On Tue, 31 Jul 2018 16:16:40 -0400, micky
wrote:
In alt.home.repair, on Tue, 31 Jul 2018 07:50:24 -0700, Jeff Liebermann
wrote:
On Tue, 31 Jul 2018 07:12:49 -0700, Bob F wrote:
Very likely an out of sync repeater. It looks like they have 2 repeaters.
http://www.wypr.org/your-public-radio-fcc-public-file
You almost convinced me of this, but Jeff reminded me... and then what
he said convinced me you are right too.
Well, I did make a few minor mistakes. The terms "repeater",
translator", and "simulcast" have very specific meanings, which I
managed to mangle. Part of the problems is that I don't know what
WYPR is doing with both transmitters on 88.1MHz. Are they simulcast
transmitters, or is WYPF a repeater? Dunno and still to lazy/busy to
do the research.
This doesn't yet solve the current question but it does answer another I
never posted.
Sorry, but my crystal ball is being overhauled and I can't provide
answers to unasked questions without it.
WYPR's reception is strong in Baltimore and its suburbs, but west,
northwest, north of the suburbs, or all 3, the reception is weak...
These might help:
https://radio-locator.com/info/WYPR-FM
https://radio-locator.com/cgi-bin/patg?id=WYPR-FM
https://radio-locator.com/info/WYPF-FM
https://radio-locator.com/cgi-bin/patg?id=WYPF-FM
https://radio-locator.com/info/WYPO-FM
https://radio-locator.com/cgi-bin/patg?id=WYPO-FM
Notice that the Google Maps are gone, thanks to a Google fee increase.
So a few weeks ago I was south of Hagerstown, which is 70 miles or so
west of Baltimore, and amazed to get WYPR. Now I realize I was getting
WYPF, only 20 miles away.
If they were really simulcasting (phase locked RF and audio), you
would not be able to tell which one you were listing to.
I knew about that station but not that it
was on the same frequency. There are occasional announcements about all
the stations that play the same programming, but they don't include the
frequencies.
They should include the frequencies with the station identification.
We have several local conglomerations of stations that take quite a
while to identify all the stations that are simulcasting the same
programming. For example:
https://www.kdfc.com/listen/kdfc-coverage-maps/
However, each of the 5 transmitters are on different frequencies.
For a generic FM broadcast receiver, capture effect requires that one
signal is 2dB more than the other in order to get a 30dB of reduction
in "noise" from the weaker station. If the two signals are roughly
equal at the receiver, then you'll get no isolation and hear both
stations. Since KYPR and WYPF are both on 88.1 and fairly close to
each other, my guess(tm) is that their transmit frequencies are both
phase locked to some common reference,
Is that because if they weren't, one could be a half wave out of sync,
and where both could be received, one would cancel out the other?
Yep, or something like that. Without phase locked simulcasting of the
transmitters, there would be a large number of dead spots and possibly
some low frequency heterodyne tones.
But the syncing failed for 10 minutes? And it was working other times
I was in on that same road.
The fact that you were moving is important. If the signal levels from
each transmitter was roughly equal, you would be moving through zones
where one or the other transmitter is stronger and "captures" the
transmitter with the lesser signal. Since you were moving, the
strongest transmitter will switch back and forth between the two
stations erratically. Since something failed on the audio delay
system, every time your receiver switched between the two stations,
the audio would change accordingly.
It turns out I was only 27.6 miles from the WYPF transmitter:
?hl=en
And it's 25.2 miles from the YPR xmitter. Part of the time, since I was
moving, the distances were even closer.
So, it's likely that the signal levels were roughly the same, which is
ideal for creating the problem.
Any other ideas since you're back.
Nope.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558