Monday 16 June 2014

What is the Difference Between Electronic and Electric?



In a number of instances, people tend to use the terms electronic and electricinterchangeably. While both terms are commonly employed when discussing electronics, there is a subtle difference between the correct usage of each word. Here is what you should know about the proper way to make use of both electronic and electric when speaking or writing.


Electric has to do with the general concept of electricity. It is generally acceptable to use the terms electric and electrical interchangeably. Essentially, the word "electric" will function as a way of qualifying the flow of electricity as it relates to a specific event. For example, if a fire starts due to a problem with wiring in a building, the event can be described as an electric or electrical fire, caused by the electric or electrical wiring. The use of electric identifies a source of power that serves to create a logical effect when conducted through a process or device.

Sunday 8 June 2014

Time Measurement Unit

Units for measuring time


half-hour
 NOUN
a period of 30 minutes
hour
 NOUN
a period of time that consists of 60 minutes. 30 minutes is usually called half an hour, 15 minutes can be called a quarter of an hour,and 45 minutes can be called three-quarters of an hour
hr
 ABBREVIATION
hour
m
 ABBREVIATION
minute

Thursday 5 June 2014

Shannon Channel Capacity

In 1944 Claude Shannon introduce a formula to determine the theoretical highest data rate for a a channel
C=B log 2(1+S/n)
In this formula, B is the bandwidth of the channel. S/N is the signal to noice ratio and C is the capacity (Shannon Capacity) in BPS.
We can calculate the theoretical highest bit rate of regular telephone.
A Telephone line normally has a bandwidth of 3000Hz. The signal to noise ratio is usually 3162-(35db) for this channel capacity is

       C=B log 2 (1+S/N)
       C=3000 log2 ((1+3162)
       C=3000 log2 (3163)
       C=3000*1162

       C=34860 BPS

Wednesday 28 May 2014

TCP/IP or OSI - Which one came first



The TCP/IP model, which is realistically the Internet Model, came into existence about 10 years before the OSI model.

History of TCP

       From 1973 to 1974, Cerf's networking research group at Stanford worked out details of the idea, resulting in the first TCP specification. A significant technical influence was the early networking work at Xerox PARC, which produced the PARC Universal Packet protocol suite, much of which existed around that time.

        In March 1982, the US Department of Defense declared TCP/IP as the standard for all military computer networking. In 1985, the Internet Advisory Board (later renamed the Internet Architecture Board) held a three-day workshop on TCP/IP for the computer industry, attended by 250 vendor representatives, promoting the protocol and leading to its increasing commercial use.

        In 1985, the first Interop conference focused on network interoperability by broader adoption of TCP/IP. The conference was founded by Dan Lynch, an early Internet activist. From the beginning, large corporations, such as IBM and DEC, attended the meeting. Interoperability conferences have been held every year since then. Every year from 1985 through 1993, the number of attendees tripled