> The project is a teletext data encoder which takes an existing video stream,
> extracts the sync pulses, calculates when and where to place the data, and
> then.. places it. Unfortunately I was a factor of 10 out ( doh! ). The data
> rate I need is about 6.9Mbits per second (or 144ns per bit), the protocol
> doesnt use start or stop bits, but synchronises the serial clock at the
> beginning of every scan line by sending binary 1010101010101010 for the
> clock and then another 8 bits to get the framing reference.. 11000100 or
> something like that. The actual data layer of the protocol uses hamming
> codes for a couple of important pieces of data, not everything needs to be
> encoded, and it can be done in advance rather than on the fly- probably the
> best way to do it.

Oh, so it isn't 6.9 Mbps continuous.  How many scan lines in the video
frame need to be encoded?  How much actual data is there per line?

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