900 mhz video transmitter VIDEO PROBLEM

Discussion in 'The Projects Forum' started by BIGPISCIOTTA, Dec 3, 2012.

  1. BIGPISCIOTTA

    Thread Starter New Member

    Dec 3, 2012
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    I just finshed building my 900mhz transmitter frequency is ok when i connect my video camera into the transmitter i get a herringbone pattern . I belived that its a grown loop problem . How can correct this problem
     
  2. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    Maybe your circuit is oscillating.
    you forgot to attach your schematic so we cannot help you.
     
  3. BIGPISCIOTTA

    Thread Starter New Member

    Dec 3, 2012
    14
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    can a growh loop in 900mhz video transmitter cause herringbone pattern
    herringbone only when the external video camera c0onnected
     
  4. DickCappels

    Moderator

    Aug 21, 2008
    2,648
    632
    Yes. Herring Bone patterns result when an interfering signal beats with another, such as the frame rate or the line rate. Such things happen when power supply noise or other periodic signals get into the video (such as spurious oscillations).

    Would you please show your schematic and maybe somebody can spot the area in which you are likely to find the problem.
     
  5. BIGPISCIOTTA

    Thread Starter New Member

    Dec 3, 2012
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    Attached is a copy of my 900mhz video transmitter
     
  6. DickCappels

    Moderator

    Aug 21, 2008
    2,648
    632
    Thank you.
    Can you post the file in an internet browser-friendly format such as GIF, TIFF, or PNG?
     
  7. BIGPISCIOTTA

    Thread Starter New Member

    Dec 3, 2012
    14
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    i beleive its in tiff
     
  8. BIGPISCIOTTA

    Thread Starter New Member

    Dec 3, 2012
    14
    0
    attached is tiff file for 900mhz tx
     
    Last edited: Dec 4, 2012
  9. BIGPISCIOTTA

    Thread Starter New Member

    Dec 3, 2012
    14
    0
    attachment 900mhz
     
  10. BIGPISCIOTTA

    Thread Starter New Member

    Dec 3, 2012
    14
    0
    I just finished a 900 mhz video tx every thing works fine clear picture. When i install in a metal enclosure i get herring bone pattern . I beleive that it being caused by pcb board dielectric. How can i correct this problem
     
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