Re: [Discuss-gnuradio] Status of BTTV/CX88 capture

[Cory Papenfuss]

	I looked through this a bit, and it appears to be pseudo-open. 
Yes, it's all open-source, but the bulk of the interesting stuff is in the 
microcode for the ATSC chip.  That's just page afer page of bytecode, and 
I don't think datasheets are available for it.

	I *do* believe that the CX chip is just doing ADC (and SDTV 
decode).  The cards are allegedly capable of doing QAM, though, so they 
shouldn't *require* VSYNC to work.  I haven't looked through the code to 
try.

	My thought is a cheap cx88-based card would probably provide the 
same options... unless the specs for the atsc chip can be obtained and are 
useful.

-Cory

> > Look at the PCI card by pchdtv.com.  They use the cx23883, plus a canned TV
> > tuner by Thomson.  All the drivers are open source.  It's designed to be
> > an open source compatible HDTV and SDTV interface card.
> I have just today been looking at it.
> Hoped they had the hardware design online but couldn't find it(yet).
>
> I have just contacted the technical guy you pointed out to ask about the 
> details of the design and the driver.
>
> They use a chip to do the atsc decoding.
> With a little hardware mod it should be possible to attach the IF output of 
> the tuner to the analog ADC input of the cx2388x.
> (Which is now connected to the atsc decoder chip).
>
> Maybe it is even possible to reprogram the atsc chip to act as just an ADC 
> (and passthrough the undecoded data)
> That all depends on the chip capabilities and the datasheets available.
>
> I hope it is indeed possible to use these boards for gnuradio because they 
> did a good job of creating an open HDTV receiver.
> Too bad we can't use them in europe (digital TV here is DVB in stead of atsc 
> and 8Mhz channels in stead of 6 Mhz)
> If we hack them to be usable for gnuradio it might still be possible (with an 
> 8Mhz tuner)
> > I have five of these cards lying around, so if you write code that
> > makes them useful for GNU Radio, I can provide cards to Eric & Matt...
> That's cool.
>
> greetings,
> Martin
>
>
>
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--

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* Cory Papenfuss                                                        *
* Electrical Engineering candidate Ph.D. graduate student               *
* Virginia Polytechnic Institute and State University                   *
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