Ariel Corp., 433 River Rd., Highland Park, NJ 08904
Res. Lab. of Electron., MIT, Cambridge, MA 02139
Jont B. Allen
AT&T Bell Labs., Murray Hill, NJ 07974
SYSid stands for SYStem IDentification. The software package runs on a DOS platform with the Ariel DSP-16+ installed. The basic concept of SYSid operation is simple. SYSid generates a stimulus (i.e., chirp, tones, user-defined, etc.) and synchronously averages the measured response. It is important to synchronously average a system response in order to obtain accurate phase information. SYSid then uses FFT techniques to deconvolve the stimulus from the measured response and to further analyze the data. From this basic mode of operation SYSid can perform many types of analyses including phase responses, group delay, impulse response, Hilbert envelope, reverse energy time curve, RT60, waterfall displays, electrical impedance, etc. In addition to these linear measurements, SYSid also provides the capabilities to make distortion measurements due to nonlinearities in the system. These include harmonic distortion, intermodulation distortion, THD+N, and input--output functions. With the current incarnation of SYSid each channel can be up to 32k sample points. Each channel is 16 bits and can be sampled at a maximum rate of 50 kHz. Examples of measurements made in areas of room acoustics, transducer design, and auditory physiology will be presented.