Jitter meter

andrei · 28th August 2003, 09:14 PM

After completion of my latest DAC project, I am pondering new and exciting ways to waste my spare time

.
I am thinking about building something to measure audio-band jitter in digital audio interfaces. (People always talk about jitter here, but there hardly any measurements to go with the talk

. )

This is how I see it:

DIR1703 in bare-bones configuration recovers interface clock from digital input (Toslink or coax). Local VCXO is phase-locked to the recovered MCLK from DIR with fairly wide PLL loop bandwidth (10kHz). Jitter in audio frequency band is demodulated by PFD detector (ADF4001, probably) and is now present on the control input of the VCXO. Amplified jitter signal is measured by an ADC, after which RMS or spectrum can be calculated by an MCU and output on a display (or you can send analog signal straight to headphones for subjective evaluations).

Any thoughts?

JOE DIRT® · 28th August 2003, 10:12 PM

interesting....but you have too much time on your hands to think about it..LOL

If you come up with a written theory and working circuit I will submit it on your behalf for recognition to the WATT

Cheers!! The DIRT®

28th August 2003, 09:14 PM	#1
andrei diyAudio Member Join Date: Dec 2002 Location: Canada	Jitter meter After completion of my latest DAC project, I am pondering new and exciting ways to waste my spare time . I am thinking about building something to measure audio-band jitter in digital audio interfaces. (People always talk about jitter here, but there hardly any measurements to go with the talk . ) This is how I see it: DIR1703 in bare-bones configuration recovers interface clock from digital input (Toslink or coax). Local VCXO is phase-locked to the recovered MCLK from DIR with fairly wide PLL loop bandwidth (10kHz). Jitter in audio frequency band is demodulated by PFD detector (ADF4001, probably) and is now present on the control input of the VCXO. Amplified jitter signal is measured by an ADC, after which RMS or spectrum can be calculated by an MCU and output on a display (or you can send analog signal straight to headphones for subjective evaluations). Any thoughts?

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28th August 2003, 10:12 PM	#2
JOE DIRT® diyAudio Member Join Date: Apr 2003 Location: Brantford, ON	interesting....but you have too much time on your hands to think about it..LOL If you come up with a written theory and working circuit I will submit it on your behalf for recognition to the WATT Cheers!! The DIRT®