DSP Development Corporation

This article appeared in Microwaves & RF Magazine in December 1995.

DSP SOFTWARE UNRAVELS MISSILE TRACKING SIGNALS

This flexible tool simplifies comprehensive signal analysis of an almost unlimited number of parallel channels.

DIGITAL SIGNAL PROCESSING (DSP) SEEMS to replace more and more RF and analog functions with time. Given the ability to explore DSP capabilities in software, designers of commercial and military systems can create more-efficient architectures with full signal-analysis capabilities. Version 4.0 of the DADiSP program from DSP Development Corp. (Cambridge, MA) is one such software tool, with powerful DSP simulation routines that run on standard personal computers.

Due to its power in the simulation of military systems, the DADiSP program is the preferred signal analysis tool of Loral Vought Systems for diagnosing the electrical performance of the Patriot Advanced Capability (PAC-3) missile program. The software has also been adapted by NASA for use as a multi-channel spectrum analyzer in order to sort through deep-space signals for anomalies that might represent signs of extraterrestrial life.

While several commercial DSP programs are currently available, the DADiSP program may be the most powerful and yet easiest-to-use tool of the group. This latest Windows-based version of the program provides simple mouse-driven "point-and-click" access to all functions. A UNIX workstation version based on the Motif graphical user interface (GUI) is also available.

This latest version of DADiSP introduces the Series Processing Language (SPL) programming language. Modeled on C, SPL provides all programming facilities, including user-defined functions, looping functions, iterations, flexibility in choosing variables, conditional statements, and array references. A new function called "hot variable" provides insight into functions with changing variables. In using the hot variable feature, when a dependent element of a given formula changes, this function automatically re-evaluates the formula. Variables can contain complex or real numbers, integers, strings of numbers, series, and matrices.

The software is available with eight optional software modules, which can be accessed through pulldown menus or direct commands. These modules include advanced DSP, digital filter analysis, and neural networks. The advanced DSP module includes a wide range of algorithms, such as digital interpolation, advanced Fast Fourier transform (FFT) analysis, and power-spectral-density estimation capability.

The optional digital filter module provides full finite-impulse-response (FIR) and infinite-impulse-response (IIR) filtering capabilities. The software includes 15 FIR functions, nine IIR functions, and 12 miscellaneous digital filter functions.

The neural network module allows operators to create and train propagation networks typically used for pattern-recognition, image-processing, speech-recognition, and computer-vision functions. This module contains more than 15 menu-driven network design functions, including automatic data normalization and choice of hidden layers. The software supports unlimited input and output variables as well as an unlimited number of processing runs. Users can select statistical output processing information, such as desired mean square error, minimum gradient norm, and desired absolute error functions.

The DADiSP program runs on any IBM personal computer or compatible machine with the DOS 5.0 operator system or higher version, at least 640-KB conventional random-access memory (RAM), at least 8-MB extended memory, 10-MB available hard-disk memory, and a math coprocessor. The software is shipped with excellent documentation, although new users are advised to try the demonstration program supplied with the software. P&A: $1895; stock. DSP Development Corp., One Kendall Square, Cambridge, MA 02139; (617) 577-1133, FAX: (617) 577-8211.

ALAN CONRAD Special Projects Editor

Microwaves & RF Magazine

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