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:
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"
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"
In message , Jeff Liebermann writes
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!
>-- Ian
They go to two other outlets, that are used for transient boaters. sometimes they are used and sometimes they sit unterminated. I have not seen my problem better or worse when boats are in or out. But I have several 75 ohm F connector terminations. It's worth a try. Mikek
Never noticed any ghosting with the analog. Mikek
I'm sorry I got that wrong, they are F compression connectors. Coax was from the cable company.
My drivel:
At my home, knology recently upgraded there system for faster internet. A cableman said he heard me radiating a block away. he came in and changed 7 crimp type connectors in my attic a couple of cable runs. Speedtest.com went from 6 Mbps to over 11 Mbps with just those changes.
Oh, if that is the fact, I may get me some browny points, If I can get the signal up to snuff, then put the vcr back in the line, my wife could record her soaps again. That would get me 15 seconds of hero status! Mikek
Just an addition to the termination debate, the marina has about 150 taps, I'd be surprised if 30 of them are connected to a tv and the rest are unterminated. The line generally goes to the utility pedestal into a 2 way splitter and then about 1 ft of cable connects it to the 2 taps for the boat owners. Mikek
Yup, try it. Transient boaters will most likely not carry the required set top box around but use the lower analog channels or nowadays maybe UHF digital. Sort of "basic cable". Then the TV is connected directly and those rarely have a true 75ohms input.
-- Regards, Joerg http://www.analogconsultants.com/
Yep, that's the way it works. Compression type F connectors work well. Crimp type are junk. The catch is that there are probably 100 different types of connectors, each with their own compression tools, intended to fit about 8 different types of 75 ohm coax (RG6a/u, RG59/u, single shielded, double shielded, quad shielded, direct burial, etc). Mixing connector types and cables doesn't work. I got fed up and "obtained" a 1000ft roll of double shielded RG6a/u, a big of matching F, BNC, and phono connectors, a compression tool, a stripping tool, and replaced all the junk cables in the house.
I'm sure it's true for Comcast in Santa Cruz, CA. No clue on other areas. The grand plan is to move all the analog channels to digital area by area:
Unfortunately, your area may be one of those that have moved to all digital. Hard to tell from here.
Can you determine if the marina is using a distribution amplifier driving a big splitter, or is using a single cable trunk snaked through the marina, with taps (directional couplers) at various points? If taps, it's easy to install too many taps, or miscalculate the tap type, resulting in level variations along the trunk.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
How to Check Comcast Signal Levels
I'm not sure if this works on the newer set top boxes, but give it a try.
-- Jeff Liebermann snipped-for-privacy@cruzio.com
150 Felker St #D
Oops. All my mentions of dBm should be dBmV. Thanks.
Range of acceptable signal levels. They're similar for DTV.
How to check signal levels with a Motorola set top box:
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
. s ?
s up.
Google your cable box model. You should able to find ifo on how to pull up a menu that shows signal strengh. -60dbm is about where my sigal starts droping out
Jimmie
Not really. If there are long unterminated 75 ohm cables after the splitter, they are a crude termination. The splitter's backmatch eliminates ghosting from reflections from the unterminated end.
-- You can't have a sense of humor, if you have no sense.
Those are 'Equalizers' and used to cancel the cable losses. There is some adjustment in the trunk amplifiers, but some brands just used a plug in equalizer marked with the rolloff in dB while others had both. The coarse plugin, and a variable equalizer to level the trunkline for 'Proof of Performance' tests.
-- You can't have a sense of humor, if you have no sense.
In your opinion. If they are delivering the level called for in their franchise, they didn't screw up. It has always been up to the customer to pay for or provide extra equipment for non standard installs.
-- You can't have a sense of humor, if you have no sense.
A power inserter is used to put 9-28 volts DC on the coax, depending on the amplifer you use.
-- You can't have a sense of humor, if you have no sense.
Google your cable box model. You should able to find ifo on how to pull up a menu that shows signal strengh. -60dbm is about where my sigal starts droping out
Jimmie
=====================================================
Yes, but be mindful of the difference between dBm and dBmV. The cable industry often deals in levels on the dBmV scale.
There are places like this ...
where you can see some conversion equations. Jimmie's -60dBm equals -11.25 dBmV. Same power level -- different scale.
I have long known level requirements for the TV tuner's cousin, the cable modem. The common DOCSIS 2 cable modems are usually spec'ed for -15dBmV to
+15dBmV and the smart operators try to keep inside +/- 12. Thus, you can see that Jimmie's -11.25dBmV is near the low limit and that dropouts become more likely in that neighborhood.I little bit of google snooping revealed that DTV cable boxes would like
0dBmV and will usually be okay with -10dBmV to +10dBmV. Almost the same.i hope this helps.
"Sal"
"Sal"
If their company cable box doesn't deliver a useful and reliable signal I call that screwed up. One pays for a service and expects to either get it delivered as promised or money back.
Mike's install does not sound non-standard. 170ft cable drop towards premises which is fairly normal, plus the cable company's set-top box.
-- Regards, Joerg http://www.analogconsultants.com/
Grow up. That is an excessive length drop. A standard drop is under
100 feet. You think you know everything, and that the world has to live by your rules. You don't, and it doesn't. I'll bet you've never even seen a CATV franchise, or the dozen of pages of specifications agreed to by both the CATV company and the local government. The CATV company isn't a Santa Clause machine, and local governments know why there are limits to the service provided. If there were't, no one could afford to build or operate a CATV system. You've never designed a headend, or a physical plant If they build to supply higher port levels, it has to start at the headend, and requires closer spaced trunk amplifers. The system noise goes up from all of the cascaded amplifers, and the equipment runs hotter, withj a very reduced service life. When you can design an RF distribution system of more than 500 MHz bandwidth and has over 10,000 output ports, with the gain stabilized to a couple dBmv 20 miles from the headend and over a range from sub zero F to + 100 F then you can tell me I'm wrong.One headend I designed and built was only off by .1 dBmv at the test port on the first trunk amp which was a half mile from the head end. If you can do better than that, I'll listen to you and your opinions
-- You can't have a sense of humor, if you have no sense.
Cool! You seem to know what you are up to.
Can you put rough numbers around what you mentioned? Like what are providers legally required to deliver at the far end of the drop?
Thanks.
tom K0TAR
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