I need to lock to a standard definition video signal (NTSC or PAL) and generate a line locked pixel clock, H sync, V sync, composite blanking and color subcarrier.
The TVP5150 looks like it can do all of that except recreating the color subcarrier. I can not find any chips in current production that will regenerate color subcarrier.
My thought was to feed the GLCO output of the 5150 into a CPLD, decode the subcarrier frequency there and feed that number to a DSO (digital oscillator) clocked by the pixel clock. I don't know if that will work or not. Plus it doesn't take care of phasing the subcarrier to the original.
Does anybody know if the reset bit in the GLCO signal can be used for this, and if so, how often does that reset happen? If not, is there some other way for me to phase the digital oscillator to the original subcarrier phase? Or some other method of regenerating color subcarrier that is locked to the incoming video.
Also, BTW, there currently doesn't seem to be a way to navigate to the TI video decoders from the "Products" link at the top of all web pages. It is in the section "Semiconductors > Video and Imaging > Video Encoders / Decoders", but there is no "Video and Imaging" section in the Products list anymore.
The video and imaging section is found through TI applications off of the TI home page. Video encoders and Decoders are on the right hand side under product tree. As for your question, I will direct it to someone in the field who can help you.
The genlock GLCO ouput in the TVP5150AM1 has been used primarily in RTC mode 0 (see I2C register 15h) for direct connection to composite video encoders. A typical composite video encoder clocks the Fsc frequency control word transmitted by the TVP5150AM1 into a DDS synthesizer for color subcarrier generation, allowing the encoder to adapt to Fsc and line length variations.
The Fsc control word and Reset bit are updated and transmitted line by line by the TVP5150AM1.
I need to generate a continuous color subcarrier locked to the incoming video.
I am guessing that I could connect a 5150's GLCO output to a CPLD and decode the Fsc number, and then feed that into a DDS chip to get a subcarrier sine wave.
Do you think that if I decode the reset bit and simply reset the DDS (edge triggered) whenever the reset bit is set, that I would end up with subcarrier that is phased to the incoming video? Or would the reset bit need to be delayed and reset the DDS at a specific point within the H blanking interval?
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