Fishing tips for finished basement without drop ceiling
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Posted by Ed Nielsen on March 20, 2005, 4:44 pm
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Posted by Ed Nielsen on March 20, 2005, 7:09 pm
Please log in for more thread options Thanks for giving me another fine example of theory that doesn't work. I bought a couple of video baluns. The description reads: FEATURES & SPECIFICATION • Allows traditional 75 ohm coaxial cable to be replaced by one-pair UTP in the CATV, VHF and FM video signal. • Saves extra cost of expensive and space-consuming coax cable and connects RF video equipment to TV, monitors, etc shortly. • 100% tested for reliability & durability to quarantee signal integrity. • Command Rejection: -20dB or higher at 40-500MHz. • Insertion Loss: CATV channels 2-61 <= 3db. • Return Loss: -18dB or higher to 10-550 MHz. • Bandwidth: 5 MHz to 550 MHz. • Distance(Max): 100M via Cat5 UTP. Signal level at my outlet is ~11dBmV. Connected 1 balun to the outlet in my TV room and the other to my digital cable box. Then I connected them with an old 14' CAT5 patch cord. Tried it with a new, 7' CAT5e patch cord still in the bag. Both cables yielded comparable results, which were horrible. Not 1 of my locals was watchable (multiple images that were so bad that sometimes the DCT couldn't even process the signal) and there was not 1 channel (out of ~70 analog) that was even acceptable. Cable channels in the mid 60s through mid 70s where there is a local UHF channel occupying part of the same bandwidth can't even be processed. No picture. Channels 95-97, which are in the broadcast FM band, were the same. No picture. Not 1 digital channel could even be processed at all. Nothing at all on any of the ~190 digital channels to which I subscribe (including Video on Demand, of course). I've attached some JPEGs for your viewing pleasure. In the event that the attachments don't go through, they can also be seen at <http://www.cencom94.com/gpage.html12.html>.
Perhaps one of these days soon I'll pull out my SLM and check the linearity of that portion of the system, though I'm not expecting much positive from that, either. CIAO! Ed N. lawrence.jones@ugs.com wrote: >
>>If a house connected to a CATV system 75 miles away from TV transmitters
>>has ghosting on locals due to a loose connector at the pole (ingress), >>why would one think that there would be no ingress with UTP (which has a >>whole lot less shielding than a loose connector). >
> > Because CATV is unbalanced and thus highly susceptible to ingress > whereas UTP is balanced and thus highly immune to ingress? > > -Larry Jones > > My brain is trying to kill me. -- Calvin | ||||||||||||||||||||||||||||
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Posted by Tomi Holger Engdahl on March 8, 2005, 2:25 pm
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> Unfortunately they want to add video/coax outlets, not data. When I
> couldn't get there soon enough, they setup a wireless network as a > temporary solution for Internet sharing. When I told them that a wired > solution would not benefit them in terms of Internet connection speed, > they decided to make the wireless permanent. > > Is there any possibility of using the existing UTP (currently wired for > telephone only) for video distribution? The UTP wiring used on modern structured cabling system can be used to carry variopus video signals. Modern CAT5e and CA6 wiring can quite easily carry wide variety of signal with suitable adapters. The UTP can carry nicely baseband video (composite video, S-video, component video, RGB etc..), audio signals, digital audio, RF video (antenna/cable TV signals). The secret to sending signals over UTP is to balance them well in order to limit both radiation and noise pick up. This kind of unshielded twisted pair wiring method is used in many CCTV applications nowadays to use existing in-house twisted pair wiring instead of installing new coaxial cable for the CCTV camera. For at least 20 years products have been available capable of transmitting video using UTP wire. Video signal can be adapted to UTP wiring using a special balun transformer between BNC video connector and the wisted pair wiring. This converter converts the unbalanced audio signal to balanced signal which nicely travels through the cable. A similar transformer can be used on the other end of the cable to convert the video signal back to unbalanced format which fits to BNC connector. There are both passive solutions (balun transformers) and active converters available on the market for this application. CAT5 cable is not great stuff for video signals, but with suitable adapters it can work well. The converter will convert the unbalanced video signal to the balanced signal that can nicely go though the twisted pair cable without picking up too much noise or radiating too much interference. The converter will also make more or less perfect impedance matching between 75 ohm video system impedance and around 100 ohm impedance of the wiring. One of the most demanding applications on the market today is broadband video, commonly known as CATV or cable television. It carries a broad range of signals extending from 54 MHz to beyond 600 MHz (usually up to around 900 MHz). Coaxial cable (RG-59 or RG-6) is commonly used for these applications. There are also some products for running broadband RF video through CAT5 or better twisted pair wiring. The solution is to use a small transformer to convert from an unbalanced to a balanced signal on the sending end and and vice-versa on the receiving end. Baluns also make the necessary impedance transformation between coaxial cable (75 ohms) and twisted pair wiring (100 ohms). The use of CAT 5 for wireband RF video has been pretty limited because of quite high attenuation, especially at higher frequencies. The standard specifies attenuation of 24 dB per 100 meters of CAT5 cable, and when frequencies go higher, the attenuation increases quicly. But the higher quality cables, like CAT5e and CAT6, reduce the attenuation considerably. In practice with the suitable amplifiers and suitable adapters you can run the cable TV or TV antenna RF signal succesfully from tens of meters (or up to 100 meters on good conditions) through modern UTP wiring. Unshielded twisted pair is suitable cable to carry balanced signals (balanced audio interfaces in professional equipment), but is far from optimal for unbalanced signals (like home hifi audio interfaces with RCA connductors). To properly transfer unbalanced signal over UTP thesignals need to be balanced (there are baluns for this). If you need to carry digital audio signals, then the signals from coaxial S/PDIF interface can be treated in the same way as video signals (you can use video BNC to UTP adapters for them). One word to the wise: not all Cat5 converters are alike. Not all of them are good and there is a quality difference. They don't all use the same technology to do the signal conversion and you need to compare which one is good enough for your application. When transmitting audio and video signals through twisted pair wiring, use the adapters from the same manufacturer on the both ends of the cable. There are no generic standards how this kind of adapters work, so adapters from different manufacturers are most propably not compatible with each other. Here are some links on this topic: http://www.epanorama.net/links/wire_av.html#utpvideo http://www.nordx.com/public/htmen/pdf/Video_over_Twisted_Pair_Cabling.pdf http://www.kat5.tv/ http://www.lexel.fi/ http://www.svideo.com/coaxbalun.html http://www.infinity-cable.com/icp_balun_catv.htm -- Tomi Engdahl (http://www.iki.fi/then/) Take a look at my electronics web links and documents at http://www.epanorama.net/ | ||||||||||||||||||||||||||||
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Posted by Dmitri(Cabling-Design.com on March 8, 2005, 12:07 am
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Michael Quinlan wrote: > I have a customer who just bought an existing house that has a basic
> structured wiring system installed. Unfortunately, the previous owner > had the basement finished using drywall on the ceiling. Any tips on > adding new cables to the system without taring up the drywall would be > appreciated. You can try to use existing cables as pull strings: tie an actual pull string to the end of the cable and pull it back as far as you can, and then use the real pull string to pull both old and new cables back in place. Also, cut yourself access holes in strategic places in the ceiling. Places where you'd need to change direction of pulling, branch a cable out of a bundle etc. Use generous amount of color matching raceway if cannot pull above the closed ceiling. Also, since a raceway is surely bulkier than the cable it conceals, in some cases it makes sense to use just a color matching cable and hide it under (above/behind/whatever works) decorative elements like borders and baseboards. Improvise ;-) -- Dmitri Abaimov, RCDD http://www.cabling-design.com Cabling Forum, color codes, pinouts and other useful resources for premises cabling users and pros http://www.cabling-design.com/homecabling Residential Cabling Guide ------------------------------------- ##-----------------------------------------------## Article posted with Cabling-Design.com Newsgroup Archive http://www.cabling-design.com/forums no-spam read and post WWW interface to your favorite newsgroup - comp.dcom.cabling - 1428 messages and counting! ##-----------------------------------------------## | ||||||||||||||||||||||||||||
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