I am having difficulty with my cable provider (comcast). Through the
cable box, a number of channels exhibit tiling, audio dropouts, or are
completely black. When I view these same channels directly on my
television (to the limit of its 99 channel tuner) they come in, albeit a
bit fuzzy. In addition to this, my internet speed rarely approaches the
paid for 8 meg, typically it's 5 meg or less. I'm wondering if this is
a signal level issue. I have a 60 mhz oscilloscope. Can I use this to
directly measure the signal at the cable outlet, and if so, what levels
should I see? Comcast has been less than stellar in its response to
these troubles, maybe if I can measure the signal levels I can at least
determine if the problem is a low signal to the house, or originates in
the distribution (cables, splitters, associated connections) internal to
the house.

TIA

Dan

Dan wrote:

I am having difficulty with my cable provider (comcast). Through the
cable box, a number of channels exhibit tiling, audio dropouts, or are
completely black. When I view these same channels directly on my
television (to the limit of its 99 channel tuner) they come in, albeit a
bit fuzzy. In addition to this, my internet speed rarely approaches the
paid for 8 meg, typically it's 5 meg or less. I'm wondering if this is
a signal level issue. I have a 60 mhz oscilloscope. Can I use this to
directly measure the signal at the cable outlet, and if so, what levels
should I see? Comcast has been less than stellar in its response to
these troubles, maybe if I can measure the signal levels I can at least
determine if the problem is a low signal to the house, or originates in
the distribution (cables, splitters, associated connections) internal to
the house.

TIA

Dan
check your splitters and all connections.


--
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

Dan -

This may or may not be relevant to your situation - I can't tell without
more info.

If you have high speed cable Internet (which it sounds like you do),
your cable modem measures signal strength, and you MAY be able to read
the actual measurements. For example, I have a Motorola Surfboard
modem, and whoever is out there at http://192.168.100.1/ will tell me
the signal levels at the modem, both uplink and downlink.

You can also go to BroadbandReports.com and run some error-rate tests.
These don't tell you the signal level directly, but a high error rate
can be very indicative of low signal levels. It is quite sesnitive,
right around the threshold level.

In my neighborhood, Cox cable gives me very good service, but they
really don't want to muck with the neighborhood-wide signal levels. I
understand why - there is a delicate balancing act between signal levels
and interference/distortion. If they crank up the Internet signal, it
produces interference in some of the cable TV channels. If they crank
up the cable TV channels, it produces interference in other channels.
Etc etc. Last time I called the Cox tech out, he agreed that the
incoming Interent level was too low at my location, and the solution was
to install a bi-directional amplifier right at the service entrance to
my house. This boosted the incoming Internet signal (but not the TV
channels) coming into my house. He set the amplifier to simply "bypass"
on the outgoing Internet signal. The neighborhood is happy, since
nothing happened out there. I am happy, since 6 dB more downlink signal
solved all my problems. Good solution!

Bill
~~~~~~~~~~~~~~~~~~~~


Dan wrote:

I am having difficulty with my cable provider (comcast). Through the
cable box, a number of channels exhibit tiling, audio dropouts, or are
completely black. When I view these same channels directly on my
television (to the limit of its 99 channel tuner) they come in, albeit a
bit fuzzy. In addition to this, my internet speed rarely approaches the
paid for 8 meg, typically it's 5 meg or less. I'm wondering if this is
a signal level issue. I have a 60 mhz oscilloscope. Can I use this to
directly measure the signal at the cable outlet, and if so, what levels
should I see? Comcast has been less than stellar in its response to
these troubles, maybe if I can measure the signal levels I can at least
determine if the problem is a low signal to the house, or originates in
the distribution (cables, splitters, associated connections) internal to
the house.

TIA

Dan

Bill writes good stuff. I'll just add that Comcast is very responsive to
the these issues and you should first try their technical support. Has
always worked for me and at no extra charge.

"Charles Schuler" wrote in message
. ..

Bill writes good stuff. I'll just add that Comcast is very responsive to
the these issues and you should first try their technical support. Has
always worked for me and at no extra charge.

By the way, I always request broadband technical support ... maybe that's
the difference.

"Charles Schuler" wrote in message
. ..

Bill writes good stuff. I'll just add that Comcast is very responsive to the
these issues and you should first try their technical support. Has always
worked for me and at no extra charge.


I agree. When I first got Comcast internet service, I had intermittent
service... slow login, sometimes unable to login, disconnects, etc. I called
Comcast and the tech they sent out fixed the problem on the first visit.
The original installer had run an extension to my computer from the back of my
main TV, where the cable was split to the rest of the house. The run from the
pole to my TV set is probably 175 - 200 feet when all the turns and bends are
accounted for. The tech looked at the signal levels, put a splitter in the line
at a point closest to my computer, and ran a separate line to my computer. He
said that increased the signal at my computer by about 3db. Haven't had a
problem since (except for when hurricanes knocked it out for over 2 weeks).
In retrospect, I probably need to replace all of the RG59 in my house.. it's
about 25 yrs old by now {:)

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Never take a laxative and a sleeping pill at the same time!!

Bill Jeffrey wrote:
Dan -

This may or may not be relevant to your situation - I can't tell without
more info.

If you have high speed cable Internet (which it sounds like you do),
your cable modem measures signal strength, and you MAY be able to read
the actual measurements. For example, I have a Motorola Surfboard
modem, and whoever is out there at http://192.168.100.1/ will tell me
the signal levels at the modem, both uplink and downlink.

You can also go to BroadbandReports.com and run some error-rate tests.
These don't tell you the signal level directly, but a high error rate
can be very indicative of low signal levels. It is quite sesnitive,
right around the threshold level.


Bill et al- thanks for the replies and Bill especially for the very
useful site referral, I'd never seen that one before. I do have a
Motorola modem (SB5101). The downstream measurements are 711 mhz (so
much for the 60 meg scope ;-/ ), SN ratio of 34.9 dB & power level of
-6.7 dBmV. Upstream is 23 mhz, 36.5 dBmV. If you can give me any
insights into the implications of these numbers, I'd appreciate it.
Also, what are they referring to on the page under "LOGS"? I see they
go back a month, are these stored in the modem? There are quite a few
entries reading "SYNC Timing Synchronization failure" of various types,
is this a problem?

As to calling comcast, I have repeatedly, they've sent out 3 guys, the
first 2 essentially did nothing, the last "jerry rigged" (to use his
term) the connector at the box end, saying the buried cable was of a
type they no longer support, and that most "techs" don't know how to do
this. This was 2 weeks after the initially "installation", despite
talking to several supervisors & an individual at their engineering
department & asking them to at least run a temporary line until the
repair could be effected, since I need the Internet to work from home.
I was told in a phone message from engineering that though I had NO
service, a temporary line "is not required". I don't doubt they may be
more responsive in areas where there are alternatives to their service,
that's limited here, especially for true high speed Internet (6-8 meg,
as opposed to .7-1.5 meg DSL), and in my experience their customer
service has sucked. On my most recent contact, I told a "supervisor" if
something wasn't done once and for all I'd have no choice but to cancel
my account. Without skipping a beat, she replied "would you like me to
go ahead and put that cancellation through now?" What an attitude.
Finally she said she'd "make a few calls & get back to me". That was
about 10 days ago, during most of which time I was on a business trip,
and I've heard nothing. I can't wait until there IS an alternatve to
the *******s. My previous cable company in another state was
Wideopenwest, I nver had a problem with them, though I'm sure there are
those with a different experience. Anyway, after replacing a wall jack
yesterday & cleaning up all internal connections involved the tv portion
is satisfactory (for the moment, knock on wood) but Internet speed (I do
use BroadbandReports.com) is still typically 60% of what it should be.

Thanks again all for the helpful replies.

Dan

Just for reference, here are my numbers for a SBV5120:

Downstream
Frequency: 603 MHz
S/N: 36 dB
Power Level: 5 dBmV

Upstream
Frequency: 33.024 mHz
Power Level: 30 dBmV

--
Tony Marsillo
Nutmeg Repair
-----------------------------------------------------------------
"Dan" wrote in message
...
Bill Jeffrey wrote:
Dan -

This may or may not be relevant to your situation - I can't tell without
more info.

If you have high speed cable Internet (which it sounds like you do), your
cable modem measures signal strength, and you MAY be able to read the
actual measurements. For example, I have a Motorola Surfboard modem, and
whoever is out there at http://192.168.100.1/ will tell me the signal
levels at the modem, both uplink and downlink.

You can also go to BroadbandReports.com and run some error-rate tests.
These don't tell you the signal level directly, but a high error rate can
be very indicative of low signal levels. It is quite sesnitive, right
around the threshold level.


Bill et al- thanks for the replies and Bill especially for the very useful
site referral, I'd never seen that one before. I do have a Motorola modem
(SB5101). The downstream measurements are 711 mhz (so much for the 60 meg
scope ;-/ ), SN ratio of 34.9 dB & power level of -6.7 dBmV. Upstream is
23 mhz, 36.5 dBmV. If you can give me any insights into the implications
of these numbers, I'd appreciate it. Also, what are they referring to on
the page under "LOGS"? I see they go back a month, are these stored in
the modem? There are quite a few entries reading "SYNC Timing
Synchronization failure" of various types, is this a problem?

As to calling comcast, I have repeatedly, they've sent out 3 guys, the
first 2 essentially did nothing, the last "jerry rigged" (to use his term)
the connector at the box end, saying the buried cable was of a type they
no longer support, and that most "techs" don't know how to do this. This
was 2 weeks after the initially "installation", despite talking to several
supervisors & an individual at their engineering department & asking them
to at least run a temporary line until the repair could be effected, since
I need the Internet to work from home. I was told in a phone message from
engineering that though I had NO service, a temporary line "is not
required". I don't doubt they may be more responsive in areas where there
are alternatives to their service, that's limited here, especially for
true high speed Internet (6-8 meg, as opposed to .7-1.5 meg DSL), and in
my experience their customer service has sucked. On my most recent
contact, I told a "supervisor" if something wasn't done once and for all
I'd have no choice but to cancel my account. Without skipping a beat, she
replied "would you like me to go ahead and put that cancellation through
now?" What an attitude. Finally she said she'd "make a few calls & get
back to me". That was about 10 days ago, during most of which time I was
on a business trip, and I've heard nothing. I can't wait until there IS
an alternatve to the *******s. My previous cable company in another state
was Wideopenwest, I nver had a problem with them, though I'm sure there
are those with a different experience. Anyway, after replacing a wall
jack yesterday & cleaning up all internal connections involved the tv
portion is satisfactory (for the moment, knock on wood) but Internet speed
(I do use BroadbandReports.com) is still typically 60% of what it should
be.

Thanks again all for the helpful replies.

Dan

Tony Marsillo wrote:
Just for reference, here are my numbers for a SBV5120:

Downstream
Frequency: 603 MHz
S/N: 36 dB
Power Level: 5 dBmV

Upstream
Frequency: 33.024 mHz
Power Level: 30 dBmV

Thanks Tony, so your power level is 5, not NEGATIVE 5? (mine was -6.7)

Dan

Dan wrote:

Tony Marsillo wrote:

Just for reference, here are my numbers for a SBV5120:

Downstream
Frequency: 603 MHz
S/N: 36 dB
Power Level: 5 dBmV

Upstream
Frequency: 33.024 mHz
Power Level: 30 dBmV

Thanks Tony, so your power level is 5, not NEGATIVE 5? (mine was -6.7)

Dan
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
And here are my numbers
Down
579 MHz
SNR = 34
Power = -5
Up
19.599667 MHz
Power 44 dBmV

I think the power level of -5 is OK. I seem to remember reading
somewhere that it should be above -10, and sure enough when mine was -10
was when I was ahving the trouble. The amp I spoke about is what raised
it to -5, and now I have no trouble.

Did you dig down into BroadbandReports.com? They keep changing the page
layout on the opening page, and it looks like they have reached a new
high in uselessness. But if you go down to
www.broadbandreports.com/tests and start looking around, it is a lot
more useful. In particular, I came across an entire section on Cable
Modem and Wiring Issues, and it touches on signal strength issues.

There is an entire saection on Comcast, one on Cox, one on Adelphia, etc.

Good luck.

Bill

Bill et al- thanks for the replies and Bill especially for the very
useful site referral, I'd never seen that one before. I do have a
Motorola modem (SB5101). The downstream measurements are 711 mhz (so much
for the 60 meg scope ;-/ ), SN ratio of 34.9 dB & power level of -6.7
dBmV. Upstream is 23 mhz, 36.5 dBmV. If you can give me any insights
into the implications of these numbers, I'd appreciate it.

http://www.speedguide.net/read_articles.php?id=1197



Sorry that you are having trouble with Comcast ... that is not typical ... I
wonder what is different in your case? I'd suggest going to the top with a
letter or two. I find that letters have much more impact than emails and
phone calls.

Dan,
Yes that is +5 dBmV

--
Tony Marsillo
Nutmeg Repair
-----------------------------------------------------------------
"Dan" wrote in message
. ..
Tony Marsillo wrote:
Just for reference, here are my numbers for a SBV5120:

Downstream
Frequency: 603 MHz
S/N: 36 dB
Power Level: 5 dBmV

Upstream
Frequency: 33.024 mHz
Power Level: 30 dBmV

Thanks Tony, so your power level is 5, not NEGATIVE 5? (mine was -6.7)

Dan