I have a splitter in the line for analog local stations, now, and the
modem reports 7 dBmV "Downstream", and 49 dBmV on "Upstream".
Access.TimeWarner still reports the same speeds in the mid-1 Mbps
to low 3 Mbps, but speeds measured from SpeakEasy's Los Angeles
server measure from the high 3 Mbps to high 5 Mbps, depending on
the time of day and the alignment of passing meteors. Tracerts still
report intermittent timeouts - most of them occuring within the RR
network. I'd be trying DSL right now if it weren't for the one year
committment.

*TimDaniels*

"Ed Nielsen" wrote:

> If it were me, Tim, I would pad that down by another 6dB, bringing

> the downstream down to +3 and the transmit up to around +53dBmV.

> Only, I would have ALL of the padding at the splitter that feeds your

> cable modem. If it is a splitter, perhaps change that out for a directional

> coupler of comparable value. Many engineers like to see cable modems

> run out on the hot side. It helps it to be heard over any noise that

> might get on the drop. 53 is perfectly fine. DOCSIS specifies a high

> end of 58.

> Then again, if you have a DCT(digital cable box), the increase in signal

> level a DC would give it could cause it some grief. Might have to throw

> in a 3dB pad on the THRU leg of the DC.

> CIAO!

> Ed N.

> Timothy Daniels wrote:

>> The line technicians were by today, and they said the signal level

>> on the downstream side (coming into our property) was a bit high,

>> so they padded it down by 4-5 dB. Now the modem is reporting a

>> downstram signal level of 9 dBmV and an upstream signal level of

>> 47 dBmV. It had been 15-17 downstream and 50-52 upstream.

>> I asked the tech who adjusted our amp if those numbers meant

>> NEGATIVE dB, but he said no (which may still not mean anything).

>> The bottom line is that the speeds have increased a bit, but it's

>> not really obvious due to the high variance from test to test. Tracerts

>> are still showing timeouts, and InternetFrog.com is showing "Quality

>> of Service" levels ranging between 9% and 50%, i.e. high retransmission

>> rates, and the VOIP test indicates that there would be lots of dropouts

>> and pauses. I believe it's due to congestion in the RoadRunner network.

>> *TimDaniels*

Posted by Todd H. on December 22, 2006, 1:23 am

If you were Registered and logged in, you could reply and use other advanced thread options

> >groan> The RR news servers have been down for several days.

> I have a splitter in the line for analog local stations, now, and the

> modem reports 7 dBmV "Downstream", and 49 dBmV on "Upstream".

> Access.TimeWarner still reports the same speeds in the mid-1 Mbps

> to low 3 Mbps, but speeds measured from SpeakEasy's Los Angeles

> server measure from the high 3 Mbps to high 5 Mbps, depending on

> the time of day and the alignment of passing meteors. Tracerts still

> report intermittent timeouts - most of them occuring within the RR

> network. I'd be trying DSL right now if it weren't for the one year

> committment.

> *TimDaniels*

Hi Tim, I think that 49dB on teh transmit side is straining things.
Is this a traditional 2:1 splitter or is it a directional coupler?
Try eliminating the splitter for grins and re-running

ping -t www.yahoo.com

for a good long while to get a feel for your packetloss rate
before/after the elimination of the splitter. Traceroutes aren't a
great measure of packet loss.

If eliminating the splitter helps your situation, and if it's not a
directional coupler/directional tap they have in there for you, call
the cable company and get the tech's back out and nudge them in that
direction. They can slap a directional coupler in there in seconds
and it may give you another 2 or 3 dB of margin on the transmit side
and make your modem happier.

Best Regards,
--
Todd H.
http://www.toddh.net/

Posted by Timothy Daniels on December 22, 2006, 2:50 am

If you were Registered and logged in, you could reply and use other advanced thread options

"Todd H." wrote:

> "Timothy Daniels" writes:

>> I have a splitter in the line for analog local stations, now, and the

>> modem reports 7 dBmV "Downstream", and 49 dBmV on "Upstream".

>> Access.TimeWarner still reports the same speeds in the mid-1 Mbps

>> to low 3 Mbps, but speeds measured from SpeakEasy's Los Angeles

>> server measure from the high 3 Mbps to high 5 Mbps, depending on

>> the time of day and the alignment of passing meteors. Tracerts still

>> report intermittent timeouts - most of them occuring within the RR

>> network. I'd be trying DSL right now if it weren't for the one year

>> committment.

>> *TimDaniels*

> Hi Tim, I think that 49dB on teh transmit side is straining things.

> Is this a traditional 2:1 splitter or is it a directional coupler?

> Try eliminating the splitter for grins and re-running

> ping -t www.yahoo.com

> for a good long while to get a feel for your packetloss rate

> before/after the elimination of the splitter. Traceroutes aren't a

> great measure of packet loss.

> If eliminating the splitter helps your situation, and if it's not a

> directional coupler/directional tap they have in there for you, call

> the cable company and get the tech's back out and nudge them in that

> direction. They can slap a directional coupler in there in seconds

> and it may give you another 2 or 3 dB of margin on the transmit side

> and make your modem happier.

> Best Regards,

> --

> Todd H.

> http://www.toddh.net/

Without the 2:1 splitter, the downstream signal level rises to 10 dBmv
(from 9 dBmV) and the upstream signal level drops to 47 dBmV (from
49 dBmV). The tracerts show a quadrupling (or more) of timeouts with
the splitter removed. It seems that the lower transmit level hinders the
packets' survival rate, and that the splitter, in reducing the receive level,
causes the modem to drop its transmit level and thus increases the
timeout incidence. Is that right?

BTW, *I* put the splitter between the modem and the RR network
for analog cable TV reception of local stations. Whenever the techs
were here, the splitter had been replaced by a barrel connector
(don't ask). As far as TW is concerned, my only service from them
is RoadRunner. But no instruments measured levels within my condo
unit. The only measurements that they took directly were on the level
from the amp in the vault at the curb and on the output from the building's
amp that resulted from their padding down the signal coming from the
curb amp. The only measurements that they took specific to my modem
were the remote readings reported to them from by cell phone from the
central office. They said that it gave them more information than what
I got from the modem's webpage and, presumably, what they could learn
by tapping into the line between the wall outlet and my modem. So it's
strange that the timeouts are so much less frequent when I put my 2:1
splitter in the line - it is not what they thought the usual configuration was.

*TimDaniels*

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