Multiple frequency interference by WMMR?

[kieren]

I live in CC, and on most of my radios (expensive and cheap), WMMR comes in at multiple places at the bottom of the dial, including stomping all over WHYY at 90.9. I assume this has something to do with the way the signal from Liberty Place ricochets off buildings and other structures. But is there anything I can do to filter it out?

 

[DToTheJ]

I live in CC...

Since when did Clear Channel start offering housing?

Regarding your issue, it is weird how some stations have a tendency to "echo" off frequencies within it on the dial. I don't think it's just Philly.

 

[qtpieislit]

The operative word is multipath.

 

[MikeF]

I live in CC, and on most of my radios (expensive and cheap), WMMR comes in at multiple places at the bottom of the dial, including stomping all over WHYY at 90.9. I assume this has something to do with the way the signal from Liberty Place ricochets off buildings and other structures. But is there anything I can do to filter it out?

It's because WMMR has a much stronger signal than any other station in CC, and it's overloading the "front ends" of your receivers. Theoretically you could put a 93.3 trap on your receivers' antenna inputs, but that's probably not practical. You could also on some of your receivers create a smaller antenna as the input, which will reduce the overload at the expense of not being able to pick up non-local stations.

 

[MarcB]

I live in Connecticut. And I get HOT 93.7 WZMX albeit very distorted on 94.9 FM on my car radio. It's the only station I've noticed this with - not any of the other stations on Meriden Mountain do this.

 

[DanStrassberg]

Since when did Clear Channel start offering housing?

Clear Channel's NYSE (Stock Exchange) ticker symbol, CCU, is less ambiguous and it's only one more character to type. I live 300 miles away, but even I know that CC in the post you referred to was not a reference to Clear Channel but to Center City. Then again, maybe you knew that all along and just couldn't resist a little sarcasm.

 

[nd2023]

I live in Connecticut. And I get HOT 93.7 WZMX albeit very distorted on 94.9 FM on my car radio. It's the only station I've noticed this with - not any of the other stations on Meriden Mountain do this.

2*93.7-92.5=94.9 That explains how you get Hot 93.7 on 94.9. If you listen closely, you'll also hear WWYZ 92.5 on 94.9 intermodulated with 93.7.

 

[1540]

kieren if you have a receiver that has an antenna connection go to a place on the net like affordablehdtv.com and get a 20dB Variable Attenuator for 13 bucks. With the attenuator and a cheep TV rabbit ear antenna you should be able to reduce the front end overload from MMR so you can listen to HYY.

 

[kieren]

Thanks. I take some satisfaction from the fact my gut feeling about the cause was accurate (see below).

Is there a way to make a radio without an external antenna connection work with this solution? I'm decent with a soldering iron and don't mind cracking open my radios since I have plenty of them and so can afford some trial and error. I'm a tinkerer and trial-and-errorer, not a tech or engineer. I would NOT make a very insurable brain surgeon but my record suggests eventually a patient might recover.



affordablehdtv.com
"Terrestrial Digital 20dB Variable Attenuator is intended for those living very close to transmitting towers, problems with multipath interference can occur because the signals are so strong that they bounce off nearby buildings and other objects and cause multiple images to appear on one's TV screen. This attenuator allows users to dial down the signal to reduce problems associated with this multipath interference."

 

[amfmsw]

I believe the word Sam meant was harmonics (but I'm sure there's multipath too). It sounds like your picking up a mathmatical harmonic of 93.3, or the main frequency mixing with another local, forming it's own channel. 103.9 is nearby, yes? Your IF demodulator in the home radio is 10.7Mhz.
103.9 - 93.3 = 10.6...close enough on inexpensive designs to cause problems. Another could be diplex units aren't tuned and trapped properly. Could also be icing on their antenna, causing high VSWR, a problem that will melt away.

 

[1540]

The problem is not harmonics or multipath the problem is not with WMMR the problem is with the receiver. Go to http://www.fanfarefm.com/fm-specs.html and read about Fm radio specifications

 

[aindik]

It's because in Center City you are so close to the WMMR transmitter atop Liberty One. I used to have the same problem in DC. WAVA used to bleed all over everything.

If your radio has a DX/local switch, try switching it to "local."