Traditional Analogue  CCTV.

Please note if you have an old analogue CCTV system and need a replacement camera or DVR then our AHD range of cameras and DVRS can be used. If in doubt what type of CCTV you have then please call 01748 811991 for advice.

Composite Video (CBVS)

Up until a few years ago there was mainly only one signal format used in CCTV, this was composite video or CBVS. Composite video is an analogue signal.  CCTV cameras used in the main CCD (Close couple device) image sensing chips to capture the CCTV video. There were some CCTV cameras that used CMOS image sensors but these were generally of very poor quality. Because the digital signal captured by the CCTV cameras was converted to an analogue PAL composite video signal the resolution of the camera was usually referred to in TVL (Television lines). Early models were only about 350TVL and the very latest Sony Effio CCD based cameras are 700TVL.

In the early days VCRs were used for recording CCTV images. VCRs were only capable of recording at about 225TVL. So the image output of the camera was significantly higher than the VCR could record. When DVRs (Digital video recorders) came to the industry they recorded at CIF resolution which is about 275TVL. A bit better than a VCR, but not significant. The main advantage DVRs brought was that they could record at much higher frame rates than a VCR. In the early 2000`s the D1 recording standard was introduced to DVRs, this had a TVL equivalent of about 600TVL. D1 was the generally the best recording standard available in the CCTV industry until about 2 years ago when 960H DVRs were introduced. These had a recording resolution of about 700TVL and they matched the output of the best CCTV cameras.

CCTV camera and DVR performance are now measured in pixels i.e the number of dots that make up the image. The more pixels the better image quality you will get. So if you are looking for CCTV equipment now look at the DVRs recording quality in pixels and again the cameras video output in pixels rather than TVL.

A 700TVL camera is 960 x 756 pixels and a 960H DVR is also 960 x 756 pixels. The total number of pixels is therefore 552960 or just over ½ a mega pixel.

Advantages.

1)      Will work with RG59 coax cable, CAT5 cable and CCTV baluns, Ready made of the shelf camera cable kits.

2)      Can have long cable runs, say 200m on RG59 coax, 300m on CAT5 cable and upto 1000m using CAT5 cable with active baluns.

3)      Cheap 960H DVRS start about £100 for a 4 channel DVR with a 500GB hard drive and 700TVL CCD cameras can be bought for about £30.00 each.

4)      When bought as a kit with ready made cables they are very easy to install.

5)      Can be easily set up to be viewed over the internet or on a mobile device.

6)      Fairly robust tried and tested technology which when purchased from a reputable supplier/manufacturer should give many years of reliable service.

Disadvantages.

1)      Relatively very poor image quality compared to HD-SDI CCTV or other mega pixel CCTV formats.

2)      Prone to induction interference from mains electrical cables or equipment.

3)      I do not believe it will be manufactured much longer and hence replacement camera and DVRs may not be available should you need to replace one to keep your system working.

Be very careful when buying CCTV, you will see a lot of the above equipment being sold as HD (Hi definition) but it is not!