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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 will gain an insight into the possibilities and constraints of modern communications technology. This module complements other modules relating to networking, human-computer interaction, and pervasive computing.

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 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 and 4G), 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

This is an OU level 3 module. OU level 3 modules build on study skills and subject knowledge acquired from previous studies at levels 1 and 2. They are only intended for students with recent experience of higher education in a related subject.

Normally, to study this module you should have studied least one of the OU level 1 modules, Discovering mathematics (MU123) or Essential mathematics 1 (MST124) (or their predecessors). You should be able to understand the distinction between analogue and digital, and be familiar with:

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

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

Prior study of Communication and information technologies (TM255), or its predecessor T215, is recommended as preparation for this OU level 3 module.

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

What's included

Most of the teaching material is in three printed books, one book for each block of the module. In addition, the module website will have supplementary items such as a study calendar, interactive online teaching material, assignments, additional reading.

You will need

A calculator with standard scientific functions.

Computing requirements

A computing device with a browser and broadband internet access is required for this module. Any modern browser will be suitable for most computer activities. Functionality may be limited on mobile devices.

Any additional software will be provided, or is generally freely available. However, some activities may have more specific requirements. For this reason, you will need to be able to install and run additional software on a device that meets the requirements below.

A desktop or laptop computer with either:

  • Windows 7 or higher
  • Mac OS X 10.7 or higher

The screen of the device must have a resolution of at least 1024 pixels horizontally and 768 pixels vertically.

To join in the spoken conversation in our online rooms we recommend a headset (headphones or earphones with an integrated microphone).

Our Skills for OU study website has further information including computing skills for study, computer security, acquiring a computer and Microsoft software offers for students.

Teaching and assessment

Support from your tutor

You will have a tutor who will help you with the study material, who will mark and comment on your written work, and whom you can ask for advice and guidance. We may also be able to offer group tutorials that you are encouraged, but not obliged, to attend. Where your tutorials are held will depend on the distribution of students taking the module. There will also be online tutorials and other collaborative activities (such as student forums), which will take place in the online forum for your tutor group. Throughout the module you can use this forum to keep in touch with your tutor and fellow students.

Contact us if you want to know more about study with The Open University before you register.


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

You must use the online eTMA system to submit your tutor-marked assignments (TMAs).

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 2019. We expect it to start for the last time in October 2022.

Course work includes:

3 Tutor-marked assignments (TMAs)
No residential school

Course satisfaction survey

See the satisfaction survey results for this course.