Security Surveillance Systems Performance Factors

Security Surveillance Systems Performance Factors


Any Security Surveillance Systems starts with CCTV security cameras. The images you see and record can only be as good as the images produced by your CCTV security cameras whether they are mini cameras or network cameras. Good security cameras produce good images.There are several critical specification factors which affect the performance of your security cameras and consequently, the quality of your camera images. These factors also affect the price of security cameras. We offer a selection of CCTV security cameras to meet almost any situational need and budget. All our security cameras provide excellent specification factors, overall quality and excellent video images, coupled with very competitive prices.


The main performance factors are:

The Type and Quality of the Imaging Chip in the camera:

CCTV security cameras produce images using CMOS or CCD (Charge Couple Device) chips. Tiny and/or very low price CCTV cameras usually use CMOS technology, produce poor quality video and have very poor light sensitivity. Decent quality and better CCTV cameras use CCD technology.

The Make of the CCD chip in the camera:

Not all CCD chips are equal, even with the same specifications. Quality varies by manufacturer. Sony and Panasonic are generally recognized as producers of the best CCD chips. Most CCTV security cameras supplied by Sentry Security Systems use CCD chips from these two manufacturers.

The Type of DSP (Digital Signal Processing) Chip in the camera:

Digital CCTV security cameras use a DSP chip to digitize the analog video stream produced by the CCD chip, in order to improve certain picture quality elements and to add additional functionality. The DSP chip in the camera can have a very large effect on the quality of the video images produced by the camera. All CCTV security cameras supplied by Sentry Security Systems Inc. use DSP chips.

Number of TV Lines:

The number of TV lines in the video produced by the security camera is a measure of picture resolution (sharpness). The larger the number of TV lines, the better the resolution and hence, overall picture quality. Over 370 TV Lines is generally considered good resolution while over 450 TV lines is considered high resolution. All our CCTV cameras have a resolution of at least 380 TV lines with many well over 400 TV Lines.

Light Sensitivity:

Sensitivity ratings are generally given as the minimum "Lux" levels at which the camera will produce a useable image (1 Lux equals 1/10 Foot Candle). The lower the Lux number, the lower the light levels at which the CCTV camera will produce an acceptable image. In other words, the lower the Lux level rating, the more light sensitive the camera.

Signal to Noise (S/N) Ratio: The higher the Signal to Noise ratio, the clearer the video image produced by the camera. Good CCTV cameras will have a S/N ratio of at least 48dB. Our Mintron color cameras have an actual S/N ratio of 60dB - much better than most while our Sentry cameras have S/N ratios of at least 50dB.


Camera Types:

Fixed (non moveable)

CCTV security cameras come in two main styles: The first style has a camera body, to which lenses of different focal lengths and/or fixed or variable irises may be attached.

The second style is basically a fixed lens mounted on a camera circuit board (board camera). These cameras may be packaged in a small case (Mini Cameras) or dome (Mini Dome) or tube (Bullet, Lipstick or Tube) or simply sold unpackaged, for mounting by the purchaser. Lenses in these cameras are either of a normal industry aperture or a "pinhole" lens of very small aperture. Pinhole lens cameras are often called "spy" cameras and may be mounted in a concealed way for covert surveillance purposes. Since the lenses in board cameras are pre-mounted, have a fixed iris and are usually of a short focal length (i.e. wide angle), their flexibility of usefulness is limited. However, this type of camera can provide a low cost solution in the right situation, particularly in a home or retail environment.

Pan, Tilt, Zoom (PTZ) Security Cameras:

PTZ security cameras are able to rotate horizontally through 360, vertically through 90 and have electrically powered zoom lenses capable of giving better than fifteen times optical zoom. Movement can be very fast and is controlled through a connected controller and/or through an appropriate DVR. In addition, PTZ cameras can be set to auto-scan or to move through a pre-defined range of pre-set positions and amounts of zoom.

PTZ security cameras are normally mounted in domes and when used outside, the domes are weatherproof and thermostatically cooled and heated. Vandal resistant domes are also available.

Once used almost exclusively by large corporations, governments and casinos, Pan, Tilt, Zoom (PTZ) CCTV cameras have now become much more affordable and offer better performance than just a few years ago.