Screen size should be irrelevant. There was a large flat-screen TV divided into four segments: the output of the 5th-generation LG receiver, the outputs of the two MPH prototype receivers, and a spectrum analyzer. Everything was SD. When the main signal failed, it was pretty obvious -- no need to see macroblocks. The robust sub-channels were low quality, but they're limited only by what can be encoded and decoded into that data rate. Harris and LG are not making the encoders (at least not yet).
Actually, there's an error in my previous message. The quarter-rate subchannel did take one hit in a sort of tunnel.
TTFN, Mark John Willkie wrote:
Mark; Screen size? Apparent quality of the video? John Willkie----- Original Message ----- From: "Mark Schubin" <tvmark@xxxxxxxxxxxxx>To: "Open DTV Forum" <opendtv@xxxxxxxxxxxxx> Sent: Monday, April 16, 2007 10:04 PM Subject: [opendtv] Ride in the Harris-LG MPH busTransmission was from Sinclair's KVCW, channel 29, broadcasting from Black Mountain at 750 kW ERP at 1086 feet HAAT. Two 2.2 Mbps sub-channels were used for the robust transmission leaving 15 Mbps for the main transmission. One sub-channel, using "half-rate" transmission, had a payload of 557 kbps; the other, with "quarter rate," had 299 kbps. MPEG-4 AVC coding was used for those sub-channels. The antenna was one 6-inch untuned whip split four ways It was interesting to me that the main channel failed when the bus was barely creeping. FYI, it was using a 5th-generation LG receiver. Sometimes it seemed okay at speed. The "half-rate" sub-channel took a few hits in the worst reception conditions. I take their word for it that the "quarter-rate" sub-channel never took a hit (the decoder, however, froze). The white-noise threshold is said to be 8 dB for the half-rate channel and 4 dB for the quarter-rate. I'm told the A-VSB demo also uses two 2.2 Mbps robust sub-channels. Their "half-rate" is about 1 Mbps and "quarter-rate" about 500 kbps, but they take a his of another 2.89 Mbps for the SRS signal. TTFN, Mark ---------------------------------------------------------------------- You can UNSUBSCRIBE from the OpenDTV list in two ways: - Using the UNSUBSCRIBE command in your user configuration settings atFreeLists.org- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the wordunsubscribe in the subject line.----------------------------------------------------------------------You can UNSUBSCRIBE from the OpenDTV list in two ways:- Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word unsubscribe in the subject line.
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