I live in a townhouse. When I first moved in here 6.5 years ago I had
cable internet, but I got a much better deal on DSL so I dropped it
after a month or two even though Cable was faster. A couple of
weeks ago decided I'd try cable internet again. While waiting for a
new modem, they were able to get me online with an old 3Com "Shark
Fine" modem for a few days without problems before a new Motorola
Surfboard was sent to me. When using the old 3Com, the service was
good (no outages), but the top download speed was around 4.7mbs.

When I installed the new Surboard, the top speed was faster. However,
after the first day I discovered that there was an intermittent
problem of the modem losing the signal. What I'm finding funny, is
that when the Surfboard would lose the signal and go offline, the
3Com, if connected, would be able to get online according to the cable
company. I even tried connecting both the Surfboard and the 3Com to
a the same two-way splitter and only the 3Com would get a signal
during the outages. That led me to believe the problem was the
Surfboard. They set up an appointment to have a technician arrive. I
continued to use the Surfboard for a few days with at least 2
intermittent outages per day.

When the tech arrived, he measured the line signal and did a few
things to improve it, such as replacing an unnecessary 3-way splitter
with a two way, and replace a few bad connectors in the system, adding
a filter on one of the lines going into the bedroom which he said was
failing for noise that was likely coming from the TV, and adding a
filter to the little TV in the office which he said was generating
noise. He claimed his machine was still picking up "ingress" (noise)
from the two older approximately 23-year old original cables from when
the townhouse was originally built. While I agree that these two
cables are older and thinner than what is currently used, and
"ideally" would be good to replace, and they may be picking up some
noise if his machine is really telling the truth and calibrated
correctly, etc, but I wouldn't want to replace them unless as a last
resort, because they are snaked through walls. One of them goes from
basement-level to attic above 2nd story and the other from basement-
level in front of house to 1st story at rear of house. I'm not
allowed to have the cable company run wires outside the townhouse and
the cable company won't snake new wires for me internally, so I would
need to hire an electrician to do the work unless I wanted an ugly/
visible wiring job. I fear it would be expensive to have an
electrician install new CATV wires. How much would it generally be
expected to cost to replace these 2 main cables in my townhouse and is
there any risk of damaging anything from having the work done? (NOTE:
In addition, 2 cables going from the attic to 2nd story would likely
need replacement as well) Any idea would the total job should cost?

Anyway, I think the technician did improve the signal to the Surboard
even though he claims I should still replace the 2 older main cables.
There is still no explanation as to why the 3Com didn't have the
problem. Currently the Surfboard says the Downstream Power Level is 5
dBmV when previously it was zero. Currently the S/N ratio is 36 to
37 db, but I believe it said the same thing previously. No outage has
occurred since the technician left yesterday so I'm keeping my fingers
crossed. If I do still get these outages, then my plan is to move the
modem downstairs to an outlet in the kitchen which the technician said
is a good/newer line. If that doesn't make the outages go away, then
I would temporarily disconnect the 2 older lines from the system
altogether by removing them from the splitter in the garage. I would
temporarily lose the ability to watch some of the TVs in the house.
If I still get intermittant outages then I would know that the it is
utter BS that the older lines were the cause the outages. (I'll
reiterate that the 3com modem did not get any outages.) Only if
disconnecting the older 2 lines from the system is the only solution
to problem would I get involved with replacing them.

My opinion, until proven otherwise, is they just want to use the
"older cables" as an excuse to not look further into a problem.
(I'll reiterate that the 3Com wasn't getting any outages, and TV
signal looked fine during the outages) What I find disturbing is that
I was also told by the cable company technician that periodically they
go around and check noise levels at the pole or, or in my case green
boxes on the ground outside the buildings in my development.
Supposedly if they detect that the cable connected to my townhouse is
introducting too much noise into their system, they could just throw
on a filter at the box without even telling me and then I would
instantly lose internet as well as some functionalty to my TV
converter box. I would then have to schedule a tech call and if the
tech finds the filter, I would then be forced to replace or remove the
older lines from the system before they would unfilter my line
again. Is this a bunch of BS or would they really do that? It seems
to me the noise levels would have to be severe for them to do that,
right? Is he BSing me?

If it is true that the older cables are picking up some noise, then
where is the noise coming from? How long do indore CATV cables
last? Do they just wear out from sitting there in the house for a
certain time period? At one point, he connected his noise-measuring
device to one of the main lines from the end in the attic and said it
passed. When he connected the machine to the opposite end in the
garage he claimed it failed for ingress which is strange and makes me
wonder if the cable is really problematic.

Anyway, so far no outages since the tech was here. I'm hoping that he
improved the signal enough to solve the outage problem. I'm getting
up to around 7.5 mbs with this modem, which isn't ideal, but it is
more than double DSL speed so it's fine with me. If I still get
outages then I will take the steps mentioned previously before getting
involved with replacing the older cables. I'm just wondering if it is
BS that they would filter my cable line against my will just for
having older cables that happen to pick up some noise. What I find
hillarious is that DSL is able to work with thin telephone wiring that
I believe has no noise shielding in and of itself, and is the same age
as the older CATV cables, but the cable company is telling me that I
should replace the older CATV cables to ensure a reliable cable
internet service, and so that I don't eventually get a filter slapped
onto my cable line at the exterior box. Something seems fishy to me
about what I am being told! Yes two of the cable lines in my house or
older and less than ideal, but I'm not sure I'm buying that they
really NEED to be replaced. What would it cost to replace them?

J.

The problem could be standing waves. I don't think any FSM is accurate
enough to detect that. First of all the cable modem requires a
specific frequency, but it also requires the sidebands. In some cases
standing waves can cause complete eradication of 400,0001 Mhz yet
barely affect 400.0002 and 400.0000 Mhz. If this happens the signal
strength is fine bit there is so much distortion in the modulation
that the signal is near unusable.

Remember reorienting the antenna to get rid of ghosts in a TV picture
or distortion in an FM signal ? It is the same thing. Standing waves
are very much like multipath in their effects on signal quality. Some
old FM tuners actually had a scope built in to display multipath. The
optimum signal would display pretty much a flat line. Moving the
antenna would cause dips in the line, and that is what causes
distortion. Measuring signal strength just doesn't cut it.

He may have been blowing smoke about the TVs polluting the signal.
It's hard to believe the effect would be a big problem if they meet
FCC requirements on radiation. But then it's possible that he was just
attempting to improve the signal as much as possible. Hard to say. I
know people get alot of lip service when what they want is service,
this one is tough to call either way. Maybe he just did what he
could.

But FCC requirements say nothing about antenna input impedance, if
that is off it can cause the standing waves. I'm not sure if a filter
would take care of that completely. It seems it should but I know
better, things do not always work as they are supposed to.

If you are talking a "thinner" cable than what is used tody it is
probably RG59 or RG59U, both of which attenuate the high frequencies
significantly. If the cables and the fittings are perfect this is
simply due to capacitance and is not likely to cause standing waves.
But then those things are not likely to be perfect, and may not have
been in the beginning.

The only way to tell really is with a sweep spectrum analyser, and
those things will not be on the truck due to cost. The cables could
also be checked for that using a time domain reflectometer, which
would be even better, but look up the cost of one and you'll see why
there was not one on the truck. It's simply too expensive.

It is possible that it is the cables, and you don't need a licensed
electrician for that in most localities because there is no power
involved. But finding someone who really knows how to hide the wires
is not easy. Most higher caliber electricians can do it but they
usually simply refuse because it is a ballbuster. I can do it, but
unles you live nearby it is not going to happen.

Do your neighbors have this problem ? If not get them to run a line
straight into your existing cables and see if the problem persists. It
will have to be attenuated to the same level you have now to make it a
valid test. If it is found to be in the wiring in your unit, which can
only be proven by others in the same complex using the same modem,
with a couple of other requirements, it may be a matter of fishing a
new cable into wherever it splits off into your unit. It is very hard
to be absolutely sure, and the shotgun approach may be a better idea -
which is to replace all the cables in your unit.

Now is another factor, there is more than one carrier frequency
involved in cable internet distribution. These two modems might work
on different frequencies, and due to the nature of the effect of
standing waves that can make all the difference in the world. So now
the question is, since they got you hooked up with the other modem,
why not just leave it that way ? Is there a rational explainaition for
that ? They may have reasons we may never know, but it seems to me if
they want that check every month they should do whatevwer it takes.

So my highly technical ass with all the experience has this advice -
Tell them to take their service and shove it up where, well make sure
it doesn't get a sunburn. Tell them the wires are fine with the old
modem, why change it ? Tell them you are considering other options and
since they can't provide what you are paying for the contract is null
and void - they are in breach. You should see some action.

See to them it's not just the monthly check, it's market share.
Therefore threatening to quit works wonders. Got someone I know a free
wireless router a few months ago, but she is sharp. Not when it comes
to computers, but when it comes to money. She was head of the
purchasing department before she retired and she gets things done.
Threatening to do business elsewhere has alot more impact to companies
like this than one might think. Having more customers does alot, it
can affect stock prices, the D&B rating as well as their advetising
plans. Use it against them if they don't deliver the goods.

J

"Jeff Urban" wrote in message
...

The problem could be standing waves. I don't think any FSM is
accurate enough to detect that. First of all the cable modem requires a
specific frequency, but it also requires the sidebands. In some cases
standing waves can cause complete eradication of 400,0001 Mhz yet
barely affect 400.0002 and 400.0000 Mhz. If this happens the signal
strength is fine bit there is so much distortion in the modulation
that the signal is near unusable.

I don't think you know what you're talking about. Interference effects
generally vary continuously -- they do not occur at one frequency, then
miraculously disappear at another.

Given the age of the cable, it's possible it's deteriorated to the point
where it needs replacement. I was reading something recently -- possibly in
this group -- about the way the outer plastic insulation can actually
"attack" coax dielectric. Or something like that.

On Fri, 22 Apr 2011 13:09:46 -0700 (PDT), Jreality
wrote:

I live in a townhouse. When I first moved in here 6.5 years ago I had
cable internet, but I got a much better deal on DSL so I dropped it
after a month or two even though Cable was faster. A couple of
weeks ago decided I'd try cable internet again. While waiting for a
new modem, they were able to get me online with an old 3Com "Shark
Fine" modem for a few days without problems before a new Motorola
Surfboard was sent to me. When using the old 3Com, the service was
good (no outages), but the top download speed was around 4.7mbs.

When I installed the new Surboard, the top speed was faster. However,
after the first day I discovered that there was an intermittent
problem of the modem losing the signal. What I'm finding funny, is
that when the Surfboard would lose the signal and go offline, the
3Com, if connected, would be able to get online according to the cable
company. I even tried connecting both the Surfboard and the 3Com to
a the same two-way splitter and only the 3Com would get a signal
during the outages. That led me to believe the problem was the
Surfboard. They set up an appointment to have a technician arrive. I
continued to use the Surfboard for a few days with at least 2
intermittent outages per day.

When the tech arrived, he measured the line signal and did a few
things to improve it, such as replacing an unnecessary 3-way splitter
with a two way, and replace a few bad connectors in the system, adding
a filter on one of the lines going into the bedroom which he said was
failing for noise that was likely coming from the TV, and adding a
filter to the little TV in the office which he said was generating
noise. He claimed his machine was still picking up "ingress" (noise)
from the two older approximately 23-year old original cables from when
the townhouse was originally built. While I agree that these two
cables are older and thinner than what is currently used, and
"ideally" would be good to replace, and they may be picking up some
noise if his machine is really telling the truth and calibrated
correctly, etc, but I wouldn't want to replace them unless as a last
resort, because they are snaked through walls. One of them goes from
basement-level to attic above 2nd story and the other from basement-
level in front of house to 1st story at rear of house. I'm not
allowed to have the cable company run wires outside the townhouse and
the cable company won't snake new wires for me internally, so I would
need to hire an electrician to do the work unless I wanted an ugly/
visible wiring job. I fear it would be expensive to have an
electrician install new CATV wires. How much would it generally be
expected to cost to replace these 2 main cables in my townhouse and is
there any risk of damaging anything from having the work done? (NOTE:
In addition, 2 cables going from the attic to 2nd story would likely
need replacement as well) Any idea would the total job should cost?
[snip]

J.

I had problems with digital cable service being unreliable (house is
35 years old - don't know the age of the cables). One thing that
improved it was a bi-directional amplifier.

A generic 'booster' won't work on a digital system, as the cable box
talks back to the cable office to get the program you want. You
should be able to find one on ebay for under $50.

If the problem is loss or poor frequecy response in the old cables,
the amp should help.

I dropped Comcast as cable TV provider because the service was so poor
(pixellation, loss of signal on individual channels, etc). I was
never tempted to use their internet or phone offerings because their
TV up-time wasn't acceptable. I now have AT&T Uverse and the TV is
close to excellent. Among other things, the router (everything is
TCP/IP) logs loss of signal and reports in. The internet download is
7Mbs (700KBs) if the other end supports that speed.

John

The good news is that the modem has managed to remain online
continuously ever since the technician left. So perhaps, for now,
even though he is telling me I should replace the older cables,
perhaps what he did improved the signal enough so that this modem can
stay online. I got above 9 megabits per second downstream in a speed
test last night, which isn't the fastest in the world, but it's triple
the speed of DSL. If the outages happen again I can rule out the
older CATV cables, by moving the modem to a newer line/jack, and then
disconnecting the older cables from the system for a few days.

There already is an amplifier in the system. It was originally
installed when a Cable modem couldn't work upstairs in my office when
I first bought this place and had cable for a month or two. The amp
was originally on the whole system, but my one Sci. Atlanta Box in the
kitchen (actually a kitchen with a den area) eventually started
getting interruptions, and I was told that the signal to the box was
actually too strong so they added a splitter so that the signal going
to that room isn't amplified.

I'm still finding it a little "creepy" that I was being told by the
technician that someone at the cable company can go around at my area
and decide to slap a filter on my entire line at their green box, or
slap a filter on a group of people's lines in my development without
telling anyone. It seems to me that if they did that, then I should
be able to move the modem to one of the newer CATV lines that were
added after this place was built with a wireless wrouter, and insist
that they only slap filters on the older CATV cables as a solution
rather than filtering out my whole system.

They sent me a new modem because it's their policy of sending one to a
new customer. The older modem is like 10 or more years old, and the
speed I was getting wasn't as fast as a newer modem. If I could find
out what frequency it uses, then maybe the new one could be "hacked"
to use the same frequency as the older modem?

The reason I got Cable is because I have DSL too, and it was starting
to really act up, and I got fed up. For the time being, DSL actually
seems like it is back to being reliable. A major piece of equiment
failed on their end that and they had to replace it. In my opinion it
was acting up before it failed completely and causing some major DSL
outages and some days of frequent intermittent outages before they
fixed it. I signed up for Cable while DSL was troublesome, but Cable
proved unreliable too, at least up until now. I'm gonna keep both
for a while because I need a backup in case one has an outage. I
may drop one of the two and get a mobile hotspot as a backup. Is
Verizon any good for that?

I won't tell you who my DSL provider is but lets just say the name
begins with a V and ends in an n, and their DSL has had frustrating
intermittant outages at times. Their tech support is not located in
the US, and if you call them when there is an outage in your area, it
can take several hours just for them to confirm you're not the only
person having a connection problem, and they make you go through all
kinds of steps on your end to try and rule out that it's your modem,
etc.

J.

But finding someone who really knows how to hide the wires
is not easy. Most higher caliber electricians can do it but they
usually simply refuse because it is a ballbuster. I can do it, but
unles you live nearby it is not going to happen.

Unless, you're in the general NYC area, that's probably not
feasible.

Jreality wrote:

The good news is that the modem has managed to remain online
continuously ever since the technician left. So perhaps, for now,
even though he is telling me I should replace the older cables,
perhaps what he did improved the signal enough so that this modem can
stay online. I got above 9 megabits per second downstream in a speed
test last night, which isn't the fastest in the world, but it's triple
the speed of DSL. If the outages happen again I can rule out the
older CATV cables, by moving the modem to a newer line/jack, and then
disconnecting the older cables from the system for a few days.


Who installed the original coax? If it was the builder or an
electrician, it will be the cheapest crap they could find, and was
intended for a MATV feed. Some was low grade RG-59 with a copper
braided shield that wasn't even good enough for the VHF channels.


There already is an amplifier in the system. It was originally
installed when a Cable modem couldn't work upstairs in my office when
I first bought this place and had cable for a month or two. The amp
was originally on the whole system, but my one Sci. Atlanta Box in the
kitchen (actually a kitchen with a den area) eventually started
getting interruptions, and I was told that the signal to the box was
actually too strong so they added a splitter so that the signal going
to that room isn't amplified.


The fact that you even need an amplifier indicates the coax is
defective or substandard.


I'm still finding it a little "creepy" that I was being told by the
technician that someone at the cable company can go around at my area
and decide to slap a filter on my entire line at their green box, or
slap a filter on a group of people's lines in my development without
telling anyone. It seems to me that if they did that, then I should
be able to move the modem to one of the newer CATV lines that were
added after this place was built with a wireless router, and insist
that they only slap filters on the older CATV cables as a solution
rather than filtering out my whole system.


You don't know anything about how a CATV system works. Filters are
used on individual drops to block channels or groups of channels or
services that aren't paid for. There is supposed to be a small
directional coupler to split the cable modem form the TV feeds to drop
the level to what the modem needs, and reduce possible interference.


They sent me a new modem because it's their policy of sending one to a
new customer. The older modem is like 10 or more years old, and the
speed I was getting wasn't as fast as a newer modem. If I could find
out what frequency it uses, then maybe the new one could be "hacked"
to use the same frequency as the older modem?


They all use the same frequencies for uploads and downloads. The
design of the newer modems allows a higher data rate. In fact, their
business customers can get a 40 Mb/S data rate if they want to pay for
it. Road Runner now offers it to residential customers in limited
areas. It all depends on how much spare fiber optics is available in
your area. Internet is carried over 'Fiber Enhanced Cable TV' which
means they use a piece of fiber optic cable for each area, then it is
converted to RF and connected to the system, for that limited area.

http://192.168.100.1/ will display the user interface on my S-A Cable
MODEM.


Name WebSTAR DPC2100R2
Modem Serial Number ********
Cable Modem MAC Address *****************
Hardware Version 2.1
Software Version v2.0.2r1256-060303
Receive Power Level -3.9 dBmV
Transmit Power Level 51.0 dBmV
Cable Modem Status Operational



The reason I got Cable is because I have DSL too, and it was starting
to really act up, and I got fed up. For the time being, DSL actually
seems like it is back to being reliable. A major piece of equipment
failed on their end that and they had to replace it. In my opinion it
was acting up before it failed completely and causing some major DSL
outages and some days of frequent intermittent outages before they
fixed it. I signed up for Cable while DSL was troublesome, but Cable
proved unreliable too, at least up until now. I'm gonna keep both
for a while because I need a backup in case one has an outage. I
may drop one of the two and get a mobile hotspot as a backup. Is
Verizon any good for that?


DSL is a joke in most places. It is a low grade RF over a copper
pair system that uses old and failing copper telephone wire to deliver
the service. If you have the slightest problem with the pair, and it
fails.


I won't tell you who my DSL provider is but lets just say the name
begins with a V and ends in an n, and their DSL has had frustrating
intermittant outages at times. Their tech support is not located in
the US, and if you call them when there is an outage in your area, it
can take several hours just for them to confirm you're not the only
person having a connection problem, and they make you go through all
kinds of steps on your end to try and rule out that it's your modem,
etc.

J.


--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.

Jeff Urban wrote:

The problem could be standing waves. I don't think any FSM is accurate
enough to detect that. First of all the cable modem requires a
specific frequency, but it also requires the sidebands. In some cases
standing waves can cause complete eradication of 400,0001 Mhz yet
barely affect 400.0002 and 400.0000 Mhz. If this happens the signal
strength is fine bit there is so much distortion in the modulation
that the signal is near unusable.

Remember reorienting the antenna to get rid of ghosts in a TV picture
or distortion in an FM signal ? It is the same thing. Standing waves
are very much like multipath in their effects on signal quality. Some
old FM tuners actually had a scope built in to display multipath. The
optimum signal would display pretty much a flat line. Moving the
antenna would cause dips in the line, and that is what causes
distortion. Measuring signal strength just doesn't cut it.

He may have been blowing smoke about the TVs polluting the signal.


Ingression and radiation are continuing problems for CATV system
operators. The cause is two fold. Old or damaged cable, and tampering
or low grade work done by their customers. We used the 'Sniffer' brand
of monitors in our systems in all the service trucks to monitor the
system whenever they were on the road. The installers had to find a safe
place to pull over and call the dispatcher, to get the lead tech out to
find the source as soon as possible.


It's hard to believe the effect would be a big problem if they meet
FCC requirements on radiation. But then it's possible that he was just
attempting to improve the signal as much as possible. Hard to say. I
know people get alot of lip service when what they want is service,
this one is tough to call either way. Maybe he just did what he
could.

But FCC requirements say nothing about antenna input impedance, if
that is off it can cause the standing waves.


Sigh. By design the antennas used in CATV headends are all 75 ohms.
They aren't cheap radio Shack junk, but are single channel antennas made
for the CATV business. Some weigh in the hundreds of pounds and cost
several thousand dollars.


I'm not sure if a filter
would take care of that completely. It seems it should but I know
better, things do not always work as they are supposed to.


Another know nothing answer. Filters have to be designed to work at
75 Ohms, or they don't work right.


If you are talking a "thinner" cable than what is used tody it is
probably RG59 or RG59U, both of which attenuate the high frequencies
significantly. If the cables and the fittings are perfect this is
simply due to capacitance and is not likely to cause standing waves.
But then those things are not likely to be perfect, and may not have
been in the beginning.

The only way to tell really is with a sweep spectrum analyser, and
those things will not be on the truck due to cost. The cables could
also be checked for that using a time domain reflectometer, which
would be even better, but look up the cost of one and you'll see why
there was not one on the truck. It's simply too expensive.


Never heard of a TDR? CATV systems had a sweep test system for anual
'Proof Of Perfomance' testing at least back to the early '80s.


It is possible that it is the cables, and you don't need a licensed
electrician for that in most localities because there is no power
involved. But finding someone who really knows how to hide the wires
is not easy. Most higher caliber electricians can do it but they
usually simply refuse because it is a ballbuster. I can do it, but
unles you live nearby it is not going to happen.

Do your neighbors have this problem ?


What difference does that make?

If not get them to run a line
straight into your existing cables and see if the problem persists.


How do you propose they make sure the signal levels are in the
required range for the cable MODEM?


It
will have to be attenuated to the same level you have now to make it a
valid test.


It would make more sense for the CATV tech to swap ports on the line
tap, or just replace it.


If it is found to be in the wiring in your unit, which can
only be proven by others in the same complex using the same modem,
with a couple of other requirements, it may be a matter of fishing a
new cable into wherever it splits off into your unit. It is very hard
to be absolutely sure, and the shotgun approach may be a better idea -
which is to replace all the cables in your unit.


Sigh. Most in the wall wiring is done by idiots who staple it in
place. My crew had to bust a lot of drywall to replace bad coax, and a
lot was bad becasue 'Bozos 'R' Us' put a staple through the coax, inside
a wall.


Now is another factor, there is more than one carrier frequency
involved in cable internet distribution.

Really? Were in the DOCIS standard is this information?

These two modems might work
on different frequencies, and due to the nature of the effect of
standing waves that can make all the difference in the world. So now
the question is, since they got you hooked up with the other modem,
why not just leave it that way ? Is there a rational explaination for
that? They may have reasons we may never know, but it seems to me if
they want that check every month they should do whatevwer it takes.


The average installer is clueless about cable MODEMs. Some can
barely do more than hook a TV to an existing drop. You need a lead
tech, or a cable internet trained tech.


So my highly technical ass with all the experience has this advice -
Tell them to take their service and shove it up where, well make sure
it doesn't get a sunburn. Tell them the wires are fine with the old
modem, why change it ? Tell them you are considering other options and
since they can't provide what you are paying for the contract is null
and void - they are in breach. You should see some action.

See to them it's not just the monthly check, it's market share.
Therefore threatening to quit works wonders. Got someone I know a free
wireless router a few months ago, but she is sharp. Not when it comes
to computers, but when it comes to money. She was head of the
purchasing department before she retired and she gets things done.
Threatening to do business elsewhere has alot more impact to companies
like this than one might think. Having more customers does alot, it
can affect stock prices, the D&B rating as well as their advetising
plans. Use it against them if they don't deliver the goods.



--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.

One thing that I'm wondering....with regard to the technician claiming
that the cable company would slap a filter on an individual residence,
or group of them, if any ingress is being introduced into their system
by those homes...it seems to me that would prove that they don't
really have a fiber optic system as they claim. In other words, lets
say it's really true that my cables are pulling in some background
noise. If they're so darned concerned about ingress affecting their
precious little cable network (ha!), then it's likely because they
don't really have a fiber optic network from the pole and beyond as
they imply/claim they have. I'm failing to understand how, if there
really is fiber at the pole and beyond, then the ingress would survive
the conversion from a CATV Coax signal to fiber optic signal.

J.

Even in a fiber-optic system, at some point the signal has to be converted
to RF for your TV or set-top box.

I don't know if there are systems that remain optical all the way up to the
set-top box.

William Sommerwerck wrote:

Even in a fiber-optic system, at some point the signal has to be converted
to RF for your TV or set-top box.

I don't know if there are systems that remain optical all the way up to the
set-top box.


No, but Verion's FIOS is fiber right to the house.


--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.

Jreality wrote:

One thing that I'm wondering....with regard to the technician claiming
that the cable company would slap a filter on an individual residence,
or group of them, if any ingress is being introduced into their system
by those homes...it seems to me that would prove that they don't
really have a fiber optic system as they claim. In other words, lets
say it's really true that my cables are pulling in some background
noise. If they're so darned concerned about ingress affecting their
precious little cable network (ha!), then it's likely because they
don't really have a fiber optic network from the pole and beyond as
they imply/claim they have. I'm failing to understand how, if there
really is fiber at the pole and beyond, then the ingress would survive
the conversion from a CATV Coax signal to fiber optic signal.


The fiber may stop a mile or more from your house. All it takes is a
single damaged cable, or loose connector to cause ingression. I used to
design the systems.


--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.

On Apr 25, 9:17*pm, "Michael A. Terrell"
wrote:
Jreality wrote:

One thing that I'm wondering....with regard to the technician claiming
that the cable company would slap a filter on an individual residence,
or group of them, if any ingress is being introduced into their system
by those homes...it seems to me that would prove that they don't
really have a fiber optic system as they claim. *In other words, lets
say it's really true that my cables are pulling in some background
noise. * If they're so darned concerned about ingress affecting their
precious little cable network (ha!), then it's likely because they
don't really have a fiber optic network from the pole and beyond as
they imply/claim they have. * I'm failing to understand how, if there
really is fiber at the pole and beyond, then the ingress would survive
the conversion from a CATV Coax signal to fiber optic signal.

* *The fiber may stop a mile or more from your house. *All it takes is a
single damaged cable, or loose connector to cause ingression. *I used to
design the systems.

--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.

We have Comcast Cable and in our town signals are sent into town from
the head end, a distance of about 10 miles via fiber. It is my
understanding that they arrive at a "node" where they are converted to
RF and then conventionally distributed throughout the town. Our public
access town channels used to return to the head end on a"T" channel, a
frequency usually below channel 2 and then the cable company would up
convert them to some cable channel and put them in the line up. These
days the "T" channels are gone and our public access channels return
to the head end via fiber.

Ingress was a big problem on some of the older RG59U stuff. There is
still aircraft radio, public safety, and low band over the air radio
signals out there that can get into a cable and raise hell with a CATV
system. That's why cable companies really hate that old stuff. Much
of that cable was nothing more than a center conductor surrounded by a
foil shield with a few "drain" wires for show. It was really terrible
crap which didn't even qualify as good clothes line. Lenny

klem kedidelhopper wrote:

We have Comcast Cable and in our town signals are sent into town from
the head end, a distance of about 10 miles via fiber. It is my
understanding that they arrive at a "node" where they are converted to
RF and then conventionally distributed throughout the town. Our public
access town channels used to return to the head end on a"T" channel, a
frequency usually below channel 2 and then the cable company would up
convert them to some cable channel and put them in the line up. These
days the "T" channels are gone and our public access channels return
to the head end via fiber.


The return channels (T) are used for internet, VOIP and to order pay
per view. I used two T channels on the system I maintained near
Cincinnati. One on the main loop, and the other to connect a sub split
to a mid split community loop. The interface between the two cable
companies was a single Hetrodyne Signal Processor to convert the alien
system's channel 12 to T-10, which was fed back to our headend. The
amplifiers required two pilot channels. We used 2 and 12, so our
forward signal was on Ch 2. This was fed into their system, and routed
to their headend. They were already set up with a Ch 6 feed from one
school, so we let them keep control of the loop. I designed the
headend, which was another pair of RCA HSP, as well as the pole mounted
HSP at the interconnect. I set the levels in the shop, and was only off
..1 dB at the interconnect point. Not bad for hardline that was hung
five years earlier, and never spliced.


The biggest problem with the return channels is noise. Every source
connected adds noise to the system. Some return amps were switchable to
disable them, allowing the CATV operator to route a single source to the
headend. This made sense when it was used for nothing more than live
remote feeds. Fiber breaks it into small enough nodes that there is no
need for switching, and in most cases, no amplifier for that direction.


Ingress was a big problem on some of the older RG59U stuff. There is
still aircraft radio, public safety, and low band over the air radio
signals out there that can get into a cable and raise hell with a CATV
system. That's why cable companies really hate that old stuff. Much
of that cable was nothing more than a center conductor surrounded by a
foil shield with a few "drain" wires for show. It was really terrible
crap which didn't even qualify as good clothes line. Lenny


It was still better than the original copper braid coax. Even double
copper braided with a silver plated copper center conductor was
horrible. That wire sold for over $1 a foot in the early '80s. Most
ingression/radiation problems with foil shielded coax is from bad crimps
at the connectors, or wire that has pin holed and water got inside,
which wicks in the dust and salt on the jacket. That eats the foil.


--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.