9309.doc - Topic 4.5.5 Asynchronous Transmission Learning...

Info icon This preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Topic 4.5.5 – Asynchronous Transmission Learning Objectives: At the end of this topic you will be able to; describe asynchronous character framing in terms of the start and stop bits, data bits and parity bit; appreciate that the ability to detect and correct errors that occur during digital transmissions is not possible with analogue systems; describe how using extra parity bits can provide error detection and correction; describe and use two-bit parity-bit systems to speed up data transfer by only having to retransmit half of the data when an error is detected describe and use a five parity-bit system to identify and correct a single error if it has occurred; realise that even with multiple parity-bit systems it is not always possible to detect and correct errors when more than one bit is affected; appreciate that there is a trade off between the ability to check and correct data and the extra transmission costs; realise that in very noisy or sensitive applications it is often essential to have a high level of data checking despite the extra cost involved. 1
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Module ET4 – Communication Systems Computer Communications. For humans to communicate with each other so that all of the message is understood they must use the same language. For electronic systems to communicate effectively with one another is should be obvious that they must also use the same language and systems to communicate with each other. There are currently two main methods used for data communication as shown below: a. Serial – i.e. one bit at a time. b. Parallel – i.e. the whole 8 bits at the same time. Within each of these two categories we could send the data using one of two systems i. Synchronously ii. Asynchronously In the time available for this course it would be impossible to look at all of these various systems in detail, as this is a major subject in its own right. For this course we will concentrate on Asynchronous Serial Communication . The purpose of this topic is to give a flavour of the issues that exist in the transfer of data from one system to another. Students are empowered to carryout further research into other methods if they are so inclined, however these will not be examined. Synchronous and Asynchronous Serial Communications. In this module we will concentrate on Asynchronous Serial Transmission but we will take a very brief look at synchronous communication first. For electronic systems to communicate they must exchange data at the same rate using the same voltage levels. Unless the two systems remain synchronised, data can become corrupted and may have serious consequences. Synchronous Serial Communication. Two synchronous serial communications systems are dealt with in this module. One system involves PCM / TDM which uses a channel(s) to 2
Image of page 2
Topic 4.5.5 – Asynchronous Transmission maintain synchronisation which is dealt with in another part of this unit (Topic 4.5.4).
Image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern