Thomas 0 Posted March 10, 2005 So on the way home I was doing some thinking and now I have some questions about Cat 5 for CCTV. 1. I know you can use two pair for video and power but could you use a third pair to power something else? Does that pair have to be the same type of power? 2. Can one pair be used for RS-485? Share this post Link to post Share on other sites
rory 0 Posted March 10, 2005 only thing you should not do, is run 24vac in the same bundle as telco or data. though 24VAC can be run way longer that 12VDC. Always should double up the power on 50'+ runs. Share this post Link to post Share on other sites
Thomas 0 Posted March 10, 2005 Alright, so it sounds like RS-485 would work? Share this post Link to post Share on other sites
rory 0 Posted March 10, 2005 yeah, what are you using to transmit the video? Without an amplifier/EQ anything over 50' is going to have video loss of image quality, unless you use an amp/equalizer. It still looks okay up to 500', say using a balun, but I personally would never use baluns again, only amped / eq's. Even at 150' with a balun (2 different brands) i can notice many issues. If I double up the video pair, could get better, but was trying to keep the extra cat5 for some add ons later. When I get the FM systems Camera Master, ill do some more research on the exact loss amounts. Check out both NVT and FM Systems for more detailed info on using Cat5 with CCTV. FM Systems has some great unbiased artcles on this. http://www.fmsystems-inc.com/articles.htm rory Share this post Link to post Share on other sites
VST_Man 1 Posted March 10, 2005 I'm using unpowered Balun's with no problems. I run video, RS, and power down the same Cat5. Doubling up on the power only needs to be done for the longer runs, which I've found to be a neat topic to discuss as some say 50 ft. and others further no problems. AC can be pushed further without any loss problems like DC so I've pushed AC out as far as 300 without any problems. DC on the other hand starts to degrade at 200 so I won't push that. The bottom line on Cat5/Balun is you need to know the cable and the Balun's specs so you can figure out the max. Some Balun manufactures say to double the power, others do not. Depends on the manufacture and cable. ISC West is having a good "class" on this subject so if your out there you may want to sit in? Also; the power supply makes a difference also. I've seen the cheap power supplies, AC & DC, subject the system to line loss and noise resulting in poor video, slightly out of focus. I carry a "Clean" power supply with me to quick connect systems to so that I can eliminate dirty power problems right off the bat. Saves me lots of time. Cat5 is more sensitive to crosstalk/noise from other sources and RG seems to have it's own unique issues like bending beyond manufactures recommended specs or else you will cause reflections in the signals. Alomst all poor video calls are bad connectors, cross talk, or bad cable, in that order. A great example is on DVR systems using RG; the "nest of BNC connectors usually are stacked on top of each other. The BNC connectors that touch each other can cause poor video. But, if you tape them up the problem disappears. Not written anywhere, but, things you learn on the road. later/ Share this post Link to post Share on other sites
mcs 0 Posted March 13, 2005 Baluns can do - 4 cameras from 1 x cat 5 ie 4 pairs... no power required, (Passive) 600m b/w 300m colour amps can extend distances acheived, - (Active) can acheive 2400m Less cross talk. less prone to interference at 100 ohm impedence TIP: watch earth loops in buildings seperate housings from metal buildings etc when using a dvr , can save some headaches later- i managed 200m from colour at a site, and i scotch locked two boxes 610m cat five and stuck a balun on each end and got clear as day picture from an infrared cam.... cheers Share this post Link to post Share on other sites
