdAware6ZoneAlarm 3NAV2002Comcast cableRCA DCM235 Modem |
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