Propeller Head Plaza

Re: test for transients

66.179.49.35

[ Follow Ups ] [ Post Followup ] [ Thread: Display Email ] [ Propeller Head Plaza ] [ FAQ ]

mfc

(A)

In Reply to: Re: test for transients posted by 13th Duke of Wymbourne on July 15, 2003 at 11:40:24:

Hi,
>The intermods from the square wave harmonics will all fall on top of
>the harmonics themselves
The intermods could be seen when viewing the results from the sine
wave sim tests. These would start showing up (depending on level of
input signal) at around -130 dB. They were always off frequency from
the primary harmonics of the sine wave so I didn't worry about them.
>...and plot the output harmonic amplitudes in input intercept fashion
These types of graphs always made sense as a measure of linearity. I
remember seeing them applied to mixers in radio receivers. Always
wondered why they never showed up in audio. Do you have an example?
It would save a lot of time to work from an example.
>I'll look out a reference for you.
Those results sound really interesting. A reference would be *very*
useful. Thanks

Follow Ups:

Re: test for transients - Steve Eddy 13:13:08 07/15/03 (1)
Are you just interested in simply getting a picture of the total distortion? If so, your method should work fine.
Are you able to use an MLS stimulus in your simulation program? If so, with sufficient averaging, you should be able to separate the IM distortion from other distortion.
se

"Of course that's just my opinion. I could be wrong."
- Re: test for transients - mfc 13:27:49 07/15/03 (0)
  Hi Steve,
  > Are you just interested in simply getting a picture of the total > distortion?
  Yes, but broken down by harmonic. As long as the IM is low, then I
  think the test will be valid. I can see another test formulating
  which would look at the behavior of intermods.
  > Are you able to use an MLS stimulus in your simulation program?
  No, but that would be a real cool thing to do.
  > If so, with sufficient averaging, you should be able to separate the
  > IM distortion from other distortion.
  That is what I have is an FFT averaged over 1 to 1000's of a
  waveform period. The IM looks like a harmonic, only it is a
  non-multiple and generally low in level (as long as signal level
  is low).

This post is made possible by the generous support of people like you and our sponsors:

Kimber Kable

You can not post to an archived thread.