On Wed, 1 Aug 2018 05:13:48 -0700 (PDT), "
wrote:
Y'all are making this far too complicated and inventing explanations other
than a simple sync issue within the station itself. Could be as simple as
a tech replacing a piece of equipment and dropping a jumper into the
wrong jack. 10 minutes later - after the phones started ringing off
the hook - it got fixed.
I doubt if more than few listeners heard the problem. In order to
hear both transmitters switching back and forth, the listener would
need to be:
1. Roughly equal distant from both stations or in an area where the
signal strengths are about the same.
2. In a moving vehicle, train, bus, or whatever.
3. Have a cell phone handy with which to phone the station.
4. Have a web browser handy to lookup the phone number:
http://www.wypr.org/contact-us
5. Be sufficiently experienced with such problems to be able to
explain the problem to the low technical level person who answers the
phone, and at a high level should someone be available that
understands the problem.
6. Be able to explain why the various OTA station monitors show that
everything is just fine and both transmitters are on the air.
7. Be able to explain why so few other people have called in the
problem. I've found that stations do not act on such things unless
there are a large number of calls, or they get a call from a sponsor.
William of Occam suggested that we eschew needless complexity.
He was wrong. Todays fashion is to target one's writing to the lowest
level of intelligence and expertise that one might expect the document
to be read. If someone is writing for a engineers with FM broadcast
experience, it would look very different if they were writing for the
GUM (great unwashed masses). The best advice I've seen is to write
for those that are competent in their field of expertise, not
necessarily in yours.
In this case, the problem isn't very complicated to understand if one
has some experience with FM capture effect, simulcast techniques, FM
simulcast, repeaters, translators, FCC FM 60dBu contours, digital vs
analog FM receivers, and possibly how HD Radio works.
I didn't mention the possible HD RADIO problem because I thought it
was unlikely. Yet the symptoms are similar. WYPR broadcasts on 88.1
(main FM channel), 88.1-1 (HD1 news and talk), 88.1-2 (HD2 BBC world
news), and 88.1-3 (HD3 classical music). During commercial breaks and
other interruptions, stations sometime fill in the dead air with audio
from one of the digital sub-channels. There is a delay between the
main analog FM audio and the delayed digital version, in this case on
HD1. Stations with this arrangement usually have some way to adjust
this delay so that switching between the analog audio and HD1 does not
result in an obvious delay. If the listener is in a moving vehicle,
and has the radio switched to HD1, the signal will drop out on HD1 in
fringe areas causing the receiver to revert back to the main FM audio.
This is particularly irritating because many HD Radio receivers do not
have a setting that forces the receiver to stay on HD1 and not switch
to the main analog channel. It's possible that this might have been
the problem, but I can't tell from here without more details.
So, what have we learned here?
1. Simple explanations are fine for the GUM but not so useful if you
want to understand what had happened and how it works.
2. If you want to understand something, you have to dig deep, really
deep.
3. RF is magic.
4. Nothing is simple.
5. If something seems too complicated, ask questions or Google for
understanding. Don't just complain that it's too complexicated.
Peter Wieck
Melrose Park, PA
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558