Two-Tone Test Method for Determining Frequency-Domain Transfer Functions
Abstract
A method has been developed and used to nonintrusively interrogate electronic systems to determine their characteristic response to electromagnetic energy. The method involves subjecting the system under test to two continuous wave signal sources of different frequencies, f sub h and f sub l, and measuring the difference frequency, Delta(f) (that is, f sub h - f sub l), emitted from the system under test. The difference frequency created by the mixing action of nonlinear electronic components within the system is a relative indication of the system's response to f sub h,f sub l. If the two source signals f sub h and flare incremented by the same frequency step size, Delta(f) remains constant in frequency and can be measured for each f sub h,f sub l value. The compilation of amplitude measures of Delta(f), normalized by the corresponding amplitude measures of f sub h,f sub l, provides a relative measure of the frequency-domain transfer function of the system under test. Although the present method provides only relative data, the economic benefits of using this method make it a viable alternative to high-tech, high-cost approaches. The method provides more than coupling data, since the measurement of Delta (f) is indicative of not only the relative coupling efficiency of the signal source (f sub h,f sub l) into the system, but also the relative response of the nonlinear circuit component(s) that mix the source signals. The present method is performed with the test equipment totally isolated from the system under test. Without the need for probes at circuit nodes, less time and effort are expended and the integrity of the system is not violated by instrumentation. Transfer functions, Frequency response, Beat frequency, Nonlinear transfer functions.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1994
- Accession Number
- ADA283452
Entities
People
- Vincent J. Ellis
Organizations
- United States Army Research Laboratory