(c) 1994 ADS Technologies Inc.


Table of Contents

Overview | Operation | Controls | Specifications | References


Logic Induced Modulation (LIM) is a phenomenon that seriously degrades the performance of digital audio circuits. It is well explained in a paper presented to the AES and referred to at the back of this manual. The LIM Detector is unique as a jitter analysis tool. It works intuitively with you to help resolve the spectral components of jitter. The output of the LIM Detector is a 20KHz band limited audio signal. This signal can drive a Spectrum Analyzer to display the audio-band jitter spectrum.


The input of the LIM Detector is compatible with ordinary X10 high-impedance oscilloscope probes. A 1:1 probe may be necessary when examining a signal with low duty cycle, or slow rise time. The LIM Detector has sufficient tuning and capture-range to lock and track the multiples of common audio sampling rates from 32KHz to 48 KHz (+/- 600 ppm). Specifically, these are multiples of 2Fs to 768Fs, or frequencies from 64KHz to 36.8MHz. The best use of the LIM Detector is when its output is observed with an audio spectrum analyzer (analog or digitizing). The spectral components of the jitter are linked to specific causes and thereby reveal the relative contributions of errors from various sources in a system.



High frequency selected at Fs relative to 32, 44.1 and 48 Khz. Sixteen steps allow 2 Fs to 768 Fs supporting the most common digital audio sample rates. (Other frequencies are available on request.)


For more information please contact John Wright at (403) 968-1400 or email