Originally Posted by slykens
WPSX was feeding the ATSC transmitter in Clearfield directly with the PBS-HD feed there. The transmitter on Pine Grove is part of a Single Frequency Network and from all appearances appears to be functioning properly. It only transmits what is being fed to the Clearfield transmitter in very near synchronization. I checked things last night and saw an appropriate ATSC stream comprised of one 6 Mbps video stream and several audio streams. If the Pine Grove transmitter was passing null data it would have wiped out the signal from Clearfield and I wouldn't have had anything.
What you wrote is true in theory but...
Let me preface this by saying that I'm an engineer working on OTA DTV - which is to say, I have a pretty good idea what I'm talking about. In fact, I'm working on how to determine, at the hardware level, what makes an OTA DTV signal "good" or "not good". I'm looking at bit error rates, equalizer tap values (a multipath indicator) and other such minutiae using both ATI and Oren (now Zoran) demodulator evaluation/development boards. Both boards show nothing but carrier out of Pine Grove.
If this particular DTXn (Distributed Transmission network, first in the US I believe) did not have a few characteristics that make it an exception, what you say above would be entirely correct. Where are you located by the way?
As pointed out in the May 15, 2003 Broadcast Engineering
"WPSX’ experimentally licensed DTX transmitter site in Clearfield takes advantage of some terrain shielding in the State College area to eliminate possible signal interference outside tolerable levels, so it was a natural for DTX..."
Basically, State College can't see diddly-squat of what's broadcast in Clearfield and vice versa. Especially at the low power levels - when they maximize that can change. But even then, the Longley-Rice models don't predict much of a problem.
If you want to know more, look at the excellent WPSX DTXn case history in "ATSC Recommended Practice: Design Of Synchronized Multiple Transmitter Networks", 3 September 2004, available from ATSC. There's also some good technical info at SMPTE.
I don't know when WPSX moves into their new studios but I am sure the new STL is ATSC capable. The equipment is on the roof at Innovation Park, I just don't know when the plan to or if they have lit it.
The move was delayed by several problems, not least of which was re-pouring the studio floor. You'd get seasick watching if they moved cameras on live action! They're actually moving today, even as we speak. The move is going to take quite a while.
They are being carried by PPTN until sometime in July I think. The Clearfield STL at Inno. Park is likely non-functional at the moment.
The Pine Grove LINK isn't (wasn't) ATSC format. I don't know whatit actually was - probably an older, digitally encoded microwave link, those things have been around for ages. Anyway, what's on the link is not ATSC but is modulated in ATSC format at the transmitter. The LINK ITSELF does not have enough bandwidth to deliver an HD feed. That's why even when the Pine Grove STL was up and they were running the national PBS HD feed, State College was getting it in SD - it was downconverted at the studio.
And let's try to keep the political discussion out of this forum, its really not an appropriate place for it and I doubt WPSX's technical and programming decisions are intended to "pay us back" for whomever might have won whatever election.
As a WPSX insider's spouse, I've never seen any evidence that technical issues have anything to do elections.
But these days, programming *might* be a different matter. It's certainly more inviting even if inappropriate to bring in politics. The current administration sure is doing their best to inject politics into the situation.