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ADSP21469 SPDIF Rx and Tx latency

Hi all,

I can't find any information on the signal delay that the SPDIF receiver and transmitter introduce.

I assume that the transmitter does not generate signal latency at all, however the receiver should.

So, let's assume the following:

DSP 1 generates a master clock, outputs a signal via ADCs and passes this signal via SPDIF transmitter to DSP2

DSP2 uses the recovered clocks and outputs the received signal via ADC.

Currently, I measure a delay of 3.5 samples at 48 kHz between these 2 analog signals.

But there should be any official information about this, shouldn't it?

Best regards,

Rainer

  • Hi again,

    since there are no responses from AD and I needed some answers, I measured a system with SPDIF receiver and transmitter directly connected at 48 and 96 kHz, finding that the latency introduced by this system is 3.5 samples.

    If somebody has alternative facts, just let me know.

    Regards,

    Rainer

  • Hi Rainer,

    Could you please provide more information about how did you check the latency between SPDIF receiver and transmitter? How your system looks like? Please elaborate on the latency you are talking about.

    Regards,

    Jithul

  • Hi Jithul,

    I have a 21469, feed an AES signal into the SPDIF Receiver, connect DIR_FS_O, DIR_CLK_O, DIR_DAT_O and DIR_TDMCLK_O to the respective inputs of the SPDIF transmitter and grab the output by a measurement system.

    I, then measure the frequency resp. impulse response of this system.

    First, I do a reference measurement of my measurement system by connecting the AES output and input of the measurement system using a wire. Impulse response measurements using this wire, then, show a latency of zero.

    Then, I connect the DSP to the measurement system and measure the impulse response which shows a latency of 3,5 samples.

    Regards,

    Rainer

  • Hi Rainer,

    Thanks for your explanation, do you face any issue with respect to this latency in your system?

    Thanks,

    Jithul 

  • Hi Jithul,

    well, the lower the better. I have to deal with this latency to get the two DSPs in sync and just want to know if this is the lowest I can get.

    Also, I wanted to have an official number for it to be sure to do everything right.

    Best regards,

    Rainer