CCTV

From Light to Pixels

Vlado Damjanovski

• Publisher: Butterworth-Heinemann
• Year: 2013
• ISBN:
  9780124046078
• Edition: 3
• Topic: Informatique
• Subtopic: Vision par ordinateur et reconnaissance de formes

The new edition of CCTV, a high-level professional reference, is expanded to cover all video compression techniques used in the ever-increasing assortment of digital video recorders (DVRs) available on the market today. In addition to demystifying DVR technology, the third edition also clarifies the technology of data networking and explains various compression techniques. Along with all this, the book retains the particulars that made the previous editions convenient and valuable, including details of CCD cameras, lenses, coaxial cables, fiber-optics, and system design.

• Updated to address digital techniques, networking, and the Internet in closed-circuit television
• Includes brand new sections on CCTV networking, digital video recorders (DVRs), various video compression techniques, and understanding pixels and digital image quality
• Fully illustrated with dozens of photographs, tables, checklists, charts, diagrams, and instructions

1

SI Units of Measurement

Abstract

The Laws of Physics are expressions of fundamental relationships between certain physical quantities. Measurements are made by comparing the magnitude of a quantity with that of a given unit of that quantity. In physics, which Electronics and Television are a part of, the International system of units, known as SI (from the French SystèmeInternationale), is used.

Key Words

basic unit; derived unit; International system of units; metric prefix

The basic units

The laws of physics are expressions of fundamental relationships between certain physical quantities.

There are many different quantities in physics. In order to simplify measurement and to comply with the theory of physics, some of them are taken as basic quantities, while all others are derived from those basic ones.

Measurements are made by comparing the magnitude of a quantity with that of a given unit of that quantity.

In physics, of which electronics and television are a part, the International System of Units, known as SI (from the French Système Internationale), is used.

The following are the seven basic units:

Unit	Symbol	Measures
Meter	[m]	length
Kilogram	[kg]	mass
Second	[s]	time
Ampere	[A]	electric current
Kelvin	[K]	temperature
Candela	[cd]	luminous intensity
Mole	[mol]	amount of substance

These basic units are defined by internationally recognized standards.

The standard for meter, for example, was defined as a certain number of wavelengths of a specific radiation in the spectrum of krypton until 1983. In October 1983 it was redefined as the distance that light travels in vacuum during a time of 1/299,792,458 second.

The standard of kilogram, for example, is the mass of a particular piece of platinum-iridium alloy cylinder kept at the International Bureau of Weights and Measurements in Sèvres, France.

The basic unit of time, the second, was defined in 1967, as a “time required for a Cesium-133 atom to undergo 9,192,631,770 vibrations.”

Kelvin degrees have the same scale division as Celsius degrees, only that the starting point of 0° K is equivalent to − 273° C; this is called the absolute zero.

All other units in physics are defined with some combination of the above-mentioned basic units. For example, an area of a block of land is defined by the equation:

where a is the width of the block of land, and b is the length. If both a and b are expressed in meters [m], the product P will be expressed in [m²]. We should mention that in mathematics the multiplication is not always represented with the × sign as above, but very often a dot • is used in between the factors being multiplied, or sometimes even without a symbol at all.

We all know that speed, for example, is defined as [m/s], although we quite often use [km/h]. We can easily convert [km/h] into [m/s] by knowing ...