Satruday, july 28, at 10:50AM I was driving through Westminster Md,
listening to 88.1 FM, Baltimore,and I was getting two copies of the same
sounds, one a second or so delayed compared to the other.

This went on for at least 5 miles, at least 10 minutes.

It was nearly impossible to tell what was being said.

How could this happen?

It's a rural area with no very tall buildings and even if there were a
reflection, it would not reflect at me everywhere along a 5 mile line.

I've been there many times before, usually listening to the same
station, and it never happened before. So I don't think there is a
second station on the same frequency in radio range.


Could it be that the transmitter itself was sending out two copies of
the sound, one second apart?


After about 10 minutes, it stopped and the sound was good again.

On 07/31/2018 04:02 AM, micky wrote:
Satruday, july 28, at 10:50AM I was driving through Westminster Md,
listening to 88.1 FM, Baltimore,and I was getting two copies of the same
sounds, one a second or so delayed compared to the other.

This went on for at least 5 miles, at least 10 minutes.

It was nearly impossible to tell what was being said.

How could this happen?

It's a rural area with no very tall buildings and even if there were a
reflection, it would not reflect at me everywhere along a 5 mile line.

I've been there many times before, usually listening to the same
station, and it never happened before. So I don't think there is a
second station on the same frequency in radio range.


Could it be that the transmitter itself was sending out two copies of
the sound, one second apart?


After about 10 minutes, it stopped and the sound was good again.


Well, to be multipath the echo would have to be coming from 150,000 km
away, so that isn't too likely.

Maybe a repeater that got out of sync?

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

On 7/31/2018 1:02 AM, micky wrote:
Satruday, july 28, at 10:50AM I was driving through Westminster Md,
listening to 88.1 FM, Baltimore,and I was getting two copies of the same
sounds, one a second or so delayed compared to the other.

This went on for at least 5 miles, at least 10 minutes.

It was nearly impossible to tell what was being said.

How could this happen?

It's a rural area with no very tall buildings and even if there were a
reflection, it would not reflect at me everywhere along a 5 mile line.

I've been there many times before, usually listening to the same
station, and it never happened before. So I don't think there is a
second station on the same frequency in radio range.


Could it be that the transmitter itself was sending out two copies of
the sound, one second apart?


After about 10 minutes, it stopped and the sound was good again.


Very likely an out of sync repeater. It looks like they have 2 repeaters.
http://www.wypr.org/your-public-radio-fcc-public-file

On Tuesday, July 31, 2018 at 10:15:41 AM UTC-4, Bob F wrote:
On 7/31/2018 1:02 AM, micky wrote:
Satruday, july 28, at 10:50AM I was driving through Westminster Md,
listening to 88.1 FM, Baltimore,and I was getting two copies of the same
sounds, one a second or so delayed compared to the other.

This went on for at least 5 miles, at least 10 minutes.

It was nearly impossible to tell what was being said.

How could this happen?

It's a rural area with no very tall buildings and even if there were a
reflection, it would not reflect at me everywhere along a 5 mile line.

I've been there many times before, usually listening to the same
station, and it never happened before. So I don't think there is a
second station on the same frequency in radio range.


Could it be that the transmitter itself was sending out two copies of
the sound, one second apart?


After about 10 minutes, it stopped and the sound was good again.


Very likely an out of sync repeater. It looks like they have 2 repeaters.
http://www.wypr.org/your-public-radio-fcc-public-file

Or it could be a problem in the studio itself too.

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

Agreed, but WYPR only simulcasts with one station on 88.1MHz (WYPF):
https://en.wikipedia.org/wiki/WYPR
The station broadcasts on 88.1 MHz on the FM band. Its
studio is in the Charles Village neighborhood of
northern Baltimore, while its transmitter is in
Park Heights. The station is simulcast in the
Frederick and Hagerstown area on WYPF (88.1 FM) and
in the Ocean City area on WYPO (106.9 FM).

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, and that their audio feeds are
adjusted for identical delays. In other words, they're setup for
simulcast. However, that's a guess(tm) because I'm in a rush and
don't have time to read exactly what they're doing.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

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.

Agreed, but WYPR only simulcasts with one station on 88.1MHz (WYPF):
https://en.wikipedia.org/wiki/WYPR
The station broadcasts on 88.1 MHz on the FM band. Its
studio is in the Charles Village neighborhood of
northern Baltimore, while its transmitter is in
Park Heights.

It's about 1200 feet from TV Hill, where almost all the tv xmitters are.

The station is simulcast in the
Frederick and Hagerstown area on WYPF (88.1 FM) and

This doesn't yet solve the current question but it does answer another I
never posted.

WYPR's reception is strong in Baltimore and its suburbs, but west,
northwest, north of the suburbs, or all 3, the reception is weak and
it's actually easier to get the NPR station in DC, maybe 40 miles
farther south. I wrote to YPR about this one time but they
misunderstood my letter.

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. 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.

in the Ocean City area on WYPO (106.9 FM).

I've listened to that too when I'm in southern Delaware.

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?

But the syncing failed for 10 minutes? And it was working other times
I was in on that same road.

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.

and that their audio feeds are
adjusted for identical delays. In other words, they're setup for
simulcast. However, that's a guess(tm) because I'm in a rush and
don't have time to read exactly what they're doing.

Any other ideas since you're back.

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

On Tue, 31 Jul 2018 04:02:46 -0400, micky wrote:

Satruday, july 28, at 10:50AM I was driving through Westminster Md,
listening to 88.1 FM, Baltimore,and I was getting two copies of the same
sounds, one a second or so delayed compared to the other.

This went on for at least 5 miles, at least 10 minutes.

It was nearly impossible to tell what was being said.

How could this happen?

It's a rural area with no very tall buildings and even if there were a
reflection, it would not reflect at me everywhere along a 5 mile line.

I've been there many times before, usually listening to the same
station, and it never happened before. So I don't think there is a
second station on the same frequency in radio range.


Could it be that the transmitter itself was sending out two copies of
the sound, one second apart?


After about 10 minutes, it stopped and the sound was good again.

Well, a one second delay is not possible on the earth - the signal path
would have to be about 500,000 miles.

What I think it could be is two stations running the same program
material (LOTS of stations operate at least part of the day from common
network feeds) and there was a slight delay between the feeds they were
getting. (Most of this network stuff is now handled over the internet.)
But, usually, stations relatively nearby do not operate on the same
frequency.

One other possibility is that somebody at the station goofed and started
TWO instances of the network streaming application, and they were getting
slightly out-of-time buffers. I have done this many times when listening
to material on the internet. The 10 minutes of this might be how long it
took for a nearly listener to get through and report the problem. Or,
the local manager only checks the broadcast every so many minutes to make
sure they are still on the air.

Jon