Friday, June 27, 2014

Satellite

Satellite : A satellite is one which orbits something, Moon orbits earth hence it is satellite.More specifically in communication a satellite is a wireless devices that orbits round the earth and capable of receiving and transmitting signals which is lunched with the help of rocket.There are hundreds of satellite orbiting the earth for different purposes like weather broadcasting,television broadcasting,Internet , military communication and general positioning system (GPS).

Here you can find the list of active geostationary satellite revolving the earth.

Download

Types of Broadcasting and Frequency Ranges.



Broadcasting (In Communication) refers to transmission of information (message signal)audio and video and text electronically to large number of audience through radio wave, wires or communication satellites and then to received it by the television set or radio receivers module (demodulator )
Types of broadcast system:
1. Teletext: This is the system that adds the data in to the blanking interval of an analog television signal. It has been developed in the 1970’s to relay information like weather, news and television programmed guides.

2. AM broadcasting: Amplitude Modulation or AM refers to long, medium and shortwaves signal that can travel across the earth for worldwide broadcast services.
3. Analog FM Broadcasting: Another audio broadcast system that delivers much better quality compared to AM radio.

4. Digital Broadcast system: Digitalizing of the radio and television broadcasting network had become a milestone. In the broadcasting world. Digital Radio Mondale (DRM) and digital audio Broadcasting system are just few examples. This can’t only improve audio and visual services but also enable multimedia services and navigation and monitoring roads through the use of satellite and terrestrial signals.
Before we go to satellite Broadcasting Let us go through Radio Frequency and its allocation the is a standard term according to higher and lower frequency range.

L Band (1-2 GHz): Global Positioning system carriers and also satellites, mobiles phones such as iridium, Inmarsat providing communication at sea, land and air world space satellite radio.

S-Band (2-4 GHz): Weather radar, surface ship radar, and some communication satellites, especially those of NASA for communication with ISS and space shuttle. In May 2009, Inmarsat and Solaris mobile (a joint venture between Eutelsat and Astra) were awarded each a2*15 MHz portion of the s-band by the European commission.

C Band (4-8 MHz): Primarily used for satellite communication for full time satellite TV Networks or raw satellite feeds. Commonly used in area that are subject to tropical rainfall, since it is less susceptible to rain fade than Ku band.

X –Band (8-12MHz): Primarily used by military. Used in radar application including continuous wave pulsed, single-polarization, dual-polarization-band radar frequency sub bands are used in Civil, military and government institution for weather monitoring, air traffic control maritime vessel traffic control, defense tracking and vehicle speed.

Ku Band (12-18 GHz): Use for satellite communication especially for DTH on some part for the down link 10.7 GHz to 12.75 GHz for direct broadcast satellite service.

Ka Band (26-40 GHz): Communication satellites, up-link in both 27.5GHz and 31 GHz band, and high resolution close range targeting on military crafting.

Tuesday, June 24, 2014

Skype Security

In an office or to others computer, when you share same network there is chances of someone may see your chat history when you go offline,so always remember to clear your chat history.when someone know the username of your computer,they even can access to your chat history if not cleared. How they can do?with third party software like skypelog viewer.Here are the steps how one can see your chat history without knowing your skype password,simply accecing your computer.
1.download third party software like skypelog viwer you can download from here
http://www.nirsoft.net/utils/skypelogview.zip
2.extract file and place it to your desktop.
3.Go to your C Drive programs and files
4.Go to your users folder.
5.Go to users name of your computer ,i.e if your username is dany then go to dany folder.
6.Go to AppData folder.
7.Go to Roaming folder.
8.Go to Skype folder.
9.Then go to the folder which name is username of skype ID.
10.Then go to main.db icon
11.Open it with the file that contain folder of SkypeLog view.
12.Remember to give the destination of folder which have same skype ID.

List of connector used in Broadcast



F- Connector:

The F connector is a coaxial RF connector commonly used for "over the air" terrestrial television, cable television and universally for satellite television and cable modems, usually with RG-6/U cable or, in older installations, with RG-59/U cable.
The F connector is inexpensive, yet has good 75 Ω impedance match up to 1 GHz and has usable bandwidth up to several GHz.

 

 

 

 

BNC

The BNC (Bayonet Neill Concelman) connector is a very common type of RF connector used for terminating coaxial cable.




 

 

 

 

 

RCA


RCA Plugs for composite video (yellow) and stereo audio (white and red)
RCA connectors, also known as phono connectors or phono plugs, are used for analog or digital audio or analog video, the RCA plug was also used for analog composite video and non-critical radio-frequency applications.

    Sometimes called a phono connector or cinch connector
    Used to carry audio and video signals
    sometimes casually referred to as A/V jacks
   The name "RCA" derives from the Radio Corporation of America,
    when connecting the male into the female, the inner 'hot' (signal) connection is made before the 'cold' (ground) connection has been guaranteed. This often produces a loud buzz, and could possibly harm some equipment
    They are often color-coded, yellow for composite video, red for the right channel, and white or black for the left channel of stereo audio.
    as a power connector, an RF connector, and as a connector for loudspeaker cables. Its use as a connector for composite video signals is extremely common, but provides poor impedance matching. RCA connectors and cable are also commonly used to carry S/PDIF-formatted digital audio, with plugs colored orange to differentiate them from other typical connections.


SDI :



The various serial digital interface standards all use (one or more) coaxial cables with BNC connectors, with a nominal impedance of 75 ohms.
Serial digital interface (SDI) is a family of digital video interfaces first standardized by SMPTE (The Society of Motion Picture and Television Engineers) in 1989.



HDMI
(High-Definition Multimedia Interface)
High-Definition Multimedia Interface (HDMI) is a compact audio/video standard for transmitting uncompressed digital data.











Composite Video:

Composite video (1 channel) is an analog video transmission (no audio) that carries standard definition video typically at 480i or 576iresolution. Video information is encoded on one channel in contrast with slightly higher quality S-video (2 channel), and even higher quality component video (3 or more channels).
Composite video is usually in standard formats such as NTSC, PAL, and SECAM and is often designated by the CVBS initialism, for color, video, blanking, and sync, or simply as video.

 DIN
 

·         A DIN connector is a connector that was originally standardized by the Deutsches Institut für Normung (DIN).
DIN 41524, for circular connectors often used for audio signals
·         DIN 41612, rectangular connectors used to connect plug-in cards to a back plane or motherboard
·         DIN 41652 D-subminiature connectors used for computer data and video



 N Connector:
 

The N connector (in full, Type N connector) is a threaded, weatherproof, medium-size RF connector used to join coaxial cables. It was one of the first connectors capable of carrying microwave-frequency signals


GR Connector:


The GR connector, officially the General Radio Type 874, was a type of RF connector used for connecting coaxial cable. Designed by theGeneral Radio Corporation, it was widely used on their electronic test equipment throughout the 60s and 70s.
The connector had several desirable properties:
·         Good control of the electrical impedance across a wide range of frequencies
·         Reliable mating
·         Hermaphrodism, so there were no "male" or "female" connectors; any GR connector could mate with any other GR connector.


C- Connector:


The C connector is a type of RF connector used for terminating coaxial cable. Coupling uses two-stud bayonet-type locks. The C connector was invented by Amphenol engineer Carl Concelman. It is weatherproof without being overly bulky.





TV Aerial Plug:



Domestic antenna plugs and sockets are devices that connect TV antenna (aerial) cable to a TV set.
Antenna plugs are male antenna connectors that fit into female antenna sockets.
The Belling-Lee connector or IEC 169-2 connector, known colloquially as TV aerial plug, TV antenna connector or simply an antenna plug, is the traditional RF connector for European TV sets and FM / DAB-radio receivers that connects them to a terrestrial VHF/UHF roof antenna, antenna amplifier, or CATV network via a coaxial cable. It is the oldest coaxial connector still commonly used in consumer devices.


Banana Connector:

A banana connector (commonly banana plug for the male, banana socket or banana jack for the female) is a single-wire (one conductor) electrical connector used for joining wires to equipment.


CVBS = "Color, Video, Blank and Sync"







DVI:



Digital Visual Interface (DVI) is a video display interface developed by the Digital Display Working Group (DDWG). The digital interface is used to connect a video source to a display device, such as a computer monitor. It was developed with the intention of creating an industry standard for the transfer of digital video content.



VGA:


Video Graphics Array (VGA) refers specifically to the display hardware first introduced with the IBM PS/2 line of computers in 1987,[1] but through its widespread adoption has also come to mean either an analog computer display standard, the 15-pin D-subminiature VGA connector or the 640x480 resolution itself. While this resolution was superseded in the personal computer market in the 1990s, mobile devices have only caught up in the last few years.



S-Video:
Separate Video, commonly known as S-Video, Super-Video and Y/C, is a signaling standard for standard definition video, typically 480i or 576i. By separating the black-and-white and coloring signals, it achieves better image quality than composite video, but has lower color resolution than component video.

Component video:

Component video is a video signal that has been split into two or more component channels. In popular use, it refers to a type of component analog video (CAV) information that is transmitted or stored as three separate signals. Component video can be contrasted with composite video (NTSC, PALor SECAM) in which all the video information is combined into a single line-level signal that is used in analog television. Like composite, component-video cables do not carry audio and are often paired with audio cables.



SMA Connector


SMA (SubMiniature version A) connectors are semi-precision coaxial RF connectors developed in the 1960s as a minimal connector interface for coaxial cable with a screw type coupling mechanism. The connector has a 50 Ω impedance. It is designed for use from DC to 18 GHz.

SMC Connector

SMC (SubMiniature version C) connectors are coaxial RF connectors developed in the 1960s.

 

TNC connector

 




The TNC (Threaded Neill–Concelman) connector is a threaded version of the BNC connector. The connector has a 50 Ω impedance and operates best in the 0–11 GHz frequency spectrum. It has better performance than the BNC connector at microwave frequencies.




 SMB Connector
 
SMB (SubMiniature version B) connectors are coaxial RF connectors developed in the 1960s. SMB connectors are smaller than SMA connectors.
They feature a snap-on coupling and are available in either 50 Ω or 75 Ω impedance. They offer excellent electrical performance from DC to 4 GHz.


MCX Connector


MCX (micro coaxial) connectors are coaxial RF connectors developed in the 1980s. They have the same inner contact and insulator dimensions as the SMB connector but are 30% smaller.

MMCX Connector

MMCX (micro-miniature coaxial) connectors are coaxial RF connectors similar to MCX but smaller.

Optical fiber connector
 
An optical fiber connector terminates the end of an optical fiber, and enables quicker connection and disconnection than splicing. The connectors mechanically couple and align the cores of fibers so light can pass.