Intermodulation distortion audio books

Audio engineers reference book, 2nd edition, focal press. Intermodulation is also referred to as intermodulation distortion, im, imd, intermod and intermod distortion. Using two signal generators of lowintensity ultrasonic tones, we demonstrate synthesis of audible byproducts below 20khz. Intermodulation distortion arises when a nonlinearity causes two or more signals to interact. Total harmonic distortion thd is calculated for signal with single frequency. This unique new book is your single resource for all issues related to intermodulation and multitone distortion in microwave and wireless circuits. Intermodulation distortion in microwave and wireless. Intermodulation distortion in passive devices was not necessarily a problem because the distortion levels were significantly below the noise floor of the broadcast system. The amplifier system contains a modulator and an output lowpass filter. Intermodulation im or intermodulation distortion imd is the amplitude modulation of signals. The nonlinear distortion of directional loudspeaker ieee xplore. Like harmonic distortion, it will be present in all speakers, but at what point does it become audible in bass frequencies. In this paper, an analysis of intermodulation distortion of class d audio amplifier is presented.

Intermodulation distortion audio glossary federal agencies. Evaluating harmonic and intermodulation distortion of mixed signals. Localized audible sounds synthesized from ultrasonic. Intermodulation distortion of class d audio amplifier.

Practically all audio equipment has some nonlinearity, so it will exhibit some amount of imd, which however may be low. Intermodulation with wireless microphones dbb audio. Intermodulation with wireless microphones 3 key points. Intermodulation news newspapers books scholar jstor december 2014 learn. An axiom experimental study by alan lofft, ian colquhoun and tom cumberland in the process of finding the amplifiers, loudspeakers, and subwoofers to bring the pleasures of high fidelity music into our homes, we encounter lists of technical specifications that include distortion measurements. Intermodulation is a phenomenon of combining undesired frequency components within an active system or from an external source. Journal of the audio engineering society volume 31, march 1983. John price, terry goble, in telecommunications engineers reference book, 1993. Intermodulation distortion in microwave and wireless circuits. A directional audible sound could be generated from the nonlinear interaction of. A two tone input signal produces harmonic distortion and intermodulation. Phase intermodulation distortion instrumentation and measurements. Intermodulation distortion in microwave and wireless circuits artech house. Is highfrequency intermodulation distortion a significant factor in.

Note, there are likely two cascading instances of intermodulation. Beginning with an overview of the general concepts of distortion in microwave and wireless. Introduction intermodulation distortion imd is a common problem in a variety of areas of electronics. Combination of two or more signals will create another signal which may fall into another frequency band of the system and cause interference to the system. Imd values are usually tested for audio products, but are rarely. Class d audio amplifier uses mosfets in switching mode is designed. Imd results when two or more signals of different frequencies are mixed together and additional signals are. Intermodulation im is a source of interference from the interaction between two or more signals at different frequencies when they are combined in a nonlinear system. The primary mechanism producing im in most devices continue reading. Intermodulation products and their frequency values relative to the fundamentals like harmonic distortion, intermodulation distortion is measured as a percentage, but as with the thd percentage, the percentage of intermodulation distortion may not be very meaningful with respect to audibility. Intermodulation distortion in microwave and wireless circuits jose carlos pedro, nuno borges carvalho. How does intermodulation distortion occur, what are the. Intermodulation distortion or imd has always existed in rf transmission paths. Imd is created when two or more audio tones beat with one another intermodulate in a nonlinear device to produce undesired new tones.