Collage of Engineering
Department of Electrical Engineering
Digital Signal Processors
Mohammed Mohammed Al-Sanabani | 503/2008 | Telecom | 4th Level
Abstract During the past decade digital signal processors (DSPs) have hit critical mass for high-volume applications. Today, the entire digital wireless industry operates with DSP-enabled handsets and base stations. This paper gives a plain introduction to DSP devices. The discussion focuses on the digital electronics aspects of DSP as well as applications of DSPs. DSP architecture, characteristics are explained in the discussion followed by a major application of DSPs in the field of Telecommunications.
Keywords: DSP, Signal Processing, Digital Electronics, Microprocessors, Embedded Systems
Digital signal processing is one of the core technologies, in rapidly growing application areas, such as wireless communications, audio and video processing and industrial control. The number and variety of products that include some form of digital signal processing has grown dramatically over the last few years. DSP has become a key component, in many of the consumer, communications, medical and industrial products which implement the signal processing using microprocessors, Field Programmable Gate Arrays (FPGAs), Custom ICs etc. Due to increasing popularity of the above mentioned applications, the variety of the DSP-capable processors has expanded greatly. DSPs are processors or microcomputers whose hardware, software, and instruction sets are optimized for high-speed numeric processing applications, an essential for processing digital data, representing analog signals in real time. The DSP processors have gained increased popularity because of the various advantages like reprogram ability in the field, cost-effectiveness, speed, energy efficiency etc. From Analog to Digital
Figure 1: A simple DSP system
There are many reasons why one would want to process an analog signal in a digital fashion by converting it into a digital signal (Figure 1). The main reason is that digital processing allows programmability. The same DSP hardware can be used for many different applications by simply changing the code residing in memory. Another reason is that digital circuits provide a more stable and tolerant output than analog circuits—for instance, when subjected to temperature changes. In addition, the advantage of operating in digital domain may be intrinsic. For example, a linear phase filter or a steep-cutoff notch filter can only be realized by using digital signal processing techniques, and many adaptive systems are achievable in a practical product only via digital manipulation of signals. In essence, digital representation (0s and 1s) allows voice, audio, image, and video data to be treated the same for error-tolerant digital transmission and storage purposes.
DSPs and other types of micro-processors have borrowed structures from each other, so that the line sometimes seems blurred where one type of processor leaves off and another begins. DSPs have become more supportive of the types of functions traditionally performed by microcontrollers and high-end RISC microprocessors. Interrupt support, which is critical to multitasking in embedded control systems, is now a regular feature of many DSPs that are meant to combine control and signal-processing functionality in a single device. Direct Memory access control and various types of input/output peripherals are also routinely integrated into DSPs to pro-vide the system-level support needed in a single- or satellite-processor application. Two-level cache memories have been adapted from high-end RISC engines for the special requirements of DSPs. The two-level cache architecture makes a relatively small on-chip memory look like a much larger one to the core—enabling extremely fast DSPs to operate without outstripping the data available at a given time. At the same time,...