April 21, 2016
First of all let me tell you right off I am a newbie. I am an IT Professional by trade and have recently been thrown into the security cameras, alarm and door access control systems.
I have a client who run an apartment complex in the center of the property is the main office/clubhouse with two 16 channels DVR and two 16 port power supplies. Besides the Main Office/Clubhouse building, there is 7 apartment buildings (Building A - G)
Location/# of Cameras
- Building A/4
- Building B/5
- Building C/6
- Building D/3
- Building E/3
- Building F/3
- Building G/3
Some of these cameras are some distance away from the centrally located Main Office/Clubhouse that when you look at a live feed from the DVR, the video signal is very bad. What I want to know is there a maximum distance for a video signal and for power cable. They are using the Siamese cable that has the video/power together. I hear that power will drop or degrade over a certain distance. I am sure the same is true for video signal.
I also have one other problem, let say you are getting a bad picture on one of the channels on a DVR, let say "Channel 1". You unhook cable from DVR and hook it up to a camera viewer and the picture looks great. What could be causing this problem?
Thanks. I will try to post up a map of apartment complex and distance from Main Office to furthest camera later today.
May 15, 2015
Hi Randy -
First of all - the coaxial cable can be a factor. It needs to be copper center conductor and 95% copper shielding. (the braided part)
Do not try to use coax that is used for cable TV - too much aluminum/steel components for good signal.
Max distance you want to run coax for CCTV is around 700 ~ 800 feet. After 800 feet your signal will start to visibly degrade.
The siamese part of the cable should be 18/2 conductor - and this is the 'iffy' part. The 18/2 carries your power to the cameras. If the cameras are 12 volt DC - you have about 150 feet maximum distance before you start to see voltage drop. The higher amperage draw the camera has - the faster the voltage drop occurs. So your power distance is far more limited than the video signal distance.
For interference - anything that generates RF is a factor to avoid - high power lines / flourescent light ballasts / etc. can cause interference with the video signal.
For your question about the camera viewer - usually a camera tuner or even a CCTV monitor will have a pre-amp to boost the incoming signal and stabilize it. The DVR does not have that pre-amp - it depends entirely on the camera signal strength.
Bear in mind - these figure pertain to analog CCTV equipment. Newer systems like IP and HD-CVI etc. may have different requirements.
let us know if that helps.
April 21, 2016
Thanks for the reply. As you can see from the picture below. This is the apartment complex layout and you can see the cable runs from the left side of the Office. The first run goes from Office to Building A, then to Building B, then to last building in the run, Building G and the last camera is approx. 1103 feet from the DVR and the two 12 VDC power supplies in the Office. The 2nd run goes from the Office to Building F for an approx. 567' to last camera on that run. The 3rd and 4th run goes out of the office up in-between Building C & D and then some of the cables goes into building C, then rest goes into Building D & E to the last camera at approx. 994'. Now here is the clincher. In Building D and E, they each have 3 cameras in each building. Also D & E, each have there own 4-port 12VDC power supplies.
This doesn't make sense. But I was thinking, why not put power supplies in each building so that you don't have any problem with getting power out to the cameras. Each apartment building is approx. 245' long and if I put the power supplies in the center of each building, that would be 122.5' to each end of the building.
Does that sound like a better way to do it?
Thanks for any input.
P.S. I hope the picture shows up on your screen. The preview looks small.
May 15, 2015
Randy, are these just analog cameras? If so, then you are definitely pushing beyond the limitations of an analog system.
I am surprised that you are getting any signal at all from building G at 1103 feet. The only way I think that is possible is if you have Cat-5 cable with video baluns at each end on those runs. Otherwise, anything over 800 feet should be grainy or black and white at best, and video dropouts or no video at all at the worst.
I think your plan to power the cams from more central locations in the middle of each building is a good idea. That would get power issues out of the picture for the most part.
Looks like you got stuck with kind of a nightmare to figure out and fix.
I guess a good starting point would be to get the power set up as you describe - that should help.
Then take a close look at the cabling - is it standard coaxial or Cat-5 with video baluns?
An easy way to tell is look at the DVR where the cameras video cable plugs in - if it is a standard coax, it will be terminated with a BNC connector clamped directly on to the coax sheathing. If it's baluns - you'll see two wires coming from the cable to a small device with a BNC on it connected to the DVR. If you have those baluns - then your power strategy may fix the problem.
If it's standard coax - then you have some decisions to make - like whether to replace the cabling or replace those cameras and possibly the DVR itself to get you into newer technology that can handle those distances. (HD-CVI cameras at 1 megapixel can travel up to 1600 feet over standard coax with no issues - but you would need an HD-CVI capable DVR for that.)
Sometimes I get a little long winded..ha ha! Let me know if that all makes sense.
April 21, 2016
Thank you so much for your reply. Yes, your message make sense. It is standard coax with BNC connectors on each end. Yeah I wandered the same thing, how can some of those cameras be powered at such distance. But you are right, so of the pictures are grainy or weird off-colors. I do have a couple of cameras that the pictures are just black, but I haven't figured out which cameras they are yet.
My plan of attack is one building at a time. Work my way from office out toward the end of the line. Thanks for your help and suggestions. I am planning on replacing the DVR anyway. I did get permission from the owners to do that, because the current DVRs are 15 years old. Need to get some newer technology in that place.
Your suggestions are welcome.
Do you have a clue as to the quality of the cable that is being used between these runs? If you cut the end of the cable off you should be able to look at the center conductor and if it is a shiny silver color, the video will struggle at your distances on video transmission. You would be better suited sending 720p video these distances and the closer distances under 750' you can run those at 1080p. Bear in mind that the quality of the cable will play into the effectiveness of the video transmission. If you cable is shiny silver in the middle it means that you have CCA or Copper Clad Aluminium cable in place and you can take 40% off on the distance to be able to transmit video as there is not enough copper in the cable to make transmission truly possible in HD. If you centrally locate your power supplies in each building, you should be a lot better off with your video quality.
Personally, I would simply put a recorder in each building with a wireless link back to the main off, then use the FREE CMS software on a PC at the main office to view all the recorders. There is a way to put an NVR at the main location and stream the channels into it as your central management device. In a situation like this, I would have smaller HDDs in the remote units and large HDDs in the central unit. The remote units having a small HDD will help, if something happens with the connection between buildings with the wireless link. The link we use heavily is our TP-LOCOM5 http://www.securitycameraking......-prd1.html .
I hope this helps you.
April 21, 2016
I thought I better give everybody who have replied to this thread an update. This project and other projects at this client site kept us pretty busy at times and then at times things were on hold due to late payments. All-in-all, we ended up putting local power supply in each building. Re-doing some cables ends and replacing some of the cameras with better cameras and put better lighting in some areas to help improve visibility. Putting the power supply in each building was the biggest improvement to the whole system.
Thanks for all of your feedback.
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