[SBE] ATSC Tuner Differences

[Gibson Prichard]

My station has our primary signal on a low-VHF channel (5) and we
operate a fill-in translator on UHF channel 50 that was formerly
occupied by an NTSC station in the market. That station is now on a
different UHF channel (33), but their PSIP rightly shows them with
their old NTSC channel for their major #, followed by 1 though 5 for
their 5 program streams (e.g. 50-1 through 50-5). Following the ATSC
guidelines, minor channel 1 is MPEG program # 3, .2 is MPEG #4, all
the way to their .5 stream is MPEG program #7. My station's PSIP is
also correct, showing major channel 5 with three minor channels (1
through 3, corresponding to MPEG programs 3 through 5).

We have several odd scenarios resulting from using their old NTSC
channel. The first issue is that some set-top boxes will lock onto
their RF signal and give the viewer their .1 and .2 streams, however,
when a viewer tries to tune to that station's .3, .4 or .5 stream,
they get my station's translator with our .1 channel showing up as
50-3. I realize that the set-top box is tuning to RF channel 33 and
decoding streams 1 & 2 from the other station, but when the viewer
tries to watch that station's third, fourth or fifth stream, these
boxes refuse and tune to RF channel 50 and decode our MPEG stream #3,
stream #4 & stream #5 in place of theirs. No amount of fiddling or
re-scanning helps the viewer receive the intended 50-3, 4 & 5, unless
they remove the antenna from their box during a re-scan, once it has
scanned RF channel 33 and before it gets to our RF channel 50.
The other scenario, while less troublesome, is that our programs will
show up as 50-6, 50-7 & 50-8 on some boxes, in line after their 5
streams, rather than showing up on 5-1 through 5-3 as they should. If
the viewer can receive the VHF signal, it will show up correctly as
5-1 through 5-3, but the UHF translator signal is sometimes stronger
or more easily received than the VHF, hence the issue.
Still other sets or converter boxes tune 50-1 & 5-2 to be the correct
video (RF33), then 50-3, 4 & 5 are video streams from my station (on
RF 50), followed by 50-6 & 50-7 coming from RF 33. It doesn't take
much of this to confuse the average viewer, as you can see.

I know what "should" happen with ATSC tuners, but real life has shown
us that all bets are off as far uniformity is concerned. Some tuners
do one thing and some do another. Has anyone else experienced this
sort of madness?

Gibson Prichard
Nashville, TN