varri@cs.tut.fi (V{rri Alpo) (05/23/91)
Harmonic distortion is nonlinear distortion characterized by the appearance in the output of harmonics other than the fundamental component when the input wave is sinusoidal. What is the name of the distortion which does not appear at the harmonic frequencies of the fundamental component but at some other frequencies? This type of distortion is often introduced by nonlinear filters. Alpo Varri
sjreeves@eng.auburn.edu (Stan Reeves) (05/24/91)
In article <1991May23.070428.23505@funet.fi> varri@cs.tut.fi (V{rri Alpo) writes: >Harmonic distortion is nonlinear distortion characterized by the >appearance in the output of harmonics other than the fundamental >component when the input wave is sinusoidal. > >What is the name of the distortion which does not appear at the >harmonic frequencies of the fundamental component but at some >other frequencies? Discordant distortion? ;-) -- Stan Reeves Auburn University, Department of Electrical Engineering, Auburn, AL 36849 INTERNET: sjreeves@eng.auburn.edu
cdl@chiton.ucsd.edu (Carl Lowenstein) (05/24/91)
In article <1991May23.070428.23505@funet.fi> varri@cs.tut.fi (V{rri Alpo) writes: | Harmonic distortion is nonlinear distortion characterized by the | appearance in the output of harmonics other than the fundamental | component when the input wave is sinusoidal. | | What is the name of the distortion which does not appear at the | harmonic frequencies of the fundamental component but at some | other frequencies? Intermodulation -- carl lowenstein marine physical lab u.c. san diego {decvax|ucbvax} !ucsd!mpl!cdl cdl@mpl.ucsd.edu clowenstein@ucsd.edu
sdw@hpsad.HP.COM (Steve Warwick) (05/24/91)
>What is the name of the distortion which does not appear at the >harmonic frequencies of the fundamental component but at some >other frequencies? This type of distortion is often introduced >by nonlinear filters. ---------- In a memoryless, non-time-varying analog system, driven by a sinusoid, you cannot get distortion at frequencies at other than the harmonics of the fundamental. this is a direct result of the fact that any memoryless nonlinear system can be represented by a taylor series expansion. If the system has memory, you still cannot get signals at frequencies other than harmonics. This comes from examining volterra series expansions of such systems. If the system is time varying, or is a sampled system, one can get either "mixing products" or "aliasing", so I guess the answer to your question is one of those terms. since this is a DSP group, I guess the correct term is "aliasing".
lou@caber.valid.com (Louis K. Scheffer) (05/27/91)
varri@cs.tut.fi (V{rri Alpo) writes: >Harmonic distortion is nonlinear distortion characterized by the >appearance in the output of harmonics other than the fundamental >component when the input wave is sinusoidal. >What is the name of the distortion which does not appear at the >harmonic frequencies of the fundamental component but at some >other frequencies? This type of distortion is often introduced >by nonlinear filters. In RF work these are called "spurs", which is short for spurious responses (or outputs). You often find them at f+60Hz, f-60Hz, f+-(twice the IF frequency), etc. Sometimes they are considered part of the "noise", even though they are correlated with the input. In audio work you get "intermodulation distortion", where some non-linearity produces sum and difference frequencies from two pure tone inputs. In digital work you get "aliasing". For example, a 3 KHz square wave into a 44.1 KHz sampled system (say CDs) might produce an 0.9 KHz output if the input filter was not good enough. (From the 15th harmonic of the input aliased by the 44.1 KHz sampling rate.) I'm sure there are additional technical names, but most people who work with them call them things that shouldn't be repeated around small children. -Lou Scheffer
grayt@Software.Mitel.COM (Tom Gray) (05/28/91)
In article <1088@chiton.ucsd.edu> cdl@chiton (Carl Lowenstein) writes: |In article <1991May23.070428.23505@funet.fi> varri@cs.tut.fi (V{rri Alpo) writes: || Harmonic distortion is nonlinear distortion characterized by the || appearance in the output of harmonics other than the fundamental || component when the input wave is sinusoidal. || || What is the name of the distortion which does not appear at the || harmonic frequencies of the fundamental component but at some || other frequencies? | | Intermodulation | In the communication business, nonlinear distortion is is lumped together under the term "Quantizing Noise". I know this is a misnomer but it is the term used for this type of distortion.
gingell@aurs01.UUCP (Mike Gingell) (05/29/91)
In article <1991May23.070428.23505@funet.fi> varri@cs.tut.fi writes: >What is the name of the distortion which does not appear at the >harmonic frequencies of the fundamental component but at some >other frequencies? This type of distortion is often introduced >by nonlinear filters. I would call it parametric distortion or intermodulation i.e a distortion due to the modulation of some transfer parameter of the network by the signal being transferred. Mike Gingell, Alcatel, Raleigh, NC USA (919) 850-6444 UUCP: ...!mcnc!aurgate!aurfs1!gingell Internet: gingell%aurfs1%aurgate@mcnc.org
john@qip.UUCP (John Moore) (06/02/91)
In article <59881@aurs01.UUCP> gingell@aurw90.UUCP (Mike Gingell) writes: >In article <1991May23.070428.23505@funet.fi> varri@cs.tut.fi writes: ]>What is the name of the distortion which does not appear at the ]>harmonic frequencies of the fundamental component but at some ]>other frequencies? This type of distortion is often introduced ]>by nonlinear filters. ] ]I would call it parametric distortion or intermodulation i.e a ]distortion due to the modulation of some transfer parameter of ]the network by the signal being transferred. In RF Engineering, intermodulation means the mixing of different frequency components of a signal. This mixing occurs through ANY nonlinearity in the system, and produces signals with frequency components as follows: Fd = nF1 +/- mF2 where n = 1.... and m = 1... This can be derived by observing that the transfer function with a nonlinearity can be represented by a power series: H = a + bf(x) + cf^2(x) ... If one substitutes the fourier representation of the signal into this, one ends up with terms where the signals are multiplied by powers of each other. This yields the classic sum and difference mixing formulae. Note that a system with nonlinearities, if presented with a pure sinusoid (single frequency signal), with produce only harmonic distortion. It takes more than one frequency in the input in order to observe intermodulation distortion. -- John Moore HAM:NJ7E/CAP:T-Bird 381 {ames!ncar!noao!asuvax,mcdphx}!anasaz!john USnail: 7525 Clearwater Pkwy, Scottsdale,AZ 85253 anasaz!john@asuvax.eas.asu.edu Voice: (602) 951-9326 Wishful Thinking: Long palladium, Short Petroleum Opinion: Support ALL of the bill of rights, INCLUDING the 2nd amendment! Disclaimer: The opinions expressed here are all my fault, and no one elses.