The purpose of a camera system is to enhance the safety and security of a facility and it employees. With this purpose in mind you need to decide the who, what, when, and where that the CCTV System will view and record. Next you must determine how long you would like to keep this information. Will a week suffice? Or do you need a month or two before a problem comes to light that you need to review? Do you need real time search of archived information? Will the system be constantly viewed or just reviewed when needed? What level of detail do you need, a face or a large general overview, or both?
A threat assessment and/or risk analysis should be done to determine your needs. Three basic steps are required to define your needs.
- Determine the types of threats that might occur. This should include threats to people, property, privacy and information.
- You must determine the likelihood of these threats.
- Last determine what the impact of each of these threats will have on your business and employees should they take place.
Key elements of your CCTV system should include a DVR (digital video recorder), a monitor(s), cameras, power supply(s), and wire type.
First, DVR's can handle 4, 8-9, 16, 24, or 32 camera inputs. Be sure to allow for growth in this area, as the DVR is the most expensive single item in a system. The hard drive size will determine the amount of days or months you can store video information. So, when calculating video storage keep in mind several factors. Will you need 24 hour continuous recording, motion based, scheduled, input triggered (ex. door contact), alarm or a combination? There are other factors that will affect video storage as well. The video resolution or CIF (adjustable on most DVRs), frame rate or frames per second, color v.s. black and white (color uses more space), audio recording, and POS (point of sale) integration. With these factors you can make a 160GB hard drive record for a few days or a month depending on setup. So, please read the fine print about how long you can get video recorded on the hard drive. The most common mistake I have seen is people don't get a large enough hard drive. Many DVRs can not be upgraded to a larger size. However, some can be expaned with internal or external hard drives. A few can use RAID storage expansion options. There are several DVR storage calculators available online to help you determine your needs. These types of DVRs are hardware based, not to be confused with PCs that have been modified to act like DVRs. The second most common mistake is DVR buyers do not get enough camera inputs. Only a few of the larger systems allow you to add more camera inputs, otherwise you will new a DVR with more inputs or a second DVR. Allow for growth in this area.
A NVR or Network Video Recorder records video and audio data streams received over Ethernet networks using the TCP/IP protocol. These are for use with Network cameras. NVR's with 64 cameras are not uncommon.There are a few hybrid systems available that have both Network and standard BNC connections. NVR's and IP Cameras are the next type of camera system that will replace even the DVR. You can even use a server to record your cameras. Unlike DVRs you are not as limited to adding cameras, you just need a new user license for the camera(s). Adding more memory is also easy with a well chosen NVR or server. An IP camera system also allows you to have cameras off site or at other locations and have a centerized recording location. All offer remote viewing.The IP/NVR solution has most of the weaknesses of a DVR taken care of. The only downside is recording cameras offsite relies on the DSL service. If this service goes out, you don't get any video.
Most DVRs allow for remote viewing off site or through the network. The two major types are through a web viewer or with supplied software. You will need high speed internet at the DVR and at your viewing location for these to work well. Some can be set up to email alarms or events to you as well. Others offer a PDA Client for viewing images and remote PTZ (pan/tilt/zoom camera) control. How you plan on keeping or archiving images is important as well. Almost all have a USB for loading small files to a USB storage device. You may want to consider upgrading to a CD or DVD burner if you need to keep evidence or make copies for police or insurance.
DVRs almost always have alarm inputs and relay outputs. These can be used with an alarm system to cause a high quality Panic recording of all cameras in the event the alarm is triggered. You can also cause a recording to be triggered by a Normally Open or Normally Closed contact, like a door, safe contact or motion detector. Some relay outputs can power a siren or strobe. With inputs and relays only your imagination is the limit.
The monitor is where you will view and review you video. The standard CCTV Monitor has BNC connections, the same as most professional DVRs. Other connections that you will see are VGA (computer), S-Video, and even composite (like your vcr or dvd at home). Monitor size is important. I recommend at least a 17" monitor for a four camera system. Anything less and the images are too small to see well. A 19" should be used for eight or more cameras. Also, many DVRs allow for a Spot Monitor output for a second monitor to be used with the Main Monitor. The Spot Monitor usually only allows for one camera to be viewed on-screen by sequencing through or by motion activity. Some spot monitors are programmable to be set up similar to the main monitor. You can view 4 cameras at once and sequence through the others if you like. Check out Pelco's DX4508250. If your monitor is to be watched on a regular basis go big, you won't regret it. You, may have seen mention of 9" monitors, these don't get used much any more with the used of DVRs. However, in a large rack system these are handy. 19" and 20" LCD prices are low enough to make the 9" go by way of the old vcr. One other use for your monitor not to be overlooked is the public view monitor. This type of monitor is set-up to be seen by the general public as a reminder and preventive tool. You may have seen these at your local wal-mart or other retail store. This is usually done through the Spot Monitor output or looped through the public view monitor before reaching the DVR.
After your DVR, the second most critical component of a CCTV System is the camera. There are several types and components that make up a camera. First, the lens. Lenses come in different sizes. The most common is 1/3-inch, but also 1/2-inch, 1/4-inch and smaller for "board cameras". The CS mount is also the most common connection for a lens to a camera. The lens allows you to focus on an area for view. A lens many include a fixed or auto iris. The auto iris will adjust to changing light conditions, you can usually spot it by the cord that plugs into the camera. Lenses are measured in millimeters. (ex. 3-9mm) A 3mm lens will have a wide view compared to a 50mm lens that is very close. Many lenses come in a varifocal style where the view can be adjusted to meet the needs onsite. This is handy if you are not familiar with what you may need. A 3-9mm is a great general use indoor or outdoor lens. The 3-9mm lens also has 3 times zoom. This is a fixed setting and not motorized or zoom capable. However, you can get motorized zoom lens that will require a controller. The PTZ combines this with a camera that can also move. Remember if you are going to buy day/night cameras you will also need day/night lenses. These usually have IR cut filters which can be removed. The single most important thing to remember about lenses is this is not an area to go cheap on. The lens quality can affect the clarity of the camera. Even if you have a multi-mega pixel camera, a cheap lens will get you a bad picture. The reverse is also true in most cases, an average camera can look very good with a high quality lens. It is just like your own eyes, you want 20/20 vision out of a lens.
The imager on a camera is what converts what the lens see to a digital or analog format. The most common is the CCD (charged coupling device) but Pixel Based Imagers are available now and not expensive. The Pixel Based Imager can adjust to changing light and light and dark areas better than the CCD. Only the small area affected by the light will change not the entire image, which can end up looking washed out or too dark with a CCD. An example would be in a store where light comes in from windows and changes the what the camera sees. Also good to use in an area like a warehouse with open bay doors. Cameras come with the ability for day/night (D/N) use, wide dynamic range (WDR), and night vision or thermal cameras. DN cameras would be generally for a parking lot, ect.. The WDR is a solution to the light problem like the Pixel Based Imager. A WDR can easily adust to a variety of light conditions and is a great indoor solution for bright areas. Thermal cameras are still very expensive (a few thousand each) but the cost is leveling out. A few specifications on a camera tell you a lot. Look for high signal-to-noise ratio, around 50dB or greater. LUX is about minimum illumination or also known as lumen per square meter. The main thing to remember is that the higher the F-number the amount of light let in to the camera goes down. Remember a smoked camera dome or cover will loss light and make the camera darker. A clear dome will have zero light loss and a smoked dome will usually have about 1.5 F-stop light loss. The horizontal resolution of a camera should be 480 to 540+ TV lines. IP cameras have already far surpassed the 540+ resolution limit. Last look for UL Listed items.
IP cameras are a whole different ball game compared to the common style camera. IP cameras can have very high resolution up into multiple mega pixels. Plan on a very large hard drive if you want to record video from mega pixel IP cameras. IP cameras will use the network to transmit video so make sure your IT department understands how much bandwidth they will use. IP cameras are a good choice if you have a network in place and are looking to save on cabling cost. Even small locations can take advantage of IP cameras and network systems.
There are several styles of camera housings. Domes, fixed, PTZ, board (spy), wall mount, corner mount, in ceiling and track styles to name a few. Each has its use and place. Some can be mounted flush, on walls, on or in ceilings, poles, basically anywhere with the right adapter or mount. You can get plastic, vandal proof, high security, explosion proof, or environmentally sealed for extreme conditions like corrosive or oxidizing chemicals (NEMA 4). Some can even take a 9mm round or shotgun blast. Hopefully your workplace is not that bad.
Now you must power all your new cameras. Your cameras will tell you what kind of power they require. This is usually 12, 24 or 110/220 Volts. 12 Volts is ok for wire runs of less than 100ft. If a 12 volt power supply is used it is recommended that the cameras be powered from a supply specifically designed for multiple cameras. This insures they all have the same ground reference. A 24 Volt system can go out to about 750ft or more with the correct wire size. A 24 volt system is what we normally use. I like Altronix power supplies, American made and lifetime warranty. Some 24 volt power supplies can be switched to 28 volts. Most CCTV cameras, heaters, and accessories are 24 volts. 110/220 Volt is another choice for camera power, but will require an electrician to get power where it is needed. The draw back of 110/220 is for possible ground loop problems and lightning strikes. POE or power over ethernet is a new option available for powering cameras. The standard has not been set for how much power this will provide, but it looks like 30 volts will replace the 15. This is so PTZ cameras can be powered using the Cat5 cableing as well. It is recommended that no matter what power you opt for you should use surge and lightning suppression. I recommended that you use an uninterruptable power supply (UPS) or a backup generator in the event of a power failure. A multiple output power supply will make this easier to set-up.
The wire that you use can affect you CCTV system. 22 AWG wire is the smallest to consider. Most common is 18 AWG or ever 16 AWG for 24 Volt systems. Your video can also be affected by wire type. RG/59 is the most common. I personally prefer RG/6, which gives you a larger center conductor. Others include RG/175 and RG/11. This type of cable is 75-ohm cable with mostly copper. Other similar cables are not interchangeable with CCTV cabling. For example, CATV is identical except that the center conductor and shield are aluminum. This will cause poor picture quality and in some instances no picture. These types of cables use a Bayonet-Neil-Concelman connector (BNC) to connect to the equipment. There are two basic types: Twist-on and Crimp/Solder. The ladder provides the best connection. One thing to remember is make sure you have a clean connection at the BNC and you do not have exposed copper shielding sticking out. This would cause a poor picture over time. A second option becoming more popular for video is UTP or Unshielded Twisted Pair. These include CAT5, CAT5E, and CAT6. This type uses two pairs of twisted wire to transmit video. Some cameras include UTP connections, however adapters are available for a small cost. This is a very cost effective way for long multiple wire runs going in the same general direction. There are two types: passive and active. Passive has a distance upto 750 ft' or more. An Active can transmit video up to 3 miles with the proper transmitter and receivers. IP Cameras can also use network type cable but in a different way. They plug in like computers and require a network and an IP Address.
Other alternatives are Fiber Optic cable and Wireless. Most wireless systems for professional CCTV tend to be line-of-sight for transmitting over great distances or for building to building. I've used some that can go 12+ miles with line-of-sight. For professional CCTV they tend to be expensive and you would need to consult a profession for their use. .
. Please consult a locally licensed CCTV professional if you have more questions. If you are considering someone to install your equipment for you make sure they are a dealer for the manufacture or have the ability to access tech support for the manufacture(s) whose equipment you purchased and have access to repair your equipment. Make sure the installing company is licensed for your state. Check out NBFAA for members or your state alarm association (Ex. Alabama Alarm Assocation).
last updated on: 04/08/2008