I use AVC core on adau1442 ,want to know exact delay time from input to output I2S data. 48Khz sample rate , no SRC. I know at least 4 sample periods delay by reading the pdf,but no idea about processing delay.
Here is my project.
I was pulled into several high-priority, time-critical projects at work over the past few weeks and unfortunately I had to de-prioritize my participation in the forum as a result. So, I apologize for making you wait so long for an answer. I am going to try to respond to everybody's questions within the next few days.
Each cell in SigmaStudio can potentially induce delay into the system.
Sometimes this is linear delay (also known as group delay), which affects all frequencies equally. Examples of group delay would be the fixed delay in hardware between the serial ports and the DSP, or one of SigmaStudio's Delay cells.
Sometimes this is frequency-dependent delay, also known as phase distortion or phase-frequency distortion, which occurs when a filter's phase response is not linear over the frequency range. Almost any filter implemented in SigmaStudio will have some sort of nonlinearity that will introduce phase distortion to the output.
The best way I can think of to approximate the total system delay is to use a white noise source and rapidly turn it on and off. You can check the distance between the edges of the input and output signals when the source is turned on and off. Since the system's delay may be frequency-dependent, the delay times may vary slightly, but you will see that the delay times will all fall within the same average duration.
The delay between input and output will vary with your schematic, specially if you add a delay block in your signal path. We can only guarantee a minimum processing delay and I believe this is what was mentioned in the pdf that you are refering.
Does this answer your question?
Thanks,your replay help me a lot.
Thanks for your help,I have sloved it.you can see my topic on EZ.Thanks again!
杨鹏程 PengCheng Yang
硬件研发部 Hardware R&D Department
Beijing Ideapool Digital Inc.
Tel: 010-64718856 Fax: 010-64718856 Mobile: 13811688774
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发送时间： 2011-12-14 02:56:52
收件人： YANG PENGCHENG
主题： New message: "How to calculate the delay timefor processing audio data on adau1442"
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How to calculate the delay time for processing audio data on adau1442
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I have measured the delay of my projrct, method just like you suggested.I gave 2 periods of square wave on the ADC,and check out the output of DAC.The result is less than 1ms,which is stand for the phase difference.
Thanks for your replay.
发送时间： 2011-12-15 05:17:31
reply from BrettG in SigmaDSP Processors - View the full discussion
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