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Increasing Cable TV signal strength
On Wed, 8 Feb 2012 20:17:11 +0000, Ian Jackson
wrote: In message , amdx writes 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. Despite your long 170ft drop cable, were you getting good analogue signals before the change to digital? If so, it could be that something is not right. Normally, even if you have had only fairly mediocre analogues, the digitals are good. Otherwise.... It sounds like your signals are just too weak. As things are, and if you can, the obvious fix would be to overcome the substantial loss of the 170ft drop cable by fitting an amplifier at or near the utility post (not at your end), and power it with low voltage via the coax from your end (ie similar to a line-powered masthead antenna amplifier). However, you would need to consult with the cable company to see if they were OK with letting you do this. It could be that they might be able advise you on the most suitable amplifier to use. It's not rocket science, but you have to be a little careful not to break any of their rules and generally do anything they don't approve of. The cable company probably has amplifiers that can be powered over the cable run. If not, those amps can be found on ebay. Be sure to get a bidirectional amplifier because some systems send the control signals back up the cable to the cable company (Comcast in the southeastern US, for example.) John |
Increasing Cable TV signal strength
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 |
Increasing Cable TV signal strength
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. |
Increasing Cable TV signal strength
"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. |
Increasing Cable TV signal strength
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 |
Increasing Cable TV signal strength
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 |
Increasing Cable TV signal strength
"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" |
Increasing Cable TV signal strength
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 |
Increasing Cable TV signal strength
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. Looks like the cable guys screwed up. a. They should be putting enough signal on that cable to overcome the loss. b. They should be able to measure the amplitude of pilot signals at your end of the cable and tell you how much above minimums they are. 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. If all else fails you may need an amp. What Fred means with drop amp is usually called a "mast preamplifier", like this: http://www.amazon.com/Uhf-Vhf-Antenn...748729&sr=8-20 I don't know this particular one but essentially it should be weather-proof. It gets its DC voltage via the coax, from a wall wart that would plug in at your boat. So no need to run a power supply cable up there. Don't go for too much gain. This dreaded DTV falls apart rather easily on the slightest distortion or cross-modulation. Not sure if the above amp can handle that. You might need a more expensive one. Michael Terrell might know which ones are good. What matters is dynamic range. Also, make sure you have a perfect 75ohms match at your end. The cable box from the cable company should provide that. if you have Internet and/or phone through them as well check that connection so it doesn't cause reflections. On a boat at sea stuff can corrode quickly. Oh, and don't dare to watch that boobs channel while your wife's on the boat :-) -- Regards, Joerg http://www.analogconsultants.com/ |
Increasing Cable TV signal strength
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. Now remember the problem is quite intermittent, but seems to be happening almost daily for short periods. 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. There should be no water in the cable, it's only a couple of months old and both ends have crimp on connectors and are located in a box or boat. 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. It does have diagnostics, I'm not sure if it is each channel though. But I can get some info out of the box. I'll be there Friday and I'll get that info and the model of the cable set top box. 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. I'm using Comcast at the boat. We are lucky here (I think) in that we have a choice of two cable companies. 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. Drivel is good. |
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