An Introduction to Digital Signal Processors

What is a DSP?
Digital Signal Processors (DSPs) take real-world signals like voice, audio, video, temperature, pressure, or position that have been digitized and then mathematically manipulate them. A DSP is designed for performing mathematical functions like "add", "subtract", "multiply" and "divide" very quickly.

Signals need to be processed so that the information that they contain can be displayed, analyzed, or converted to another type of signal that may be of use. In the real-world, analog products detect signals such as sound, light, temperature or pressure and manipulate them. Converters such as an Analog-to-Digital converter then take the real-world signal and turn it into the digital format of 1's and 0's. From here, the DSP takes over by capturing the digitized information and processing it. It then feeds the digitized information back for use in the real world. It does this in one of two ways, either digitally or in an analog format by going through a Digital-to-Analog converter. All of this occurs at very high speeds.

To illustrate this concept, the diagram below shows how a DSP is used in an MP3 audio player. During the recording phase, analog audio is input through a receiver or other source. This analog signal is then converted to a digital signal by an analog-to-digital converter and passed to the DSP. The DSP performs the MP3 encoding and saves the file to memory. During the playback phase, the file is taken from memory, decoded by the DSP and then converted back to an analog signal through the digital-to-analog converter so it can be output through the speaker system. In a more complex example, the DSP would perform other functions such as volume control, equalization and user interface.

A DSP's information can be used by a computer to control such things as security, telephone, home theater systems, and video compression. Signals may be compressed so that they can be transmitted quickly and more efficiently from one place to another (e.g. teleconferencing can transmit speech and video via telephone lines). Signals may also be enhanced or manipulated to improve their quality or provide information that is not sensed by humans (e.g. echo cancellation for cell phones or computer-enhanced medical images). Although real-world signals can be processed in their analog form, processing signals digitally provides the advantages of high speed and accuracy.

Because it's programmable, a DSP can be used in a wide variety of applications. You can create your own software or use software provided by ADI and its third parties to design a DSP solution for an application.

For more detailed information about the advantages of using DSPs to process real-world signals, please read Part 1 of the article from Analog Dialogue titled: Why Use DSP? Digital Signal Processing 101- An Introductory Course in DSP System Design.

What's Inside a DSP?
A DSP contains these key components:

• Program Memory: Stores the programs the DSP will use to process data
• Data Memory: Stores the information to be processed
• Compute Engine: Performs the math processing, accessing the program from the Program Memory and the data from the Data Memory
• Input/Output: Serves a range of functions to connect to the outside world

Recommended Reading
Digital Signal Processing is a complex subject that can overwhelm even the most experienced DSP professionals. Although we have provided a general overview, Analog Devices offers the following resources that contain more extensive information about Digital Signal Processing:

• The Scientist and Engineer's Guide to Digital Signal Processing
• Analog Dialogue Series: Digital Signal Processing 101- An Introductory Course in DSP System Design
  • Part 1: Why use DSP? DSP Architecture and DSP Advantages Over Traditional Analog Circuitry
  • Part 2: Learn More About Digital Filters
  • Part 3: Implement Algorithms on a Hardware Platform
  • Part 4: Programming Considerations for Real-Time I/O
• Let's Talk DSP: Commonly Use Worlds and What They Mean

DSP workshops are a very fast and efficient way to learn how to use Analog Devices DSP chips. The workshops are designed to develop a strong working knowledge of Analog Devices' DSPs through lecture and hands-on exercises. For schedule and registration information, visit the DSP Workshops page.

Next we will discuss the process of designing with ADI DSPs, from selecting the right DSP to integrating your design.

Proceed to the Quick Guide to Developing with ADI DSPs.   

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