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Altera_Forum's avatar
Altera_Forum
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15 years ago

Problem with ALTGX

Hello All,

I'm having a problem with ALTGX transceivers. The problem is the follow:

I'm Using a transceiver that it's suppose to run at a datarate of 2.970 Gbps (3G-SDI). I'm using this transceiver to transport SD-SDI which runs at 270Mbps using a oversample scheme. However when I put the oscilloscope at the transceiver output (270Mbps) i cannot see anything similiar with a signal. Instead i see sine wave. Even when i do the TX DIGITAL RESET the output is a sine wave with a frequency that is not familiar at all.

Please help me if you can.

Best regards

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    Despite the fact that your serialization factor (11) sounds a bit strange (I would rather expect 20, 10, 16 or 8), I assume your firmware is OK.

    In that case, You should observe an eye pattern (338ps width).

    If you observe a sine wave, it sounds like:

    1) the TX delivers 01010101... instead of NRZ data

    2) your scope does not offer a sufficient bandwith (6GHz would be the limit, 12GHz would be fine) or is not properly configured (set a suitable display persistence notably)

    Do you have any screenshot ?
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    The oversampling serialization factor of 11 is correct. This is typical for mixed 3G/SD-SDI video.

    What you are saying is that you are not seeing what you expect on the output. What is the sampling rate of our oscilloscope? Are you sure you're seeing a sine-wave or just the positive edge triggered data of the NRZI encoded data?

    Jake