The Communication Medium

Before writing about the communication media, I would like to explain some terms or definitions related to data communications. When we talk about he data transmission, there are two types of transmissions. One is called serial transmission and second is called parallel transmission. As shown by the name, in serial transmission data transmitted on bit by bit. At a time only one bit will transmit whereas on the other hand when we talk about the parallel transmission data transmitted in sets of 8, 16 or 32 bits at a time. So, the parallel transmission is much faster as compare to the serial transmission but we use this parallel transmission only for short distances but when we want to transmit data long distance then the serial transmission is recommended.
Now, we come to our post title “the Communication Media” media is a source which, we use to transfer data from one place to another or in other words we can say that when we transfer data from one place to another place, we must use some sources to transfer data from one place to another place, we must use some sources to transfer it, these sources are called the “Communication Media”, Furthermore, these media has further two categories, Guided Media and the Unguided Media. When we use some physical media for our communication such as cables that is called guided media. On the other hand when our data transfers through some non-physical resource, this is called unguided media. The unguided media only used as a medium for data traveling, and not guide the signals towards any specific path that’s why this called unguided media. Microwave transmission and the satellite communication are its examples. When we talk about the microwave transmission, it is high-speed data transmission media but in this media we have to face little problem that signals travel only in straight lines so, we have to use microwaves antennas on a very high place to avoid the earth curvature. The 30 miles height for microwave antennas is recommended. These antennas receive signals from the previous antenna and then transmit it to the next antenna. Satellite communication is another form of unguided media. In these media two things involves. First, earth station and second satellite station. The earth station throws the signals to the satellite station, which is almost 23,000 miles to 24,000 miles above the earth that satellite station boosts up the signals and then transmit them to another earth station. So, these were the examples of unguided communication media. Now we will talk about the guided media
When the signals use some physical media for communication or when the signals travel through some physical media, this is called Guided Media. The following are the examples of Guided Media.
Coaxial Cable
Coaxial Cables are recommended within the range of one Kilometer or for the local area network. It is a copper wire that surrounded by the insolating material
Twisted Pair
These are the Cables of thin diameter, in the form of twisted pairs but it is not as reliable as the Coaxial Cable
Fiber Optic Cable
This is the fastest medium and it consists of hundred of thin glass. It also provides the high security level but it has also a disadvantage that it cannot support for the long distances.

Modes of Data Communication

When we talk about the data communications. It involves the communication of data between two devices, mostly between the computers and sometimes other devices like cell phones, radio and T.V etc. the data travels in some particular direction or in other words, I can explain that when any data communication activity performed, there involves sending devices and receiving devices and the data, which, is being communicated, travels from sender to receiver. So, the direction in which the data travels is called “Data Communication Mode”. This data communication mode has following types.
Simplex Mode
In simplex mode type, the data travels in only one direction and there is no possibility to change the direction of data. In other words, we can say that the direction of data will always be same between the two communicating devices. The device which is receiving the data (Receiver) cannot send the data in reply, were as on the other hand the sender will always send the data and cannot receive the data in reply. So, we can say that in simplex mode of data, the data always travels in only one direction and that direction is from sender to receiver.
Half-Duplex Mode
The second type of data communication mode is “Half-Duplex Mode”. In this type the direction of data could be towards the both sides. I mean to say that data travels from sender to receiver and the receiver, in response can also send the data to sender. We can understand this Half-Duplex Mode further by the example of a server and client communication. We have a database on server and on the other hand we have a client computer. Now from the client side we send a query to server where we ask for all the records employs having the grade three. So, when we write the query on the client computer and send it to the server, the direction of data is from client to server, in response of this query, server sends all the records (data according to query) to client computer. Now, the direction of data is from server to client. So, the data direction of data is in both directions, first from client to server, then from server to client. The further important point of Half-duplex Mode is it, that though, the data ravels in both directions but at a time data can travel in only one direction, when the activity is completed in one direction, then second activity will start in other direction. In short, we can say that data cannot travel in both directions simultaneously. Though, the direction of data could be change. Half-Duplex mode is better than the Simplex Mode, but it is not a quick communication mode because the device will have to wait to change the direction until the communication in one direction is completed.
Full-Duplex Mode
The third and the speediest type of data communication mode is the Full-Duplex Mode. In this type data can be travel in both directions at a time. The sender can be receiver as at a time and the two devices send and receive data simultaneously. So, the Full-Duplex mode is the faster mode as for as the data communication modes are concerned.

Analog and Digital Signals

There are two types of signals one is called analog signals and the second type of signals is called digital signals. Analog signals are the continuous form of the wave. Whereas, the digital signals have only two possible values, the maximum value of he signals/waves or the minimum value of the signals/wave. Furthermore, we can define or understand the two types of signals in this way that the analog signals the value of the signals is always on changing form and the value of the signals is called amplitude. If we talk about the amplitude, the waves travel in the horizontal axes. While traveling on the horizontal axes the maximum value is called the maximum amplitude same way the minimum value, while traveling on horizontal axes, is called the minimum amplitude. When the signals reach at its maximum amplitude next the decline of the signals starts and the value continuously decreases until it reaches to its minimum amplitude. After that again the value of signals start to increase and increases until again it reaches to its maximum amplitude. This process from the maximum amplitude to the minimum amplitude and then again to the maximum amplitude is called a ‘Cycle’. These cycles complete in so swiftly and the number of these cycles completed in one second is called the frequency.
Whereas on the other hand, if we talk about the second type of signals, that are called the digital signals, we can only find the maximum value or the minimum value and there is no value between these two values because in digital signals the change happens suddenly, not gradually and continuously as it happens in analog form.
Now, when we talk about the data communications of computer networking, we come to know that these types, analog and digital are closely concerned with each other. As we have already discussed in our previous post “Data communication and its elements” that all the communication within the computer happens in digital type or in other words, computer only understands the digital signals where as telephone lines required as source of communication in WAN (Wide Area Network) and the telephone lines only support analog signals, so, the conversion is required from digital to analog and from analog to digital. And for the conversion purposes, we need encoder and decoder. Modem is the example of encode and decoder devices. Modem takes the digital signals form computer, converts it into analog form and these analog signals travel through the telephone lines and on the other end, again modem takes the analog signals and convert them in digital form, so, that computer can understand these signals.
So, in the end we can summarize our post in the following words that there are two types of signals, one is called analog signals and second is called digital signals. In analog signals travel horizontally and the value of any place is called amplitude, the process of maximum amplitude to minimum and from minimum to maximum is called a cycle.
Computers only understand the digital signals and telephone lines only support analog signals. So, encoders and decoders used for conversion purposes.

Data Communication And Its Elements

When we transfer data/information from one place to another this process of transferring data/information is called “Data Communication”. Now there are different ways and mediums to perform the data communications, and it depends on the distance between the locations of devices/computers. The following elements involve performing a data communication. Lets know about these elements.
First of all, there is information or data, which, we want to transfer from one place to another. We have discussed in our very first post about the data and data types. Again for reminder, the data/information may be in four forms, text, image, audio, video or the combination of these types. So, the data or information that, we want to transfer is called message.
Now, the next step is the source which, we use to send that data. I means to say that I have selected the data/information to communicate but to transfer it we need some device. This device is called transmitter or sender. Computers are mostly used as transmitter/senders. So, we have selected the message and sender/transmitter now we need the source or medium which, the sender will use to send the data/information if there is little distance between the communicating devices (sender and receiver) we can connect these devices with the wire but if there is long distance between the sender and receiver. Then the source of data traveling may be telephone line, microwaves or a fiber optics. In short, the medium is required for data communication and this medium may be fiber optic, telephone line or the microwaves.
Now, before I write about the next element involves in data communication, there is need to explain little but about the analog and digital signals. As we know that all the computer’s internal communication is based on digital signals. Because computer knows only binary language 0 and 1, and this binary language is digital language. The computers only understand and communicate in binary (digital) language. But if our medium is such channel which, and not support digital signals and only work with analog signals, then we need encoder and decoder. The only function of encoder and decoder is to convert analog signals into digital signals and digital signals into analog signals. We explain this encoder and decoder with the example of modem. I think everybody who uses the Internet services from his/her computer is familiar with the device called modem. This modem is encoder and decoder device. When we connect to the Internet our data communication starts at once. This communication performed through the telephone line the modem’s function is to convert the incoming data (which is in analog form) into digital formant as well the outgoing data (which is in digital form) into analog form. So, we can say that the devices, which convert analog into digital and digital into analog, are called encoder and decoder devices.
So, the next element involves in data communication is receiver as we have sender to send the data/information, same way we have receiver to receive that data/information on the other end.
In short, if we take a look over the “Data communications and its elements”. We can summarize it in the way, that when we transfer some data/information, in its any form, the process of transferring is called “Data Communication” and the message (data/information) is the material we want to transfer or receive, sender is the device to send the message, Medium is the source to send the message. This medium could be fiber optics, telephone line or micro ways. Further, there involves decoder or encoder to convert the data/information into digital to analog as well analog to digital form and finally receiver receives the data/information.