Hard Knock lessons from a vet of CCTV systems large and little
When you are looking at designing an IP camera system traditional rules for wiring the cameras and recording the cameras go out the window. Below I have listed 3 design traits that have changed from conventional coaxial-based camera systems to IP based camera systems.
Rule one : Infrastructure Design
Two years back I was presented with a big camera system that needed over ninety cameras in a building that was over 750,000 square ft. The challenge, using standard camera design, was wiring each camera back to a central location where the command console was located. In some examples, camera locations were over 1,500ft from the command center. Since coaxial wires limitation for RG59 and RG6 wire are between eight hundred and 1000ft, solving the distance limitation problem was critical. Using the methods open to me at the time, I had a choice between fiber optic wire or UTP ( unshielded twisted pair ) wire. Although fiber optics generally will produce a clearer picture with less distortion, it was cost prohibitive for the project. I chose UTP wire and with an active receiver at the command console and passive transmitter at the camera. This provided for wire runs of nearly 3000ft. UTP wire is just CAT3 or CAT5 cable ( commonly called Ethernet wire ), which is used for telephone and data networks. One of the 4 pairs of wires sends video down the wire. The twisting of the wire provides its unique benefits. This gives the cable its name of unshielded twisted pair. At the time, now more than 4 years back, this was the best solution for the application as it met the criteria for broadcasting the video and met the client's budget.
IP Video changes everything.
Using IP cameras presents a new set of rules for transmitting video. Where before we were able to transmit a video signal up to 1000ft using coaxial wire we are now restricted to only 300ft or one hundred meters. At first, this may appear to be a disadvantage. To anyone that is acquainted with designing a P. C. network it is apparent this layout is essentially a benefit. Imagine the application below:
You have 5 cameras you want installed. They're all located along a back wall of the building looking out to the shipping and receiving area. The recorder is found at the front of the building in an IT closet. Under standard video design, all 5 cameras would have a coaxial wire installed from the camera to the recorder. In this example, let's say the distance is a mean of 500ft from the recorder to a camera. Five cameras at 500ft each would require 2,500ft of coaxial wire. Using a network solution the following wiring would be needed. A single wire, generally fiber, would be pulled from the front of the building to the back. At every end of the fiber, there would be a termination point. The termination point at the front of the building would be considered the Main Distribution Frame or MDF. The point at the rear of the building would be the Intermediate Distribution Frame or IDF. An IDF is outlined as a location between the MDF and the end device, in this situation the camera. All the cameras would be wired to the IDF location. For our example, we'll say it's an average of 100ft from each camera to the IDF. We'd require 500ft of network wire. Conclusion is that rather than pulling 2500ft of coaxial wire you are installing 500ft of CAT5e wire and 500ft of fiber.
The Big Bonus behind IP Video
The chief benefit behind a network solution is scalability, that leads to important long, and short term savings. When you have 5 locations all with 5 cameras and all 500ft from the recorder, the costs add up quickly with traditional systems. In this scenario the cost savings can actually begin to add up. Going back to our example for a minute, let's say you need to add a new camera to view the inside shipping door. The infrastructure is already in effect. Now all that is's needed is pulling a single CAT5e wire from the new camera location to the IDF. Perhaps this is only 50ft away. Using the old design, you'd need to pull another 500ft of coaxial wire back to the recorder. This adds up to a cable savings and a significant work cost reduction.
Rule 2 : PoE - The'Power' of a Single Cable
PoE or Power over Ethernet is just the transmission of power together with info over a standard Ethernet wire. In a Power over Ethernet system, a PoE network switch provides up to 15Watts of power to the end device. This can be a telephone, camera or any other device that sits on a network and needs less than 15 watts of power. When planning an IP camera system you need to look for cameras that use this technology. There are 2 basic benefits when using PoE for your system layout.
Benefit one : just one wire is necessary to each camera for both power and video transmission. Vs a standard camera system that uses a Siamese wire for both video and power. A Siamese wire has a coaxial RG59 wire and sometimes a 18 gauge two conductor wire molded together to form a single wire. This gives the appearance and simplicity of pulling a single cable to each camera. The drawbacks to Siamese wire compared to CAT5 wire is it is noticeably more expressive. Siamese wires contain more copper, which is a pricey commodity in today's market. Siamese wire is also more difficult and awkward to install.
Benefit 2 : No extra power supply is required for powering the cameras and it simply needs a single termination at the camera and switch location. These two extra features lead to the same benefits : cost benefits and a more flexible and scalable system solution. Scalability and space necessities are becoming an enlarging concern for many IT departments. When adding a network camera system the potential rack space needed for the present as well as future can be extremely critical when designing a system. Using PoE can reduce space and reduce heavy, inflexible bundles of wires.
Rule 3 : Centralized or Edge Recording
There is no wrong or right when it comes to using edge recording or centralized recording. Most of your call will rely upon your own application and existing network infrastructure. A hybrid of the 2 styles may be the best solution but this can add further cost and restrict your available camera options. In a meeting with a college district, I was asked about which solution was better. I replied that I felt neither was a better solution ; both solutions have their benefits and it depends on the application. During my meeting I described the following advantages and disadvantages of each.
Centralized Recording:
Imagine you have a company which has five buildings ranging in size between 10,000 to fifty thousand square ft. All 5 of your buildings are found within a large economic park. Each building has a controlled number of fiber optic wires between them. Your company has a main server room found in the biggest of the five buildings. The IT department manages the server room and there is limited prohibited access to that room. The remaining 4 buildings are accessible via fiber from the server room.
For this example, centralized recording offers you the most inexpensive and scalable solution. Centralized recording works well here. There is a main server room and all the buildings are connected thru locally owned fiber. Employing a single recording location is inexpensive because all the recorded video is stored at a central location. A single server as against 5 servers ( if using edge recording ) will record the video, leading to a serious cost benefits. In each building, PoE network switches would connect to the cameras. The fiber optic wire would transmit the video back to the central server room for recording. This solution is also very scalable. Adding a camera to any location in the 5 buildings is as simple as connecting a camera to the nearest PoE switch. In this actual application, centralized recording fits best thanks to the environment and infrastructure available. A disadvantage of centralized recording is if a fiber is cut between any one of the buildings and the server, all the cameras within that building will no longer be recorded or be able to be viewed live. In this example, all the video from these cameras will be lost.
Edge Recording:
In this example, you have a company office building and a manufacturing plant. The 2 buildings are found about one mile apart from each other. You've a dedicated T1 connection between the two locations. The T1 is used to share info transmission between the 2 sites. Almost all of the installed cameras will be at the producing plant so that company is able to monitor the plant remotely. The company office will have 4 to six cameras installed to view the main entrance and worker parking area.
For this example, edge recording offers the most cost effective solution for your company. Limited connectivity between the 2 locations is the largest hindrance. The standard IP camera requires about 2Mb per second available bandwidth. The first camera would consume all the available bandwidth of a T1 connection making centralized recording most unlikely. Edge recording doesn't forestall centralized viewing it only stops the recording of the camera centrally. For this example, you would use two network video recorders. You would scale each recorder to fit the amount of cameras they're going to be recording. From the client side or remote connection, you would be able to configure the system as though it were a single connection. The sole difference would be the refresh speed of the remote cameras. In this example, edge recording supplies the most cheap answer while still meeting the goals of your company. The downside, in this application, is the price of having 2 servers and slower live display rates of the cameras.
The Rule Summary:
By reading this, I'm hoping that you are able to see how IP video offers a very different design and new features that weren't possible or cost prohibitive with a conventional coaxial wire system. There are many other benefits when using IP video. The 3 mentioned above are only some of the benefits that IP video technology has provided to the safety industry..
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