Analog Signal vs. Digital Signal

Analog (analoug) can be defined as a signal that varies continuously over time rather than being sent and received in discrete intervals. The word "analog" implies an analogy between cause and effect, voltage in and voltage out, current in and current out, sound in and frequency out.

Analog Video Signals include:

  • RS170 Mono (EIA/CCIR)
  • Composite (NTSC/PAL)
  • S-video, SVHS, YC
  • RGB

Digital is a signal that is sent and received in discrete intervals.  It is a way of sending voice, video, or data that reconstructs the signals using binary codes (1s and 0s) for transmission through wire, fiber optic cable, video conference, or over air techniques.

Digital Video Signals include:

High Resolution

Camera resolution is measured in the number of TV Lines, the greater the number of TV Lines the more detail the camera is capable of transmitting. Camera resolution is usually measured by mega pixel. 1 Mega pixel (MP) means that there are one million pixels or one million tiny dots that can be one of various colors creating an image. The more mega pixels in an image, usually means a higher quality resolution.

Interlaced Scan versus Progressive Scan

Two common methods for “painting” a video image on an electronic display screen by scanning or displaying each line or row of pixels.

Interlaced Scan, used in traditional television systems, uses two fields to create a frame. One field contains all the odd lines in the image, the other contains all the even lines of the image, they are drawn alternatively.

Also known as non-interlaced scanning, progressive scan is a method for displaying, storing or transmitting moving images in which all the lines of each frame are drawn in sequence rather then alternating even and odd lines like Interlaced.

Monochrome Cameras (B/W) versus Color Cameras

Monochrome is the brightness (luma) portion of a video signal without the color information.  Monochrome is also known as "black and white", and is what used to predate the color television.

Monochrome Cameras typically have a higher image resolution than colour cameras. In low light conditions a monochrome camera will produce better results. In addition, Colour Cameras are not sensitive to Infrared Light.

Back Light Compensation

For the adjustment of exposure to prevent the subject from turning out too dark when light is coming from behind it. Many cameras are now equipped with a Smart Control which automatically adjust to the level of background light. This enables the camera to pick-up detail which would otherwise be missed.

1/2" or 1/3" Format

1/3" and 1/2" refers to the size of the imaging area of the CCD or CMOS sensor in the camera. Generally speaking the greater the sensor area, the higher the resolution of the camera. Although more recently high performance 1/3" CCD imagers have improved in resolution considerably.

Sensitivity

The sensitivity of a camera is typically expressed in either the number of photons or in a measure of photon flux which can be related to human observations. This sensitivity is measured by the minimum amount of light (lux) required to produce a picture. A Lux is a measure of illumination which has a value of 1 lumen per square meter. The Lumen is a photometric equivalent of a watt which is weighted to match the eye response of the "standard observer"

Choosing a more sensitive camera will improve picture clarity.

MAJOR INDUSTRIAL CAMERA MANUFACTURERS INCLUDE:

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