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Communications technology

Qualification dates
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Electronic communication is ubiquitous in homes, offices and urban environments. You probably regularly use mobile devices, Wi-Fi and broadband. What makes such forms of communication possible? How do they relate to each other? Why is their performance so variable? This module gives you an insight into these and other questions by looking at the fundamental principles of communications technologies. Through these principles, you’ll gain an insight into the possibilities and constraints of modern communications technology.

What you will study

Block 1
Block 1 concerns the physical aspects of signals and their environment. You will study the theory and practice of signals (such as how electrical and radio signals can represent data), the propagation of signals through space and through materials, and the physical media that are used to convey signals, such as optical fibres, free space and conducting materials. Issues of noise and spectrum availability are ever-present because they set limits on what is possible. Accordingly you will study and use Shannon’s theorem, which specifies the maximum rate at which information can be sent over a channel of a specified bandwidth in the presence of noise. You will also study some concepts from Fourier’s theorem, which shows how an information-bearing signal occupies a band of frequencies rather than a single frequency.

Block 2
The second block concerns the nature and types of codes that are used to represent digital data. Although digital data is thought of as a succession of zeros and ones, the way those zeros and ones represent data needs ingenuity because perfect transmission in the presence of electrical noise (or interference) is impossible; and noise is unavoidable. In practice, the probability of error must be made sufficiently low, and this is achieved by use of error detecting and error correcting codes, which add extra zeros and ones to the data. You will study some of the main coding methods used to add resilience to signals. You will also look at some of the techniques used to reduce the amount of data imperceptibly so that files can be compressed.

Block 3
The final block looks at the principal types of access network in use. These are the networks used to connect users to the main data and telephony trunk routes. They include mobile data (3G, 4G and 5G), DSL broadband (which is the type delivered over a user’s fixed-line telephone connection), Wi-Fi, optical fibre and co-axial cable. The basic principles of these are covered with a view to uncovering their similarities (such as the increasing adoption of orthogonal frequency division techniques) and the factors that affect the performance of these types of network. The block concludes by looking at the implementation of security and virtual private networks in the context of teleworking.

If you are considering progressing to The computing and IT project (TM470), this is one of the OU level 3 modules on which you could base your project topic. Normally, you should have completed one of these OU level 3 modules (or be currently studying one) before registering for the project module.

Entry requirements

You must have passed one of the following modules:

You should understand the distinction between analogue and digital, and be familiar with:

  • the use of binary numbers to represent digital data
  • sines and cosines.

You should also understand and be able to perform basic manipulation of algebraic terms and to read graphs with linear and logarithmic scales.

To prepare for this module, we recommend Communication and information technologies (TM255) as suitable preparation.

If you have any doubt about the suitability of this module, speak to an adviser.

What's included

You’ll have access to a module website, which includes:

  • a week-by-week study planner
  • course-specific module materials
  • online activities and quizzes
  • audio and video content
  • assessment details and submission section
  • online tutorial access
  • access to student and tutor group forums.

You’ll also be provided with three printed module books, each covering one block of study.

You will need

A calculator with standard scientific functions.

Computing requirements

You’ll need broadband internet access and a desktop or laptop computer with an up-to-date version of Windows (10 or 11) or macOS Ventura or higher.

Any additional software will be provided or is generally freely available.

To join in spoken conversations in tutorials, we recommend a wired headset (headphones/earphones with a built-in microphone).

Our module websites comply with web standards, and any modern browser is suitable for most activities.

Our OU Study mobile app will operate on all current, supported versions of Android and iOS. It’s not available on Kindle.

It’s also possible to access some module materials on a mobile phone, tablet device or Chromebook. However, as you may be asked to install additional software or use certain applications, you’ll also require a desktop or laptop, as described above.

Teaching and assessment

Support from your tutor

Throughout your module studies, you’ll get help and support from your assigned module tutor. They’ll help you by:

  • Marking your assignments (TMAs) and providing detailed feedback for you to improve.
  • Guiding you to additional learning resources.
  • Providing individual guidance, whether that’s for general study skills or specific module content.
  • Facilitating online discussions between your fellow students, in the dedicated module and tutor group forums.

Module tutors also run online tutorials throughout the module. Where possible, recordings of online tutorials will be made available to students. While these tutorials won’t be compulsory for you to complete the module, you’re strongly encouraged to take part.


The assessment details for this module can be found in the facts box.

If you have a disability

The OU strives to make all aspects of study accessible to everyone and this Accessibility Statement outlines what studying TM355 involves. You should use this information to inform your study preparations and any discussions with us about how we can meet your needs.

Future availability

Communications technology (TM355) starts once a year – in October.

This page describes the module that will start in October 2024.

We expect it to start for the last time in October 2026.

Course work includes:

3 Tutor-marked assignments (TMAs)

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