Exploring communications technology
Exploring communications technology

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Free course

Exploring communications technology

1.2 Non-periodic signals

Communications is all about transferring information. A periodic signal, though, has limited possibilities for conveying information because of its predictability. After receiving a few cycles and establishing what the pattern is, we know the cycles that follow will be exactly the same. The signal may convey important information when it begins, as in the case of a fire alarm, where there is a call to immediate action as soon as the sound is heard. But a signal that never varies in amplitude, frequency, phase or any other aspect conveys little if any further information to a recipient. So in practical communications, exactly periodic signals are the exception. Signals that carry real information, such as speech, music or video, do not repeat endlessly.

Non-periodic signals (also known as aperiodic signals), unlike periodic signals, do not have just one particular frequency. Instead, they are spread out over a continuous range of frequencies. For example, a speech signal ranges from around 100 Hz to a few thousand Hz (for telephone-quality speech, a range of 300 Hz to 3400 Hz is often assumed).

TM355_1

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to University-level study, we offer two introductory routes to our qualifications. You could either choose to start with an Access module, or a module which allows you to count your previous learning towards an Open University qualification. Read our guide on Where to take your learning next for more information.

Not ready for formal University study? Then browse over 1000 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus371