CCTV CAMERA

CCTV is the abbreviation of closed circuit television camera. 
 is the use of video camera to transmit a signal to a specific place, on a limited set of monitors. It differs from broadcast television in that the signal is not openly transmitted, though it may employ point to point (P2P), point to multipoint, or mesh wireless links. Though almost all video cameras fit this definition, the term is most often applied to those used for surveillance in areas that may need monitoring such as banks, casinos, airports, military installations, and convenience stores video telephony is seldom called "CCTV" but the use of video in distance education, where it is an important tool, is often so called.
INSTALLATION:

Planning:
First step of any camera installation is to plan camera and monitoring equipment locations. When planning for camera locations please take in consideration light condition, never install cameras in low light room pointing straight into the sunny area it will add glare to the picture, even if your camera has back light compensation it will not be enough. Use infrared cameras for very dark conditions and/or B/W cameras with as low LUX number as possible. I am not going to discuss proper equipment selection, as this was subject of my previous article. You can read it at www.amazingcameras.com or www.dvrexperts.com .
Selecting the best possible camera locations is not easy, and will directly impact the camera views. Besides light conditions, the distance to the monitoring object is equally important. There are many different types and focal lengths of lenses; your selection will depend on light condition and distance from the camera to the monitoring object. In small rooms around 500sq. ft. cameras with standard 3.6mm lens should be OK. Keep in mind that most bullet and board type of cameras come with 3.6mm lens, the greater the distance to the monitoring object the longer focal length of the lens will be needed. There is no ease way of judging lens selection, you can either guess or buy professional lens selector tool available at www.dvrexperts.com. Alternatively you can start with your lens selection and if needed get longer or shorter focal length lens later. Other option as far as lens selection goes, is to use varifocal lens, which is very versatile approach and takes the guess out of the lens selection process. For those who do not know what varifocal lens is, it’s basically adjustable focal length lens that will allow to change the focal length within specified range, fore example: 2.6mm – 8mm or 5mm - 50mm etc.
To maximize cameras coverage and get the most out of the CCTV system for least amount of money minimize number of cameras by placing cameras in strategic places, unless complete area coverage is needed. Avoid overlapping camera views, do not install cameras with source of light directly in front of it and do not place infrared cameras pointing at each other to eliminate risk of overexposure. These are the most common mistakes that need to be avoided.
After the initial camera locations are predetermined, lets look at cable placement. Make sure that it is actually possible and practical to run cable to each camera location, if running the cable to any camera location is for some reason impossible opt out for alternate camera location.

Wiring:
The most time consuming and important part of any camera installation is wiring.
Plan your installation carefully to minimize cable lengths and insure good quality video signal.
Never run cables alongside high power electrical lines, at least 12” spacing between video cable and power lines are recommended.
Keep the cable lengths below 400ft and use good quality cable, most people take the cable for granted, but it is actually very important aspect of any installation. 
The CCTV system is only as good as its weakest component.
I usually stick with RG59U with power Coleman cable (YES it is US made) sometimes called Siamese type cable. It is combo cable and will transmit video and power, as an alternative it is sometimes possible to use less expensive RG6 standard coax cable with separate run of 18/2AWG for power. The Siamese cable is less bulky and easer to run, distribution power supply is recommended with this type of cable as power will be supplied from common place right next to monitor and recording equipment. Using Siamese cable makes for more clean and neat installation, as only one line is required for each camera. Running RG6 cable with separate run for power is the likely solution if power outlets are available near each camera locations. In this case individual plug in power supplies are used to power the cameras with power cable running as separate and independent line to the camera. Both types of cables are available at www.dvrexperts.com. 
When running the cable it is good practice to leave couple of loops of extra cable at both camera and monitoring locations. This extra length of cable is needed if in the future monitoring or camera location will have to be moved slightly. 
After the cable is in place, the labor-intensive part of installation is over, now we can get to the fun part of installation.

Camera mounting:
Most cameras come with mounting screws and bracket included, attach the bracket firmly and remember that in some cases different brackets than the ones supplied with the cameras mite be needed, for example drop sealing installation will require T-Rail camera bracket like the one available at www.dvrexperts.com.
Attach the camera to the bracket and adjust the camera position approximately at this time, we will come back to it later. Typical security camera is powered by 12VDC or 24VAC and power input type is screw or push terminals or 2.1mm plug. Power connection will differ for each type of power supply and input style. Most cameras are 12VDC, in this case it is important to observe polarity or you may damage the camera. The power cable has two conductors and in most cases it will be red or white and black cable. Use the red or white for positive and black for negative terminals. If your camera has screw or push terminals power input connect the cable directly observing polarity, if it is 2.1mm plug, a special 2.1MM Female DC Plug with Flying Leads have to be connected to the cable again keep attention to polarity. You may get the power plug from www.dvrexperts.com. The 24VAC connection is very similar, with one major difference - polarity is not important.
Next step will involve some special tools and accessories.
We will attempt to go over installation process of BNC crimp-on video connector, I will post video demonstration of BNC crimping techniques shortly so please check the web sites mentioned in this article often. 
Steps:
1. Remove about 1/2-inch long outer jacket from the end of video cable exposing braid.
2. Slide the crimping barrel onto the cable with the larger diameter facing end of the cable.
3. Pull the braid backwards exposing the inner isolator material and remove 3/8-inch of it so you have now core conductor exposed.
4. The main part of BNC connector has a small hole on one side; push the exposed core conductor of the cable into that hole as far as it will go.
5. Push all the braid folded backwards in step 3 onto the BNC connector and spread the braid evenly around connector.
6. Push the crimping barrel onto the BNC connector all the way.
7. Using crimping tool, squeeze the crimping barrel onto the BNC connector, now the cable braid is compressed in between crimping barrel and BNC connector assuring secure connection.

BNC connector is on, lets hook it up now and repeat the steps for each camera, if you have purchased 16 camera system you may want to get some coffee first.

Monitor and recorder connection:
Cameras are on, its time to make final connections. I will focused on standard CCTV monitor, standalone DVR recorder and distribution power supply, as this is the most popular and likely solution for most CCTV installations.
First we have to install BNC connectors on this side as well - its time for that coffee again.
It is good idea to make room for monitor and recorder now and setup some type of desk, shelf or rack to place all the equipment on.
We need the monitor and recorder in place so we can determine proper power supply location. 
Power supply should be mounted within couple of feet from the DVR video inputs.
After power supply is secured separate the power conductors from the Siamese cable, and run it to power supply. Like we did with the cameras if 12VDC power is used, we need to watch the polarity, each terminal on the power supply is marked, so there should not be any doubt. Make sure the power supply is not plugged in to the power outlet yet.
Connect video cables to the DVR video in ports. We need one video cable to connect the DVR with the monitor, if you do not have one you may cut piece of Siamese cable separate the power conductors from it and install BNC connectors on both ends, you now have the cable.
Connect the DVR monitor out port to monitor video in.
We are almost ready to power up everything; there is only one more thing to take care before we do that.
We need to protect the equipment from power spikes by plugging it into power conditioner or better yet buttery backup unit. If the installation location is experiencing frequent power outages, the backup unit is strongly recommended. To extend the backup time only plug the DVR and camera power supply to the backup unit and the monitor to regular power strip, this way if we do loose power for some time the DVR and cameras are still functioning as normal while monitor is off. Turning off monitor will not affect DVR and cameras in any way; it is actually good habit to turn the monitor of if not used to extend its life.

Power on and final adjustment:
Yes… we are now ready to power it up for the first time, if this is your first installation it may be nerve-racking experience.
Start with turning the cameras power supply on; turn the monitor on as well followed by DVR system. The stand-alone DVR after self-test will show cameras or setup menu on first power up depending on your model.
To setup the DVR refer to the manual for proper settings.
Go over each camera view to determine if the camera view is actually what you want,
very rarely it will be the first time. To properly and easily adjust camera positions the test monitor will be very handy if not essential tool. Go to each camera location and connect the test monitor to adjust camera position to your preferences, if satisfied secure camera bracket adjustment screws - we will not go back to this camera anymore.

Basic Electronics Defination

According to oxford dictionary Electronics is


"The branch of physics and technology concerned with the design of circuits using transistors and microchips, and with the behaviour and movement of electrons in a semiconductor, conductor, vacuum, or gas:"

The basic electronics covers following topics
1. Atoms
2. Electrical Charges
3. Current
4. Voltage
5. Resistance
6. Inductance
7. Capacitance
8. Magnetism
9. Capacitor
10. Power
11. Ohm law
12. resistors


ATOMS
usually Atom is considered as smallest particle of an element. It consist on 
1. electron
2. proton
3. neutron

Electronics had negative charge on them which is equal to 1.6*10^-19 coulomb.
Proton had positive charge which is equal to the value of the charge as it is on electron.
Neutron are electrically neutral and does not pretend any electrical behaviour.

Number of electronics and protons in an atom is always equal which is also called the Atomic number.
While the number of proton decide the Atomic mass of atom in combination with protons. Means the number of protons+neutrans are known as Atomic Mass.


The protons and neutrons are present in the center of atoms forming what is called the nucleus and the electrons revolve around them.





ELECTRICAL CHARGES

It is important to remember that particles, which have same charge repel while unlike charges attract each other. Therefore a proton and electron will attract while a proton and proton will repel each other. In other words they will move away from each other. Electricity is the flow of electrons so it is necessary to measure the charge. The basic unit for measuring charge is the coulomb or the letter C.









1 columb charge is equal to the amount of 6.25*10^18 electrons.


 CURRENT

Current is caused due to motion of electrical charge - the flow of electrons in a circuit is called current.  Current is measured in AMPERES (AMPS, A or I).


 Electric current is the amount of electrons, or charge, moving past a point every second.
Therefore amount of flow of current depends upon flow (speed) of electrons

I=Q/T
 or
1 ampere = 1 coloumb / 1 sec

 Therefore for every amp, there are 6.25x10^18 electrons moving through a point every second or A flow of electrons forced into motion by voltage is known as current.


 VOLTAGE

Voltage is the electrical force or "pressure" that causes current to flow in a circuit. It is measured in VOLTS (V or E).
In other words, current can only flow only if voltage is applied between two terminals.
The difference between these two terminals is called the potential difference. The larger the potential difference, the larger the voltage.
Therefore, Voltage can be thought of as the measure of the pressure pushing the electrons.

One volt will cause 1 amp of current through 1 ohm of  resistance.


RESISTANCE

The opposition in the way of flow of current is called Resistance. This is the property of every material whether it is conductor, semiconductor or insulator. This property classify the materials in three groups because in conductor resistance is very low while in semiconductor it is inbetween of conductor and insulator, while in insulator this resistance is too high.

Resistance is denoted by R
its unit is ohm and represent as sign of omega

different values resistances are available in different forms of resistors to get the right potential difference across each of them.


INDUCTANCE

Inductance can be defined as ability of the coil of wire to resist any change in electric current passing through the coil.
According to faradays law, the inductance L may be defined in terms of the emf generated to oppose a given change in the current.
The value of an inductance is directly proportional to the number of turns wound or used.








CAPACITANCE


The number of electrons that can be stored under a given electrical pressure (voltage) is called its capacitance or capacity. The property of capacitance is exhibited by capacitor. Basically, a capacitor consists of two metallic plates separated by a non-conducting substance between them.

In the circuit shown left when the switch is open the capacitor is not charged i.e. it does not contain any charges but when the switch is closed current starts to flow and capacitor gets charged. This process of charging takes place because the emf forces electrons into the top plate of the capacitor from the negative end of the battery and pulls others out of the bottom plate toward the positive end of the battery.
The unit uF stands for microfarad (one millionth) and pF stands for Pico-farad (one million, millionths). These are the two common values of capacitance you will encounter in electronics.
Time constant of capacitanceThe time required for a capacitor to get completely charged depends upon two factors:
1. The capacitance value
2. The resistance value.
The time constant of a resistance - capacitance circuit is:
T = R X CWhere T = time in seconds
where R = resistance in ohms
where C = capacitance in farads


MAGNETISM

Magnetism is a phenomenon by which materials exert an attractive or repulsive force on other materials.
Unlike electric charges (such as those observed when amber is rubbed against cloth), magnetic objects possessed two poles of opposite effect, denoted "north" and "south" after their self-orientation to the earth.
Materials like iron, steel, and the mineral lodestone are influenced by the presence of a magnetic field.
Basically, a magnetic field arises due to the moving electric charges.

There are various types of magnets depending upon Orientation of Electric Charges.

Magnetic Poles 

• When a magnet is suspended freely, one side points North. This is called the North Pole of the magnet. The other side points South, and is called the South Pole of the magnet.
  
  A magnetic compass is used for finding north and South Pole.
  
  

Magnetic Fields

•  A magnet is surrounded by an invisible force field. Electric coils, currents in wires, and permanent magnets are all sources of magnetic field. Moving charged particles produces magnetic fields. In case of electromagnets, electron flow through a coil of wire connected to a battery; in permanent magnets, spinning electrons within the atoms produces the field. Lines of magnetic force can be seen around a magnet by sprinkling iron filings on to a sheet above it and tapping the sheet. The strength of the magnetic force is strongest close to the poles and gets weaker as you move away from the poles.
  
  

Magnetic Domains

• Normally the electrons are paired up and they cancel each others field; but in iron, some of the electrons are unpaired. Their spins tend to line up together, creating tiny pockets of magnetism called magnetic In the atoms of magnetic metals, the electrons spinning around the nucleus create a small magnetic field. domains.

Therefore, in magnetized material, magnetic domains are oriented towards one direction but in unmagnetised material, magnetic domains are randomly oriented in different directions.
Depending upon domains Magnets are classified in three categories, which are as follows

1. Permanent Magnets
2. Temporary Magnets
3. Electro Magnets

1. Permanent Magnets 

Permanent magnets are made from a ferromagnetic material, which at some point of time has been exposed, to a magnetic field. They are permanent in the sense that once they are magnetized, they retain a level of magnetism. Consider ferromagnetic material (one that can be magnetized without much effort), which can be made into a magnet by placing it in the centre of an electric coil or solenoid and passing a large current through the coil. If the material is magnetically `hard, it will retain its magnetism even when the current has been switched off. Permanent magnets are made from such hard materials as steel, nickel, and cobalt. Such magnetic alloys are used in electrical equipment and electronic devices

2. Temporary Magnets

Temporary magnets are those which act like a permanent magnet when they are within a strong magnetic field, but lose their magnetic property when the magnetic field disappears.
Examples: paperclips and nails and other soft iron items.

3. Electro Magnets

An electromagnet is a tightly wound helical coil of wire, usually with an iron core, which acts like a permanent magnet when current is flowing in the wire. The strength and polarity of the magnetic field produced by the electromagnet are adjustable by changing the magnitude of the current flowing through the wire and by changing the direction of the current flow.


CAPACITOR

A Capacitor is a passive electronic component that stores energy in the form of an electrostatic field.
Therefore Capacitors are used to store electric charge. Basically, a capacitor consists of two plates of a conducting material separated by a space filled by an insulator. The insulating layer is called the Dielectric of the capacitor.
Capacitance is directly proportional to the surface areas of the plates, and is inversely proportional to the plates separation.
The capacitor also functions as a filter, passing alternating current (AC), and blocking direct current (DC).
This symbol used to indicate a capacitor is -||-.
The fundamental property of a capacitor is that it can store charge and hence electric field energy. The capacitance C between two appropriate surfaces is defined by V=q\c where V is the potential difference between the surfaces and Q is the magnitude of the charge distributed on either surface
Capacitance is measured in units called
Farad: F
microfarad: µF (1 µF = 10-6 F)
nanofarad: nF (1 nF = 10-9 F)
picofarad: pF (1 pF = 10-12 F)

• Time constant of capacitance The time required for a capacitor to get charged is proportional to the capacitance value and the resistance value.
  
  The time constant of a resistance - capacitance circuit is:
  T = R X C Where T = time in seconds
  Where R = resistance in ohms
  Where C = capacitance in farads
  
  
• Capacitors in series and parallel When Capacitors are connected in parallel say C1,C2,C3,…….
  Add capacitor values together as C1 + C2 + C3 + ..... to get net capacitor value
  
  When capacitors are connected in series.
  The net value is calculated in following manner
  1 / (1 / C1 + 1 / C2 + 1 / C3 + .....)

POWER

Power is defined as the amount of energy used or the amount of "work" done by a circuit.
Power is represented by the letter P.
The basic unit for measuring power is watts or the letter W.

P=EI


OHMS LAW 

ohms law define the basic relationship of current, voltage, and resistance.

ohms law states that

"The amount of current flowing in a circuit is directly proportional to the electromotive forces impressed on the circuit and inversely proportional to the total resistance of the circuit."

According to the Ohms law, voltage equals current times resistance which is expressed in the following equation:
V=IR
where 
V = voltage,
I = current
R = resistance

RESISTORS
The resistors function is to oppose the flow of electric current. The most common schematic symbol for a resistor is a zigzag line shown in above diagram. An alternative schematic symbol for a resistor is a small and rectangular in shape Resistors are also classified according to the material from which they are made. The typical resistor is made of either carbon film or metal film. The value of resistor is determined by its colour. Black 1 Brown 2 Red 3 Orange 4 Yellow 5 Green 6 Blue 7 Violet 8 Gray 9 White 10 While selecting a resistor it is important to take value of tolerance and electric power rating of the resistor into consideration along with resistance value of the resistor. The tolerance of a resistor denotes how close it is to the actual rated resistance value. For example, a ±1% tolerance would indicate a resistor that is within ±1% of the specified resistance value, and the power rating indicates how much power the resistor can safely tolerate. The maximum rated power of the resistor is specified in Watts. Colour tolerance Brown (+or-)1% Red (+or-)2% Gold (+or-)5% Silver (+or-)10% There are two kinds of resistors namely fixed resistors and the variable resistors. Fixed ResistorsA fixed resistor is one in which the value of its resistance cannot change. Carbon film ResistorsThis is the most general purpose, cheap resistor. Usually the tolerance of the resistance value is ±5%. Power ratings of 1/8W, 1/4W and 1/2W are frequently used. Carbon film resistors have a disadvantage; they tend to be electrically noisy. Metal film resistors are recommended for use in analog circuits. Metal film ResistorsMetal film resistors are used when a higher tolerance (more accurate value) is needed. They are much more accurate in value than carbon film resistors. They have about ±0.05% tolerance. They have about ±0.05% tolerance. Resistors that are about ±1% are more than sufficient. Ni-Cr (Nichrome) seems to be used for the material of resistor. The metal film resistor is used for bridge circuits, filter circuits, and low-noise analog signal circuits. Variable ResistorsThere are two general ways in which variable resistors are used. Adjustment of one of the resistor is such that its value can be easily changed, like the volume adjustment of Radio while adjustment of Semi-fixed resistors are done to compensate for the inaccuracies in the resistors, and to fine-tune a circuit. The rotation angle of the variable resistor is usually about 300 degrees. At certain situation, variable resistors must be rotated according to get the whole range of resistance they offer. This allows for very precise adjustments of their value. These are called "Potentiometers" or "Trimmer Potentiometers." Other ResistorsThere is another type of resistor besides the carbon-film type and the metal film resistors. It is called wirewound resistor. A wirewound resistor is made of metal resistance wire, which helps to give them precise values. Also, using a thick wire material can make high-wattage resistors. Wirewound resistors cannot be used for high-frequency circuits as Coils are used in high frequency circuits. Another type of resistor is the Ceramic resistor. These are wirewound resistors in a ceramic case, strengthened with special cement having very high power ratings, from 1 or 2 watts to dozens of watts. While designing or making these resistors, it is necessary to take its heat withstanding ability into account as these devices can easily get hot enough to burn.