IntroductionWhen electronic devices transfer information to another electronic device, the devices must know when the data flow begins and ends. This is done with signals for synchronization.iThis report will describe the two forms of data communication in terms of physical interfaces and modes of operation. It will describe the characteristics of data communications equipment as they relate to synchronous and asynchronous communication, including modems, network terminal units, and sending and receiving equipment. Define synchronous and asynchronousSynchronization: the receiver is able to determine when a signal begins to arrive and when it is finished. It must also know the duration of each signal.Asynchronous transmission: Asynchronous signaling methods use only 1 signal. The receiver uses changes on that signal to determine the speed and timing of the transmitter, then synchronizes a clock on the correct timing with the transmission speed. A pulse from the local clock indicates when another bit is ready. Asynchronous transmission is slower but less expensive and effective for low-speed data communication. Synchronous Transmission: Synchronous signaling methods use 2 different signals. A pulse on one signal indicates when another bit of information is ready on the other signal. This is high-speed data communication. COMPARISON BETWEEN ASYNCHRONOUS AND SYNCHRONOUS TRANSMISSION asynchronous synchronous Suitable for low speed serial transmission. It can reach higher speeds than asynchronous one. Does not include error checking function. Error checking functionality. One (or more) characters are contained in an envelope start and stop bits. Groups characters into blocks. Less efficient than synchrono......middle of paper......r line, United States NEC Corporation (Tokyo, JP) 4999836 http://www.freepatentsonline.com/4999836.htmlUK Yahoo.com (2009) An NTU is a modem....why is it connected to the Cisco router? what is its function? http://uk.answers.yahoo.com/question/index?qid=20091118020312AAjeaKkContent-Wire (2001) Deutsche Telekom implements ATM network access solution http://www.content-wire.com/deutsche-telekom- deploys-atm -network-access-solutionVoxTechnologies Corp (2010) 2902 Network Termination Unit MainStreet http://www.voxtechnologies.com/2902_mainstreet_network_termination_unit.htmRAD Data Communications, Ltd. (2010) Network Termination Unit multiservice ACE-201 http://uk.precisionnews.com/article_ACE-201-multiservice-network_5505. htmlErrealMedia (2010) OSI Reference Model for Networking Standards; History of the OSI model; OSI layers in action http://www.erealmedia.com/cms125/