On Thu, 9 Feb 2012 08:14:31 +0000, Ian Jackson
wrote:

In message , Jeff Liebermann
writes
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.

Careful! Don't get your dBm mixed up with your dBmV. There's around 48dB
difference! 0dBm is a massive 48dBmV. That would certainly make most
set-top boxes wake up and pay attention!

Oops. All my mentions of dBm should be dBmV. Thanks.

Range of acceptable signal levels. They're similar for DTV.
http://www.dslreports.com/faq/16085

How to check signal levels with a Motorola set top box:
http://www.ehow.com/how_12186368_check-signal-strength-comcast-digital-cable-motorola.html

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

On 2/8/2012 5:41 PM, Jeff Liebermann wrote:
On Wed, 08 Feb 2012 13:00:12 -0600, 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.



The Box is a CISCO RNG100
Only data I know how to get is;
Tuner 537.00 Mhz 2dbmv
TDC 75.25 Mhz 5dbmv
RDC 20.00 Mhz 30.0dbmv Yes 30.0

On the road, will check in this evening.
Mikek

On Fri, 10 Feb 2012 11:47:54 -0600, amdx
wrote:

The Box is a CISCO RNG100
Only data I know how to get is;
Tuner 537.00 Mhz 2dbmv
TDC 75.25 Mhz 5dbmv
RDC 20.00 Mhz 30.0dbmv Yes 30.0


It's the same as the Cisco Explorer 1540C with some features removed
by Comcast.
http://www.cincinnatibell.com/shared_content/pdf/tv/exp1540_uguide.pdf

How to get into the diagnostics:
Press and hold SELECT on front of unit until the MAIL light
starts to flash, then press INFO.
Or
Press and hold PAUSE on remote until MAIL light starts to
flash (around 10-15 seconds), then press PAGE-UP (-).
On some remotes, PAGE (+) might need to be used instead.

I'll guess(tm) that TDC is downstream power, and RDC is upstream
power. (20MHz is in the frequency range used by upstream path).
30dBmV is acceptable as the upper limit is about 55dBmv. Remember,
this is dB's above 1mv into 75 ohms, not dB's above 1mw into 50 ohms.
dBm = dBmV - 48dB
So, your 30dBmv is really -18dBm

The downstream values are also in the ballpark. See:
http://www.dslreports.com/faq/16085
The numbers are for cable modems, but the levels should be similar for
DTV. The typical delivered values should be:
-10 dBmV to +10 dBmV "Recommended".
-11 dBmV to -14 dBmv / +11 dBmV to +14 dBmV "Acceptable".
-15 dBmV & +15 dBmV "Maximum".
5dBmV is fairly is good enough and should result in a usable picture.

See if you can excavate the SNR numbers. Maybe there's RF garbage on
the systems (oscillating distribution amp, ingress, whatever, etc).


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

On 2/10/2012 8:11 PM, Jeff Liebermann wrote:
On Fri, 10 Feb 2012 11:47:54 -0600,
wrote:

The Box is a CISCO RNG100
Only data I know how to get is;
Tuner 537.00 Mhz 2dbmv
TDC 75.25 Mhz 5dbmv
RDC 20.00 Mhz 30.0dbmv Yes 30.0


It's the same as the Cisco Explorer 1540C with some features removed
by Comcast.
http://www.cincinnatibell.com/shared_content/pdf/tv/exp1540_uguide.pdf

How to get into the diagnostics:
Press and hold SELECT on front of unit until the MAIL light
starts to flash, then press INFO.
Or
Press and hold PAUSE on remote until MAIL light starts to
flash (around 10-15 seconds), then press PAGE-UP (-).
On some remotes, PAGE (+) might need to be used instead.

See if you can excavate the SNR numbers. Maybe there's RF garbage on
the systems (oscillating distribution amp, ingress, whatever, etc).

Hi Jeff,
I don't seem to be able to follow your directions, I don't think I
have enough buttons. To get the info I posted, Push and hold the power
button until the power light blinks, then push power again and the info
screen comes up.
I don't know what the MAIL light is, I don't have a select button nor
a INFO button.
Hey started pushing buttons on the remote, found I can scroll through
15 pages off stuuf I don't have a clue about.

Got some "RF Statistics on page 5"
Current FDC
Freq. 75.250
Level 5 dbmv
S/N 29db
Errs/Ave 0/0

Current Qam
Freq. 513 Mhz
Level -1dbmv
S/N 35db
Errs/Ave 11/0 or 11/1 or 11/3 but mostly 11/0

That's all I can see.
Mikek

amdx wrote:

On 2/10/2012 8:11 PM, Jeff Liebermann wrote:
? On Fri, 10 Feb 2012 11:47:54 -0600, ?
? wrote:
?
?? The Box is a CISCO RNG100
?? Only data I know how to get is;
?? Tuner 537.00 Mhz 2dbmv
?? TDC 75.25 Mhz 5dbmv
?? RDC 20.00 Mhz 30.0dbmv Yes 30.0
??
?
? It's the same as the Cisco Explorer 1540C with some features removed
? by Comcast.
? ?http://www.cincinnatibell.com/shared...40_uguide.pdf?
?
? How to get into the diagnostics:
? Press and hold SELECT on front of unit until the MAIL light
? starts to flash, then press INFO.
? Or
? Press and hold PAUSE on remote until MAIL light starts to
? flash (around 10-15 seconds), then press PAGE-UP (-).
? On some remotes, PAGE (+) might need to be used instead.

? See if you can excavate the SNR numbers. Maybe there's RF garbage on
? the systems (oscillating distribution amp, ingress, whatever, etc).

Hi Jeff,
I don't seem to be able to follow your directions, I don't think I
have enough buttons. To get the info I posted, Push and hold the power
button until the power light blinks, then push power again and the info
screen comes up.
I don't know what the MAIL light is, I don't have a select button nor
a INFO button.
Hey started pushing buttons on the remote, found I can scroll through
15 pages off stuuf I don't have a clue about.

Got some "RF Statistics on page 5"
Current FDC
Freq. 75.250
Level 5 dbmv
S/N 29db
Errs/Ave 0/0

Current Qam
Freq. 513 Mhz
Level -1dbmv
S/N 35db
Errs/Ave 11/0 or 11/1 or 11/3 but mostly 11/0


It shows that you have a 6 dB slope, and the high end is 1 dBmv below
the standard level. It also shows a lot of errors in the recovered
data. QAM is the digital TV signal. Unscrambled channels are referred
to as Clear QAM


--
You can't have a sense of humor, if you have no sense.

On 2/12/2012 10:27 AM, amdx wrote:
On 2/10/2012 8:11 PM, Jeff Liebermann wrote:
On Fri, 10 Feb 2012 11:47:54 -0600,
wrote:

The Box is a CISCO RNG100
Only data I know how to get is;
Tuner 537.00 Mhz 2dbmv
TDC 75.25 Mhz 5dbmv
RDC 20.00 Mhz 30.0dbmv Yes 30.0



I just noted I didn't have a picture on ch 42.
I went to the RF page, my 537 Mhz numbers were

Level 6dbmv
S/N 0 db
Errs/Ave 0/7 changed to later 0/1742
Status Unlocked

VS. When it was working

Level -1dbmv
S/N 35db
Errs/Ave 11/0 or 11/1 or 11/3 but mostly 11/0
Status Locked

Mikek

"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.

snip

Getting anymore from the cable company is not an option.

I take respectful exception to that last sentence. My digital cable box is
about 130 cable-feet from the pole. My signal is tapped enroute for digital
telephone, tapped enroute for Internet and then split (by me) so I can feed
analog signals via a disttribution amp serving bedrooms, kitchen and shack.
I get enough from the pole tap to do the job.

Somebody is treating you badly -- maybe the cable company, maybe the marina.
Yes, the approach for you to buy and install an inline, remote-power amp at
the pole is entirely valid, technically. However, that's not in keeping
with reasonable expectations. You needn't roll over so easily. It's
supposed to work.

What -- Are you worried you might offend somebody? That "somebody" seems
quite okay with kicking you in the ankle. Or elsewhere.

"Sal"

On 2/8/12 7:27 PM, Sal wrote:
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.

snip

Getting anymore from the cable company is not an option.

I take respectful exception to that last sentence. My digital cable box is
about 130 cable-feet from the pole. My signal is tapped enroute for digital
telephone, tapped enroute for Internet and then split (by me) so I can feed
analog signals via a disttribution amp serving bedrooms, kitchen and shack.
I get enough from the pole tap to do the job.

I respectfully agree! 8^)

I don't know exactly how it's done now, but when I worked in the Cable
industry many moons ago, we had a lot of adjustment we could make. Even
more, we had variable by frequency attenuators so we could ensure that a
flat signal showed up. There was a lot of signal at the amplifiers, and
if we really needed more oomph, we could put in a distribution amp.
Another amp was really rare.

Somebody is treating you badly -- maybe the cable company, maybe the marina.
Yes, the approach for you to buy and install an inline, remote-power amp at
the pole is entirely valid, technically. However, that's not in keeping
with reasonable expectations. You needn't roll over so easily. It's
supposed to work.

What -- Are you worried you might offend somebody? That "somebody" seems
quite okay with kicking you in the ankle. Or elsewhere.

Yeah, there is something wrong there. For as much as people hate
Comcast, when I had cable internet put in, they replaced all the cable
from the pole to the house, and a lot inside the house. I did talk them
out of replacing the new cable I had put in, but insisted on putting new
connectors on them. The measured all the levels and set them high enough
that I'd be able to add more televisions if I liked.


Time to call the cable company and tell them you want your MTV.


- 73 de Mike N3LI -

"Michael Coslo" wrote in message
...

snip

Time to call the cable company and tell them you want your MTV.


No way to know from here, but they may not be able to add another amp.

While I was looking for something else, I lurched into this page:

http://www.cisco.com/en/US/products/hw/cable/ps2217/products_white_paper0900aecd800fc94c.shtml

While its intended audience is Internet modem designers, the noise
discussions are informative with regard to other signals, too.

My point: When you try stringing too many amps in line, the signal-to-noise
ratio (SNR) eventually becomes unacceptable. (Remember the acceptable SNRs
cited for 256 QAM and 64 QAM.)

"Sal"

"Sal" wrote in message ...
My point: When you try stringing too many amps in line, the
signal-to-noise ratio (SNR) eventually becomes unacceptable. (Remember
the acceptable SNRs cited for 256 QAM and 64 QAM.)

"Sal"


Sorry. I should have said carrier to noise ratio (CNR), not SNR. SNR
applies to post-detection signals. i joined the digital world late in life.

"Sal"