Design and Implementation of a linear-phase equalizer in digital audio signal processing

This contribution presents the four phases of a project aiming at the realization in VLSI of a digital audio equalizer with a linear phase characteristic. The first step includes the identification of the system requirements, based on experience and (psycho-acoustical) literature. Secondly, the signal processing algorithms constituting the global design of the equalizer are computer simulated. The third step includes the realization of the equalizer design using one or more programmable DSP¿s. In order to minimize the number of DSP chips necessary for the realization, this step requires the optimization of the structure and mapping of the algorithm on the resources of the DSP. The number of processor cycles is crucial in this optimization. The purpose of the resulting prototype is to test and to validate in a digital audio environment the specification generated in the first step. The programmability of the DSP¿s allows for specification changes at this stage of the project. The fourth step is the VLSI implementatin of the validated algorithm of\ud the previous phase. For this purpose the structure of the algorithm is optimized in order to take full advantage of the silicon resources. Speed and required area are the crucial parameters in this optimization. The final step includes the testing of the completed chips together with a parallel designed and realized PCB in a digital audio environment. The presentation will emphasize the algorithmic and design considerations together with the results

<title>Improving display quality by a digital convergence correction system for multibeam CRTs</title>

In the field of medical imaging there is a need for high-resolution high-brilliance monochromatic CRT displays. However, at higher brightness levels the resolution of these displays decreases, due to the increasing spot size. In order to improve the performance of the CRT display a relatively simple method, called the multi-beam concept, is introduced. Using this technique a higher brightness can be realized without an increase of the spot size and therefore a better display quality can be achieved. However, for successful exploitation of the multi-beam concept it is necessary to minimize the convergence error of the CRT display. For this purpose two circuits have been realized, where the convergence error is reduced by an analogue and a digital method respectively. The analogue implementation means an improvement for the applicability of the multi-beam concept, however, in order to achieve major image quality improvement the use of the digital system is necessary