On Tue, 18 Jan 2005, Cook, Garry wrote:
There are a number of subtle issues going on here. The basic thing is that a pcHDTV-[23]000 is essentially a one-way modem (I guess that's just the dem then... :). All it does is receive an analog signal and decode its modulation. The digital-to-analog modulation scheme for over-the-air HDTV in the US is 8-VSB, which the pcHDTV-[23]000 cards currently support. The modulation scheme typically used for cable tv systems' "digital cable" is a different type, called QAM. Since it's essentially just reprogramming how to interpret the downconvertered/sampled data, it's essentially a firmware upgrade (assuming computational power isn't an issue). Thus, it's possible to receive "digital cable" with nothing more than the 1-way modem provided by the pcHDTV-[23]000.I've been watching this thread with interest, but have a question regarding statements referring to "over cable". Are we speaking about digital cable, or analog? Forgive me if QAM or some other acronym should easily answer my question. I'm not yet familiar with all of the terms.
That said, many/most digital cable system encrypt the signal. So, while the QAM demodulator can receive the bitstream, it's encrypted and cannot be played without decrypting it.
Hope that helps, -Cory
************************************************************************* * Cory Papenfuss * * Electrical Engineering candidate Ph.D. graduate student * * Virginia Polytechnic Institute and State University * *************************************************************************
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