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Re: [Discuss-gnuradio] Hardware costs

From: Hermann Gausterer
Subject: Re: [Discuss-gnuradio] Hardware costs
Date: Fri, 14 Mar 2003 13:53:05 +0100
User-agent: Mutt/1.2.5i

On Thu, Mar 13, 2003 at 08:15:54PM -0700, Mike wrote:
> I haven't written any code using the BT848/878 chips, but I did spend
> some time going over the spec sheets with the idea of raw analog
> sampling in mind.  

what do you think about the "Vertical Blanking Interval Data Capture"

-----------------------from the datasheet----------------------
The Bt879 provides a complete solution for capturing and decoding VBI 
data. The Bt879 can operate in a VBI Line Output Mode, in which the
VBI data is only captured during select lines. This mode of operation 
enables concurrent capture of VBI lines containing ancillary data and 
normal video image data. In addition, the Bt879 supports a VBI Frame 
Output Mode in which every line in the video frame is treated as if 
it was a VBI line. This mode of operation is designed for use with 
still frame capture/processing applications.

The captured data stream is continuous and not aligned with HSYNC.

looks like a capture mode for every line of a frame,
should also work with Y/C :-)

> There might be some tricks that could be played with, say, the svideo
> input by putting the RF signal on the chroma channel and putting the
> appropriate sync pulses on the luminance channel. 

i think this "could" work, but the problem with the VBI capture will
be that this is disigned for a "single shot" of one frame, after this
frame the capture is automaticaly stoped ( in my opinion ), a restart
will result in gaps with no sampling data


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