On 2/8/2012 2:47 PM, Dave Platt wrote:
In ,
wrote:
I'm on a boat, about 170ft from the utility post.
Recently our cable company switched to the wonderful world of
Digital TV. I got the new digital converter and had no picture.
I took the box back and got a second box, still no picture. So now I
suspect a weak signal and confirm that it is the cable length. The cable
company came out and gave me a better cable than I had installed. At
this point I have a picture but it is intermittent. The signal at the
utility post has 3 outputs and had a four way splitter, I suggested the
cable guy put in two 2 way splitters and give me the stronger (first) tap.
That got my signal to work almost all the time. I'd like to get the
signal to work 100% of the time.
I don't has access to electricity at the utility post, so an amp is
out. Although I could try an amp at the cable box end. Is that reasonable?
I would run two cables if there was a way to make it increase signal
strength.
Getting anymore from the cable company is not an option.
Any ideas to get a better signal?

Adding an amp at the cable box isn't all that likely to work... you
can try it, but don't get your hopes up. Unless the amp has a
significantly lower "noise figure" than the RF front end in the cable
box, all you'll be doing is adding noise... the desired signal will be
stronger, but the noise will be stronger yet.

Something you could do, is add a single-port RF amplifier right at the
utility post splitter, where your tap comes off of the feed. You can
buy amplifiers of this sort which are designed to receive "phantom
power" through the coax cable... you'd install a "power injector" at
your boat, which feeds a DC voltage up the coax to the amplifier.
This is probably your best bet:

- It would amplify the signal before it's attenuated by the 170-foot
cable run.

- It won't require a power supply at the post... just at your
boat, where you already have power.

- It shouldn't interfere with the other taps on the
splitter, even when the amplifier is not receiving power from your boat.

You'd be looking for an "antenna mast" type of preamplifier. The
Channel Master 0068DSB or 7777, Winegard AP-8700 or AP-8275 or
HDP-269, AntennaCraft 10G212, or one of the Blonder Tongue Galaxy III
models might do the job for you. You'll probably want a "75 ohm in,
75 ohm out" model, which would connect directly to the 75-ohm coax.

Hey thanks for the part numbers, I'll look into these.
Mikek

On Feb 8, 12:00*pm, amdx wrote:
Hi All,
I'm on a boat, about 170ft from the utility post.
Recently our cable company switched to the wonderful world of
Digital TV. I got the new digital converter and had no picture.
I took the box back and got a second box, still no picture. So now I
suspect a weak signal and confirm that it is the cable length. The cable
company came out and gave me a better cable than I had installed. At
this point I have a picture but it is intermittent. The signal at the
utility post has 3 outputs and had a four way splitter, I suggested the
cable guy put in two 2 way splitters and give me the stronger (first) tap..
* That got my signal to work almost all the time. I'd like to get the
signal to work 100% of the time.
* *I don't has access to electricity at the utility post, so an amp is
out. Although I could try an amp at the cable box end. Is that reasonable?
I would run two cables if there was a way to make it increase signal
strength.
* Getting anymore from the cable company is not an option.
* *Any ideas to get a better signal?
* * * * * * * * Mikek

PS.

* When the signal fails it seems channel 41 is ok and above 42 it breaks up.
Curious to know if there is an unusual frequency jump between those two
digital channels.

see URL:
http://www.dbsinstall.com/broadcast/vhf_uhf_freq_list.asp
41 is 324 - 330MHz and 42 is 330-336 MHz
cables attenuate more at higher frequency.

By ALL means, if you're going to add an amplifier, add it at the
source location, not at the receiver location
Cheap, but good, ones are available from microcircuits. Can you buy a
line driver from your CATV company?

I suspect the 'better' cable is only marginally better. What is the
EXACT cable you're using? what is its attenuation per foot per MHz?
You can buy extremely low loss coax, but you may have to send in your
first born. Go to a local NRTL [EMC Test Lab] and see if they can
(are willing to) order a length for you.

Find the highest channel you wish to receive and the frequency
associated with that. Now you can balance the amplifier gain with the
cable loss to determine if it will work. Note you already know that
170 ft of ?? cable gets you up to channel 41, so from that number you
can estimate just how much drop your receiver can take before it stops
receiving.

On 2/8/2012 3:03 PM, Robert Macy wrote:
On Feb 8, 12:00 pm, wrote:
Hi All,
I'm on a boat, about 170ft from the utility post.
Recently our cable company switched to the wonderful world of
Digital TV. I got the new digital converter and had no picture.
I took the box back and got a second box, still no picture. So now I
suspect a weak signal and confirm that it is the cable length. The cable
company came out and gave me a better cable than I had installed. At
this point I have a picture but it is intermittent. The signal at the
utility post has 3 outputs and had a four way splitter, I suggested the
cable guy put in two 2 way splitters and give me the stronger (first) tap.
That got my signal to work almost all the time. I'd like to get the
signal to work 100% of the time.
I don't has access to electricity at the utility post, so an amp is
out. Although I could try an amp at the cable box end. Is that reasonable?
I would run two cables if there was a way to make it increase signal
strength.
Getting anymore from the cable company is not an option.
Any ideas to get a better signal?
Mikek

PS.

When the signal fails it seems channel 41 is ok and above 42 it breaks up.
Curious to know if there is an unusual frequency jump between those two
digital channels.

see URL:
http://www.dbsinstall.com/broadcast/vhf_uhf_freq_list.asp

That's helpful. however, I do receive channels up to 484!
Dang, just noticed "Lesbo Euro Trash: Big Boobs" is on 502, but, it's
pay per view. :-)

41 is 324 - 330MHz and 42 is 330-336 MHz
cables attenuate more at higher frequency.

I thought there might be a bigger jump between 41 and 42
because when 42 was pixelating 41 was always perfect.


By ALL means, if you're going to add an amplifier, add it at the
source location, not at the receiver location
Cheap, but good, ones are available from microcircuits. Can you buy a
line driver from your CATV company?


I suspect the 'better' cable is only marginally better. What is the
EXACT cable you're using? what is its attenuation per foot per MHz?
You can buy extremely low loss coax, but you may have to send in your
first born. Go to a local NRTL [EMC Test Lab] and see if they can
(are willing to) order a length for you.


I think I'll try the amp, before spending for better cable.

I think I just found a work around, The station I wanted, 42
is repeated on 428 in HD and it doesn't pixelate when 42 does.
The pixelating problem is rare, only a spall percentage of the time,
but very annoying. Ah, the wonderful world if Digital TV.
Mikek

On Feb 8, 2:18*pm, amdx wrote:
On 2/8/2012 3:03 PM, Robert Macy wrote:





On Feb 8, 12:00 pm, *wrote:
Hi All,
I'm on a boat, about 170ft from the utility post.
Recently our cable company switched to the wonderful world of
Digital TV. I got the new digital converter and had no picture.
I took the box back and got a second box, still no picture. So now I
suspect a weak signal and confirm that it is the cable length. The cable
company came out and gave me a better cable than I had installed. At
this point I have a picture but it is intermittent. The signal at the
utility post has 3 outputs and had a four way splitter, I suggested the
cable guy put in two 2 way splitters and give me the stronger (first) tap.
* *That got my signal to work almost all the time. I'd like to get the
signal to work 100% of the time.
* * I don't has access to electricity at the utility post, so an amp is
out. Although I could try an amp at the cable box end. Is that reasonable?
I would run two cables if there was a way to make it increase signal
strength.
* *Getting anymore from the cable company is not an option.
* * Any ideas to get a better signal?
* * * * * * * * *Mikek

PS.

* *When the signal fails it seems channel 41 is ok and above 42 it breaks up.
Curious to know if there is an unusual frequency jump between those two
digital channels.

see URL:
http://www.dbsinstall.com/broadcast/vhf_uhf_freq_list.asp

* *That's helpful. however, I do receive channels up to 484!
Dang, just noticed "Lesbo Euro Trash: Big Boobs" is on 502, but, it's
pay per view. :-)

41 is 324 - 330MHz and 42 is 330-336 MHz
cables attenuate more at higher frequency.

* I thought there might be a bigger jump between 41 and 42
because when 42 was pixelating 41 was always perfect.

By ALL means, if you're going to add an amplifier, add it at the
source location, not at the receiver location
Cheap, but good, ones are available from microcircuits. Can you buy a
line driver from your CATV company?

I suspect the 'better' cable is only marginally better. What is the
EXACT cable you're using? what is its attenuation per foot per MHz?
You can buy extremely low loss coax, but you may have to send in your
first born. *Go to a local NRTL [EMC Test Lab] and see if they can
(are willing to) order a length for you.

* *I think I'll try the amp, before spending for better cable.

I think I just found a work around, The station I wanted, 42
is repeated on 428 in HD and it doesn't pixelate when 42 does.
* The pixelating problem is rare, only a spall percentage of the time,
but very annoying. Ah, the wonderful world if Digital TV.
* * * * * * * * *Mikek- Hide quoted text -

- Show quoted text -

FWIW, our local cable system just converterd to digital and after
installing the cable boxes I noticed that there were usually about 4-6
drop-outs between 6PM and 11PM. I suspected that the problem was at
their end but they sent out a tech who re-terminated the cables at the
demarcation box outside then changed that splitter from 3 output to 2
output. Inside he trimmed about 2m of excess cable from the wall jack
[inside the wall space] and re-terminated that and installed a new
jumper from there to a splitter [replaced] feeding the two cable
boxes, one feeding the TV the other the VCR. He then measured the
levels and the incoming signal was -10dB [just on nominal] and the
back feed level [at the cable office] was -15dB, again just on
nominal. He said that performance was good down to at least -20dB
incoming. My run is about the same length as yours from the
distribution pedistal and is of lower performance that RG-6.
The number of drop-outs is perhaps slightly less, but a new PVR seems
to handle the drop-outs much better than the cable boxes did so they
are less noticable than before. I have also noted that one particular
commercial has a drop-out in it and it is the same everytime it is
run, again pointing to the problem being at their end.

Neil S

On 2/8/2012 11:00 AM, amdx wrote:
Hi All,
I'm on a boat, about 170ft from the utility post.
Recently our cable company switched to the wonderful world of
Digital TV. I got the new digital converter and had no picture.
I took the box back and got a second box, still no picture. So now I
suspect a weak signal and confirm that it is the cable length. The cable
company came out and gave me a better cable than I had installed. At
this point I have a picture but it is intermittent. The signal at the
utility post has 3 outputs and had a four way splitter, I suggested the
cable guy put in two 2 way splitters and give me the stronger (first) tap.
That got my signal to work almost all the time. I'd like to get the
signal to work 100% of the time.
I don't has access to electricity at the utility post, so an amp is out.
Although I could try an amp at the cable box end. Is that reasonable?
I would run two cables if there was a way to make it increase signal
strength.
Getting anymore from the cable company is not an option.
Any ideas to get a better signal?
Mikek


PS.

When the signal fails it seems channel 41 is ok and above 42 it breaks up.
Curious to know if there is an unusual frequency jump between those two
digital channels.


Are you sure it's a signal strength problem?
The cable guy should have been able to measure the signal at your cable box.
Are the people using the other taps having problems?
If you're on a boat, you might be at the end of the cable run.
In that case, you might be able to get them to crank up the gain in their
distribution amp.
Power at the pole is not a problem. You can get amps that are powered
through the signal cable to your cable box. Getting them to let you
install it
is another matter.
You can get MUCH better wire, for a price.

Signal strength is not the only problem with digital TV.
Reflections in the system can confuse the decoder. Are there
any unterminated cables on the other taps?

I have OTA antenna digital TV. Plenty of signal, but reflections
cause significant drop outs on some channels. More signal won't fix
that. In fact, I have a variable attenuator to REDUCE signal strength.
I tweak the signal level for fewest dropouts.


Might be electrical noise coupled in thru the ground system.

Bottom line is that you pay the cable company for TV reception.
It's their responsibility to provide you with a watchable signal.
You shouldn't have to tell them what to do. They should just FIX it!!

On 2/8/2012 3:12 PM, mike wrote:
On 2/8/2012 11:00 AM, amdx wrote:
Hi All,
I'm on a boat, about 170ft from the utility post.
Recently our cable company switched to the wonderful world of
Digital TV. I got the new digital converter and had no picture.
I took the box back and got a second box, still no picture. So now I
suspect a weak signal and confirm that it is the cable length. The cable
company came out and gave me a better cable than I had installed. At
this point I have a picture but it is intermittent. The signal at the
utility post has 3 outputs and had a four way splitter, I suggested the
cable guy put in two 2 way splitters and give me the stronger (first)
tap.
That got my signal to work almost all the time. I'd like to get the
signal to work 100% of the time.
I don't has access to electricity at the utility post, so an amp is out.
Although I could try an amp at the cable box end. Is that reasonable?
I would run two cables if there was a way to make it increase signal
strength.
Getting anymore from the cable company is not an option.
Any ideas to get a better signal?
Mikek


PS.

When the signal fails it seems channel 41 is ok and above 42 it breaks
up.
Curious to know if there is an unusual frequency jump between those two
digital channels.


Are you sure it's a signal strength problem?

Yes, it is the loss in the cable.

The cable guy should have been able to measure the signal at your cable
box.
Are the people using the other taps having problems?

No other problems, I'm just way down the dock from them.

If you're on a boat, you might be at the end of the cable run.
In that case, you might be able to get them to crank up the gain in their
distribution amp.

Next time they are around I'll ask.

Power at the pole is not a problem. You can get amps that are powered
through the signal cable to your cable box. Getting them to let you
install it
is another matter.
You can get MUCH better wire, for a price.

Signal strength is not the only problem with digital TV.
Reflections in the system can confuse the decoder. Are there
any unterminated cables on the other taps?


Yes that is possible, There are transients in and out so sometimes the
taps are used and sometimes not. I suppose I could make a bunch of 75
ohm terminations, and put on a new one every time it's needed.
However I never noticed a correlation between boats in and boats out.


I have OTA antenna digital TV. Plenty of signal, but reflections
cause significant drop outs on some channels. More signal won't fix
that. In fact, I have a variable attenuator to REDUCE signal strength.
I tweak the signal level for fewest dropouts.


Might be electrical noise coupled in thru the ground system.

Bottom line is that you pay the cable company for TV reception.
It's their responsibility to provide you with a watchable signal.
You shouldn't have to tell them what to do. They should just FIX it!!

Ya, but no. It's in a marina and the marina has a deal with the cable
company.
At this point there is talk about putting up an antenna.
The marina has ten cable boxes for transients that need to be plugged in
and connected (I guess keep them updated). So it has become a hassle for
the marina handle the boxes. I just want to lay low and not rock the boat.

"amdx" wrote in message
...
Hi All,
I'm on a boat, about 170ft from the utility post.
Recently our cable company switched to the wonderful world of
Digital TV. I got the new digital converter and had no picture.
I took the box back and got a second box, still no picture. So now I
suspect a weak signal and confirm that it is the cable length. The cable
company came out and gave me a better cable than I had installed. At this
point I have a picture but it is intermittent. The signal at the utility
post has 3 outputs and had a four way splitter, I suggested the cable guy
put in two 2 way splitters and give me the stronger (first) tap.
That got my signal to work almost all the time. I'd like to get the
signal to work 100% of the time.
I don't has access to electricity at the utility post, so an amp is out.
Although I could try an amp at the cable box end. Is that reasonable?
I would run two cables if there was a way to make it increase signal
strength.
Getting anymore from the cable company is not an option.
Any ideas to get a better signal?
Mikek


At only 170 feet, that should not be a problem. My cable runs down a
utility post, then over 200 feet to my house. It goes to a 2 way spitter
and then about 30 feet to a cable modem. The other end goes to anotehr two
way splitter, one side to a regular TV and the other to a digital box.

No problem with the TV signal at my house, and the internet is around 7 MB
or however they measuer it. That is by my test on the internet and what
they say I am paying for in the speed./


Sounds like they need to send more signal from the main cable to the taps to
your line.

On Wed, 08 Feb 2012 13:00:12 -0600, amdx wrote:

I'm on a boat, about 170ft from the utility post.

Ok, 200ft of coax. Presumably RG6a/u.

Recently our cable company switched to the wonderful world of
Digital TV.

You have been assimilated. Resistance is futile.

I got the new digital converter and had no picture.

Something is wrong. The nominal signal from the cable drop is suppose
to be 0dBm. If there's a splitter involved, they like to crank it up
to about 10dBm. Your 200ft of RG6a/u will drop the signal from
between 4dB at the low end, to about 6dB at the high end. Your set
top box is suppose to operate with a 10dB margin. If you would kindly
disclose the maker and model, it might be possible to find the specs.
Typically, you'll have at least 10dB margin. Even with 200ft of coax,
you should have 4 to 6dB margin.

Drag your cable box and TV over to the splitter and try it on the
incoming drop. If that works, move to the ports on the splitter. Make
sure that the unused ports are terminated properly. If that doesn't
work, call your unfriendly cable company and ask them why they don't
have sufficient level to operate your set top box without the 200ft
cable. If it does work, find a 200ft RG6a/u cable that isn't
saturated with water. Try to get some compressing fittings instead of
the crappy crimp type.

Your unspecified cable set top box may also have some user accessible
diagnostics which include per channel signal levels. You may want to
check those.

I'm not familiar with Knology, but I suspect they do the same thing as
Comcast. With Comcast, the lower 72 channels are still analog in my
area. If so, you can probably plug your TV directly into the cable,
set the TV for cable frequencies, not broadcast, and see if that still
plays.

Hint: Troubleshoot by substitution.

Drivel: I spent about an hour troubleshooting my TV distribution
system, only to find a brand new Type F "barrel" connector, with no
center connections. That which is most obviously correct, beyond any
need of checking, is usually the problem.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

On Wed, 08 Feb 2012 15:41:08 -0800, Jeff Liebermann
wrote:

Your 200ft of RG6a/u will drop the signal from
between 4dB at the low end, to about 6dB at the high end.

Some better numbers for RG6a/u:
Freq Atten
MHz -dB
10 0.8
50 1.4
100 2.9
200 4.3
400 6.4
1000 11.0

The CATV band is approximately 50 to 800MHz. With 200ft of cable, you
should see 2.8 to 16dB of loss. While there may be problem at the
high channels, all the lower channels should work.

The 4 way splitter has a loss of about -7dB.

Picking a random set top box:
http://www.zoran.com/IMG/pdf/Simplify_NextGen_STBs_Solutions.pdf
See Page 3. Sensitivity is -18dBm for 256QAM and -24dBm 64QAM.

At the low end, you have 0dBm in, 7dB loss in the splitter, 2.8dB loss
in the coax, resulting in -9.8dBm to the box. That's much more than
the -18dBm/-24dBm needed.

However, at the high end, things are not so wonderful. 0dbm in, 7dB
loss in the splitter, and 16dB loss in the coax, which delivers
-23dBm. That's 1dB of margin, which is not very good. Still, it
should work on the lower channels.


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

On 2/8/2012 6:38 PM, Jeff Liebermann wrote:
On Wed, 08 Feb 2012 15:41:08 -0800, Jeff
wrote:

Your 200ft of RG6a/u will drop the signal from
between 4dB at the low end, to about 6dB at the high end.

Some better numbers for RG6a/u:
Freq Atten
MHz -dB
10 0.8
50 1.4
100 2.9
200 4.3
400 6.4
1000 11.0

The CATV band is approximately 50 to 800MHz. With 200ft of cable, you
should see 2.8 to 16dB of loss. While there may be problem at the
high channels, all the lower channels should work.

Any idea where channel 428 would be in that frequency range?
That's a duplicate of 4,2 but in HD, and it works when 42 doesn't.

The 4 way splitter has a loss of about -7dB.

Just a point. I may not have made it clear. I had the tech put in two
2way splitters and connect me to the first one. Hoping to gain 3db.
(or 4) and it did make a difference.



Picking a random set top box:
http://www.zoran.com/IMG/pdf/Simplify_NextGen_STBs_Solutions.pdf
See Page 3. Sensitivity is -18dBm for 256QAM and -24dBm 64QAM.

At the low end, you have 0dBm in, 7dB loss in the splitter, 2.8dB loss
in the coax, resulting in -9.8dBm to the box. That's much more than
the -18dBm/-24dBm needed.

However, at the high end, things are not so wonderful. 0dbm in, 7dB
loss in the splitter, and 16dB loss in the coax, which delivers
-23dBm. That's 1dB of margin, which is not very good. Still, it
should work on the lower channels.