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LMH1218: Signal Quality is OK, but Video is not shown on SDI monitor

Randy LEE64
Prodigy 30 points
Part Number: LMH1218

Hi, 

I am using LMH1218 and XilinX Kintex 7. 

I measured  eye and jitter using Phabrix Qx.  

Signal quality was OK and Video was shown on Phabrix Qx. 

But on mormal sdi monitor, video was not shown. I tried several different monitors.

I attached measured data on phabrix qx. 

Thanks. 

  • 0
    TI__Mastermind 29655 points
    Hi Randy,

    So that we can help, please help provide some details about your setup:

    1. Do you have a block diagram you can share so that we know where the signal path is going, including what type of cable you are using?

    2. Are you using an LMH1218EVM, and are you able to view the behavior of the LMH1218 through the SigCon Architect GUI?

    3. What pattern are you sending through the LMH1218 when you test with the monitors? Does color bar go through?

    4. Is this problem specific to a data rate (I see 1.5G in your screenshot), or does it occur across all data rates?

    Thanks,

    Michael
  • 0 in reply to Michael Lu (Santa Clara)
    Prodigy 30 points

    Hi Michael,

    1. This is the block diagram

    2. I am not using EVM.

    3. Pattern is just linear Pattern. Y and C is the same from 0x001 ~ 0x3BC. 

      SDI Output is YCbCr 4:2:2 10bit. 

      So Do I need to limit data within range (0x004 ~ 0x3FB)?

    4. I tried 1.5G, 3G Level A and 6G.  All data rates are not working.

    Thanks.

     

  • 0 in reply to Randy LEE64
    TI__Mastermind 29655 points

    Hi Randy,

    Thanks for the information. Based on your feedback, it seems like perhaps there is a data formatting incompatibility between the FPGA and monitor. Since the Phabrix Qx is able to display a video output and identify incoming data, this implies to me that there is no issue with the LMH1218 driving out the data. The LMH1218 is a simple physical device and does not process the incoming signal beyond analog signal conditioning.

    I have a few thoughts about diagnosing this issue:

    1. Can you replicate the same pattern, resolution, and data formatting within the Qx, and use the Qx generator output as the source to the SDI monitor? I am curious about whether the Phabrix Qx is able to display an output on the SDI monitor if the format is the same as what Kintex is currently outputting.

    2. If there is a pattern and data formatting from the Phabrix Qx that works with the SDI monitor, please try matching the formatting coming from the Kintex-7 so that it is the same as the Qx. From there, see if the output from the LMH1218 is recognizable by the SDI monitor.

    Thanks,

    Michael

  • 0 in reply to Michael Lu (Santa Clara)
    Prodigy 30 points

    Hi Michael, 

    Phabrix Qx doesn't have custom pattern generation. It has only internal fixed patterns. 

    I fixed this issue by limiting pattern data values between 0x004~0x3FB. 

    Thanks for your help, micahel,

    Randy.