Is there any test cd to test jitter using a scope ?

gaetan8888 · 9th August 2007, 10:10 AM

Hello

Is there any test cd to test jitter on a cd player by using a scope ?

Thank

Gaetan

oshifis · 9th August 2007, 01:34 PM

Test the DAC latch enable signal with a scope. The jitter you get there is the jitter of the system.

martin clark · 9th August 2007, 07:15 PM

Take a read through the works of the late Julian Dunn over at www.nanophon.com

An oscilloscope is no way to observe or measure jitter - because the 'scope's internal timbase is far worse. This means that you don't observe jitter directly on a scope, but an intermodulation product between the two timebases...

gaetan8888 · 10th August 2007, 07:57 AM

Hello

Yes, I seen that a scope don't do the job.

But I did found a 16bit/44.1kHz JTEST signal wave file. Made of a 11025Hz square wave with 229.6875Hz LSB.

So I did burn a cd with that signal and use it with my Denon DCM-420 cd player, and I use my sound card and a FFT software who go down to -140 db, the result seem good since my Denon have a jitter at -90db from the 11025Hz signal 0 db.

Gaetan

oshifis · 10th August 2007, 09:24 AM

IMHO for measuring jitter one needs a test set with much lower jitter specs than the signal to be measured. I doubt any soundcard has better jitter than the master clock in the CD player.

In terms of FFT, both the jitter of the analyzer's timebase and the jitter of the measured signal will have the same effect: the spectral line will have noise sidebands (it will become thicker at the base). It is not possible to separate the contribution of the two.

9th August 2007, 10:10 AM	#1
gaetan8888 diyAudio Member Join Date: Apr 2007	Is there any test cd to test jitter using a scope ? Hello Is there any test cd to test jitter on a cd player by using a scope ? Thank Gaetan

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9th August 2007, 01:34 PM	#2
oshifis diyAudio Member Join Date: Mar 2004 Location: Budapest, Hungary	Test the DAC latch enable signal with a scope. The jitter you get there is the jitter of the system.

9th August 2007, 07:15 PM	#3
martin clark diyAudio Member Join Date: Jul 2003 Location: Bath, UK	Take a read through the works of the late Julian Dunn over at www.nanophon.com An oscilloscope is no way to observe or measure jitter - because the 'scope's internal timbase is far worse. This means that you don't observe jitter directly on a scope, but an intermodulation product between the two timebases...

10th August 2007, 07:57 AM	#4
gaetan8888 diyAudio Member Join Date: Apr 2007	Hello Yes, I seen that a scope don't do the job. But I did found a 16bit/44.1kHz JTEST signal wave file. Made of a 11025Hz square wave with 229.6875Hz LSB. So I did burn a cd with that signal and use it with my Denon DCM-420 cd player, and I use my sound card and a FFT software who go down to -140 db, the result seem good since my Denon have a jitter at -90db from the 11025Hz signal 0 db. Gaetan

10th August 2007, 09:24 AM	#5
oshifis diyAudio Member Join Date: Mar 2004 Location: Budapest, Hungary	IMHO for measuring jitter one needs a test set with much lower jitter specs than the signal to be measured. I doubt any soundcard has better jitter than the master clock in the CD player. In terms of FFT, both the jitter of the analyzer's timebase and the jitter of the measured signal will have the same effect: the spectral line will have noise sidebands (it will become thicker at the base). It is not possible to separate the contribution of the two.

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