adamk

Lolo, By no means did I think your advice was wrong! Apologies if it sounded that way. I know that you and many other people on this forum have a ton of real world experience, which of course I have next to none. It's just that I'm new to all this and looking at things from all angles, and was curious to hear what Belden had to say about this from a theoretical perspective. I was just trying to understand why the foil could be a problem, and I guess I didn't quite get what you were saying earlier about accidentally grounding the core, but that does make sense, and I'm going to find someone expert to recrimp the connectors. Again, thanks for all the time you've spent helping me troubleshoot this problem, and thanks for teaching me so much about this stuff. I'll definitely post updates to this thread. Adam

Out of curiosity, I sent an email to Belden tech support to see what they had to say about tinned vs. bare copper shield, and whether foil was a problem or not. Here's their response, FWIW: Belden product 1694A would make the very best CCTV RG6 on planet earth ! Tinned copper and bare copper on shield is 100% equal and actually tinned copper is slightly better because it will resist corrosion. The foil shield can only help , in no way hurt . The noise is not do to the cable for sure , check your connections...make sure the shield is not shorting against the conductor in any way , or maybe interference from your power cable at the camera etc...again, 1694A would be the absolute best RG6 attainable.

That makes sense about the connectors- I'll try re-crimping them with a fresh set, and get someone to do it who has more practice than me or the person who did them before. Thanks again for your help, Lolo. Very educational!

Interesting. I'm curious, though- given the the tinned copper braid has relatively low resistance (2.8 ohms/1000 ft, as compared to 5 ohms/1000 for 5339X5 and 2 ohms/1000 for 9290) what's the problem with having additional aluminum shielding in addition? My very limited understanding is that the quality and material of the braid is important for two reasons- 1) to provide a ground with low resistance and 2) to shield from interference. From reading some stuff on the Coleman and Belden sites, they've said that the aluminum shield is unnecessary for low frequency CCTV, but never that it would be detrimental. Can you explain what the problem is with having it there, as long as there is also copper braid with sufficient coverage? I never thought there would be so many important little details!

But isn't this 95% copper braid? I thought that tinned copper braid was the same or better, was I misinformed about this?

According to the spec sheet, it has 95% coverage tinned copper braid. Around that is aluminum tape, but that's okay, right? Here's their spec sheet: http://bwccat.belden.com/ecat/pdf/1694A.pdf

This is in the US. I appreciate the reminder about the safety and codes, but all is good. There's no ground for the 28V camera, but the 120V is grounded and all is well secured and installed by a professional rigger. Our operations manager (also a firefighter) inspected and approved everything we've done, so I feel good about it. Not sure what a flicker switch is, but I'll look for it and see if I can make things good with that. Also a good idea to call Pelco. Thanks again- I'll post any new info or images once I capture them.

Thanks Lolo for your help. I'll try to answer your questions to the best of my ability. I did connect another camera to the computer input and saw none of these problems. Both cameras have identical settings. I've played a bit with aperture settings, shutter speed, AGC, etc. Lowering the AGC limit helped a bit- the noise diminished, but so did the picture level. Opening the aperture helped a bit too. Brighter areas seem to have slightly less noise, but it's still there. There's no D/N function that I've found. Pelco also sells a 23X day/night model, but the Pelco rep felt it wasn't worth the extra money for our purposes. Our webcast studio has one and I feel the picture is cleaner, but it also has a shorter cable run and is connected to a professional broadcast monitor. Unfortunately I'm not able to connect that camera to our system to test it. Not sure if the cameras have a B/W mode- I'll check and see next time I'm at the office. I've seen the noise with an LCD, a CRT computer monitor, and a CRT CCTV monitor. As for benching, I didn't do with the computer, as we hadn't purchased it yet. I connected the cameras to the CRT CCTV monitor, but with only a short patch cable. That was a mistake, I should have tried it with the full cable length. I used the same power supplies on the bench as are installed now. One thing I didn't do is connect the ground terminal on the power supply to the ground terminal on the camera. I was told (perhaps mistakenly) that it wasn't important, and also I noticed that most power supplies have no ground terminal anyway. The power supplies are 28VAC, by the way, and mounted about 5 feet away from the camera itself. One other thing that I wonder about- maybe my standards for signal quality are unreasonable. We may use some of the footage for presentation at research conferences so my goal is DVD quality. Maybe that's too much to expect? I'll try to get and post a screenshot soon. Thanks again.[/i]

The problems occurred at initial install. As for electrical devices: 1) the particle detector beam transmitters and receivers are each 200 feet away. 2) The cameras and are about 10' from florescent lighting, but the lighting circuit isn't active during the day when we're recording. 3) This is a huge interactive science museum with literally hundreds of mostly powered exhibits, routing the cables was tough. We chose to run the cables along the high warehouse ceiling rather than close to the ground to avoid electrical interference. Crossing a few conduits was unavoidable, but I've tried flipping various electrical breakers to see if I could get the noise to abate with no luck.

Yep, that I can accept, but the noise is evident when using only the optical zoom- it's just magnified when going to digital.

Both good ideas. I'll take a screenshot when I'm next at the museum and post it here, or somewhere else if I'm not allowed to do that. As for testing the signal at the source, it's a bit trickier- they're mounted 35 feet up, so getting to them requires borrowing a scissor lift, turning off the fire alarm and disabling the particle detectors, etc. I did test them on the workbench before mounting and saw none of this, however it was in a much better lit area without the high contrast situations that bring about the ghosting. Still, it's worth a test. next time I go up there I'll bring a camcorder and record directly from the camera. Also, I did bypass the computer and watch directly from the monitor and saw the same thing. That eliminates the capture card/computer as a problem, but not the cables. Thanks.

Hi all, I'm far from a professional CCTV installer, but I pieced together a system with two Pelco Spectra IV 22x color cameras, feeding a PC with a Geovision GV-2008 card for a museum education research project. All is working as planned, except that I have more noise in the signal than I would like. I'm running 400' of Belden 1694a solid copper core RG-6 cable with Kings crimped connectors. The noise does not seem to be caused by interference- it looks random, with no striping or herringbones, it's just color "snow." Also, there seems to be some color distortion. Very bright areas, especially white spots on a dark background have a prism-like look (rainbows, not solid white) One person who saw it called it "color ghosting" although I'm not so sure. The cameras overlook an area with variable lighting, mostly lit by a huge skylight which can be somewhat dim on rainy winter days. Also, the floor that the cameras look at is painted black, which may trick the cameras into making the image brighter than it really should be. Lastly, the contrast is huge in some areas, with brightly lit exhibits against a dark background. Since the cameras have 23x optical and 10x digital zoom, I've noticed one thing: the noise seems to grow with the zoom level. That is, the snow gets larger as the zoom increases-- at max zoom (264x) the color "snow" spots are huge. I know next to nothing about this stuff, but this leads me to think that the source of the noise is inside the cameras, not in the cabling- If the noise was from the length of the cable or badly installed connectors, I would think that the noise would be constant, no matter what the zoom level was. Am I thinking right? I feel like I've somewhat been able to reduce the noise by limiting the automatic gain control, but this is at the expense of a slow shutter speed or a darker image. Once last observation: the two cameras seem to have identical images, neither has more noise than the other. My questions: 1) Should I worry about cable routing and connectors, or is this a problem with relatively low light, or another problem altogether? 2) Since we have CAT5e cable run to each camera already to control the PZT, is it worth trying to run the signal through one of the two other free pairs with a balun, either passive or active? Thanks in advance for your help. Adam

Hi, I'm not in the security business, so this is all new to me. I'm a researcher/exhibit evaluator at a large museum, and am putting together a system to see and hear visitors as they use interactive science exhibits. I've decided on Pelco Spectra IV PZT cameras (2 for now) and a Geovision GV-2008 card, since we need 30fps at D1 resolution and will add more cameras later, and also need low CPU usage because we'll be using the same computer to transcode and later serve exported video files. I've already learned a lot here but I'm sure I'll be needing more. Thanks in advance!

Hello all, Apologies in advance for my lack of background in this area. I'm a museum researcher, not a security person. I'm looking into security systems as a way to capture 4 cameras simultaneously. Ideally, we'd like to record each camera at full D1 resolution and 30fps, but are willing to accept compromise on one or the other if necessary. Also, because we need to use Mac-only analysis software that uses Quicktime as an engine, we need to be able to create files that are playable with Quicktime with specific characteristics- codec, keyframe rate, etc. Finally, it would be nice if the system could control two PZT cameras. The products that have seemed the most promising so far are the GeoVision 2004, and the Aventura line, as they both produce high quality video. The problem has been that I've been unable to transcode the files they produce so that they're playable with Quicktime. Any suggestions on how to do this? I can get the GeoVision files to open with Windows Media player and RealPlayer (both directshow based) but neither of these programs has provisions for encoding, so I can't create a Quicktime compatible file with them. The Aventura files won't play with anything except this little player they sent me. When I tried to open the file with Windows Media Player, it didn't recognize it as a movie file. The sales rep sent me a codec installer, which let WMP open the file, but there's no image, and my requests for more help from them have been ignored. Am I barking up the wrong tree here? Any suggestions on different approaches to meet our requirements are really appreciated. Thanks!