CCTV - Do It Yourself Tutorial  part II

Manufacturers use usually few values to describe camera. The most important are: - resolution (380 TV lines is a standard, ultra high starts from 480 TVL) - LUX rating, amount of light needed for camera to work properly. 1 LUX equals light produced by one candle. Today’s cameras are rated usually below 1 LUX. 0.01 LUX means basically Day & Night camera, Infrared Cameras need no light at all since they are produce infrared beam, so they rated 0.0 LUX. - Lens. Usually surveillance cameras use wide lenses 2.5mm and up. Very popular 3.6mm lens would give you about 70 degrees field of view(FOV) horizontally and 57 degrees vertically. 6mm lens would give you about 48 degrees FOV horizontally and 37 degrees FOV vertically (for 1/3” CCD sensor). More mm means smaller FOV. Telephoto lenses are 20mm and up. - CCD sensor size (usually ¼” or 1/3”). The smaller the size, the smaller FOV. Simply 1/3” CCD sensor see more with same lens than ¼” CCD sensor.

There are few other values like backlight compensation, auto iris, auto white balance etc. There is many cameras on the market. Even if technical specs are same, you can see the difference comparing them side by side. We make sure all our cameras are the highest quality. We test weekly tens of cameras and usually only few of them qualify to be offered to our customers. Now let’s focus on DVR unit. Today nobody uses VCR’s anymore. All modern CCTV systems are based on DVR. DVR is a time lapse video recording device, multi-channel multiplexer and web server.

All in one. All our DVR units have following features: - multi channel capability (can support many cameras) - triplex function (record, playback and remote access, all can be done at the same time) - recycle function (it overwrites oldest data with the newest keeping always last few weeks of video) - motion activated recording (it records only when motion is detected and only from camera(s) that are detecting motion at that time) - recording on schedule (weekly schedule of recording for each camera can be set) - remote playback, viewer and control (DVR can be control and live picture can bee seen over the internet) - video backup (if you need to save some of the video)

Most important values used by manufacturers: - number of channels ( maximum number of cameras that can be plugged in to the DVR) - Maximum FPS (frames per second) DVR can record. It is total number for all channels. It can be different for recording and for display. Let’s say 4 CH DVR 120 FPS recording/display. This means 4 camera DVR can display and record with rate of 120 FPS. If you divide 120FPS by 4 cameras you will get 30FPS. So each camera can display 30FPS and can record 30FPS (30FPS is also known as “Real Time”). But lets take 4CH 30FPS DVR. If you use only one camera you can get maximum real time recording and display. If you use all 4 camera it will give you 7.5 FPS for each camera. But remember, you can change it, you can set one camera for example to record with 15FPS and the rest of the cameras to record with 5FPS. The total number of frames multiplied by number of cameras can not exceed maximum FPS for particular DVR. 98% of surveillance DVR do not record with more than 3-5FPS. There is no reason to record video with higher FPS rate. It also saves you a lot of space. Remember, real time recording consumes a lot of memory. It’s not practical. So if you let’s say getting 16CH DVR and you will actually use all 16CH, 120FPS will be enough in most cases. This will give you 7.5 FPS for each camera which is more than enough even for watching your cash register.

Real time recording is used only in extreme situations (very fast moving objects, casinos (card tables)). - Storage space in GB (standalone and PC based DVR’s usually come with hard drive built in, but you can always add extra one. DVR boards use hard drive of your computer, good practice is to have separate hard drive just for DVR). Our DVR boards work fine with 95% of today’s computers. Sometimes graphic card upgrade is required. They also do not need dedicated PC. You can simply let the system run in the background. You will not even notice the difference in performance of your PC. Of course having dedicated PC is recommended especially for large systems. We prefer PC based DVR’s. Simply because they are more user friendly, software updates are available, have more features and can be easily customized. But if you don’t want to have another PC you can always use simple standalone DVR’s. They are usually very dependable and have all basic features to run your surveillance system. Remeber, basic CCTV system includes: - Cameras - DVR unit - Cables (one for each camera when using Plug&Play cables, or coaxial RG59 and low voltage 22/2 (or Siamese) when you have really long runs 300ft and more) - Power supply (one for each camera when using single power adaptors, or multi-channel power distribution box) - Monitor (regular TV when using standalone DVR, PC monitor when using PC based systems) Optional - Internet router and internet access (when you want to be able to access your system via internet) This is some basic knowledge required to start shopping for surveillance system. If you need more information, call or email us. Thank you and good luck.