Skip to main content

300x250 Ads

Transmission-Media

By Ashik
 Transmission-Media
Transmission Media or Communications media are the paths, or physical channels, is that, over which information travels from one place to another. A key aspect of communication is the movement of information electronically from one place to another. It may be as simple as sending information from one office to another in the same building, or it may be as far- reaching as sending information around the word. Whatever the case, information/signal must travel over some path from its source to its destination.

What are the types of Transmission media?

Signals are usually transmitted over some transmission media that are broadly classified in to two categories.

Guided Media/bounded: These are those that provide a conduit from one device to another that include twisted-pair, coaxial cable and fiber-optic cable. A signal traveling along any of these media is directed and is contained by the physical limits of the medium. Twisted-pair and coaxial cable use metallic that accept and transport signals in the form of electrical current. Optical fiber is a glass or plastic cable that accepts and transports signals in the form of light.

Unguided Media/unbounded: This is the wireless media that transport electromagnetic waves without using a physical conductor. Signals are broadcast either through air. This is done through radio communication, satellite communication and cellular telephony.


Classes of Transmission Media
  •     Conducted or guided media     
  •    use a conductor such as a wire or a fiber optic cable to move the signal from sender to receiver     
 
  •       Wireless or unguided media
 
  •   use radio waves of different frequencies and do not need a wire or cable conductor to transmit signals


 
Design Factors for Transmission Media

  1.  Bandwidth: All other factors remaining constant, the greater the band-width of a signal, the higher the data rate that can be achieved. 
  2. Transmission impairments: Limit the distance a signal can travel.
  3.  Interference: Competing signals in overlapping frequency bands can distort or wipe out a signal
  4.  Number of receivers: Each attachment introduces some attenuation and distortion,    limiting distance   and/or data rate.

Download
Labels:

Comments

Post a Comment

Popular posts from this blog

Armature Winding ,Pole Pitch, Coil Span, Commutator Pitch

By Ashik
Now we are going to discuss about armature winding in details. Before going through this section, we should understand some basic terms related to armature winding of dc generator . Pole Pitch Definition of Pole Pitch The pole pitch is defined as peripheral distance between center of two adjacent poles in dc machine. This distance is measured in term of armature slots or armature conductor come between two adjacent pole centers. This is naturally equal to the total number of armature slots divided by number of poles in the machine. If there are 96 slots on the armature periphery and 4 numbers of poles in the machine, the numbers of armature slots come between two adjacent poles centers would be 96/4 = 24. Hence, the pole pitch of that dc machine would be 24. As it is seen that, pole pitch is equal to total numbers of armature slots divided by total numbers of poles, this can alternatively referred as armature slots per pole . Coil Span or Coil Pitch Coil of
Post a Comment
Read more

Propagation-Radio-Waves

By Ashik
Radio Wave Propagation types
Post a Comment
Read more

Coding

By Ashik
Binary Coding 1. Binary Coded Decimal (BCD) Binary coded decimal (BCD) is a way to express each of the decimal digits with a binary code. There are only ten code groups in the BCD system, so it is very easy to convert between decimal and BCD. Because welike to read and write in decimal, the BCD code provides an excellent interface to binary systems. Examples of such interfaces are keypad inputs and digital readouts. The 8421 Code: The 8421 code is a type of BCD (binary coded decimal) code. Binary coded decimal means that each decimal digit, 0 through 9, is represented by a binary code of four bits. The designation 8421indicates the binary weights of the four bits 2 3 , 2 2 , 2 1 , 2 0 . The ease  of conversion between 8421 code numbers and the familiar decimal numbers is the main advantage of this code.  All wehave to remember are the ten binary combinations that represent the ten decimal digits as shown in Table 1. The 8421 code is the predominant BCD code, and when we ref
Post a Comment
Read more

Add