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lost b/w video

Ignacio Linares
Expert 1655 points
Other Parts Discussed in Thread: TVP5147

My customer is using a TVP5147M1PFP which is attached to a DM6467.  The camera they use is an infrared camera from DRS Technologies which provides RS-170 black/white output to the TVP5147.  I am fairly certain the resolution is 640x480.  Suddenly, the new batch of cameras they received do not seem to working with the TVP5147/DM6467 - they don't see any video coming through.

They seem to think it may be related to register 0x74h bits 1 and 5 (color burst) because there is a note that this is not availble for B/W video sources. 

Do you think this may be related to the problem?

Can you suggest some things to check and some basic steps to help debug what might be happening?

Is there one set of register settings that work for both B/W and color?

  • 0
    TI__Genius 14317 points

    Ignacio,

    The problem is likely AGC related do to missing burst on the RS-170 B/W input. You have a CVBS input, right (not S-Video Y-C or color difference Y, Pb, Pr)?

    From the Data Sheet:

    The TVP5147 AGC comprises the front-end AGC before Y/C separation and the back-end AGC after Y/C separation. The back-end AGC restores the optimum system gain whenever an amplitude reference such as the composite peak (which is only relevant before Y/C separation) forces the front-end AGC to set the gain too low. The front-end and back-end AGC algorithms can use up to four amplitude references: sync height, color burst amplitude, composite peak, and luma peak. The specific amplitude references being used by the front-end and back-end AGC algorithms can be independently controlled using the AGC white peak processing register located at subaddress 74h. The TVP5147 gain increment speed and gain increment delay can be controlled using the AGC increment speed register located at subaddress 78h and the AGC increment delay register located at subaddress 79h.

    You need to disable (set to 1) the Color Burst A and Color Burst B bits in register 0x74h

  • 0 in reply to Jeffery Pfarr
    Expert 1655 points

    The customer wants to know if by disabling the color burst A and B as indicated in your answer, will that mess up the ability to use a color camera.  His concern is he doesn't know which camera his customer will use.  It might be a b/w camera or a color camera.  He would like to have one configuration that works with both cameras.  Is that possible?

  • 0 in reply to Ignacio Linares
    TI__Genius 14317 points

    Since I don't know the details of your TVP5147/DM6467 system I can't say for sure but disabling those bits for AGC reference should not have an impact if the other AGC reference bits in that register are enabled (sync, composite and luma).