Signal question for all you smart people out there

[another_guy]

I was at a cookout in hudson, nh this weekend and was talking to my brother inlaw, and he was asking me some technical radio stuff.

He likes to listen to WTKK, and he told me whenever he is in the manchester area he'll be listening and all of a sudden WTKK will switch to some country station, thats clear as day, then go back to WTKK. he says its weird becuase there is no static, it just flips. He thought maybe he was picking up an HD channel, but his radio is so old and doesn't have an HD reciever so I really doubt thats what he's doing.

It got me curious though and was wondering if any of you might have the answer. I assume he's just picking up another station, maybe from up north, but its weird that it just flips over without static

 

[weee]

There's a country station out of Dover at 97.5, since 'TKK is 96.9, maybe it's close enough to "seep" in?

 

[CTListener]

There's a country station out of Dover at 97.5, since 'TKK is 96.9, maybe it's close enough to "seep" in?

That must be one awful, cheap radio he's using. A 97.5 signal from the seacoast shouldn't be wiping out a 96.9 signal from Boston in Manchester under any circumstances.

One possibility, though remote, is that someone has a satellite radio FM modulator in operation in the area, perhaps hooked up to an illegal amplifier or antenna, and is pumping out an XM or Sirius country channel on 96.9. I've heard of Sirius subscribers doing this to get Howard Stern's show out to a bigger audience.

 

[raccoonradio]

WOKQ has a repeater at 97.9 in Manchester, NH

From radio-locator:
W250AB (WOKQ) 97.9 FM Manchester, NH Country

coverage map of 97.9
http://radio-locator.com/cgi-bin/pat?call=W250AB&service=FX&status=L&hours=U

 

[Eli Polonsky]

He likes to listen to WTKK, and he told me whenever he is in the manchester area he'll be listening and all of a sudden WTKK will switch to some country station, thats clear as day, then go back to WTKK. he says its weird becuase there is no static, it just flips. He thought maybe he was picking up an HD channel, but his radio is so old and doesn't have an HD reciever so I really doubt thats what he's doing.

It got me curious though and was wondering if any of you might have the answer. I assume he's just picking up another station, maybe from up north, but its weird that it just flips over without static

If his receiver is old, it may have a built-in AFC (Automatic Frequency Control), and less than optimal selectivity. Those AFC circuits often used to simply pull a stronger station nearby on the dial right over a weaker station on the frequency tuned to, and they would often do it suddenly, without static. It was an extremely annoying feature in those radios. This is probably what's happening when your friend gets close to WOKQ's Manchester repeater.

The only other possibility is that if it's only happening in a very small area, someone may have a satellite radio transponder (such as for XM or Sirius) set to rebroadcast on 96.9 (or thereabouts) and is listening to a satellite country station.

 

[WLYNWAZNgm]

Since FM signals are more line-of-sight than AM signals, antenna height above the average terrain is more critical.
With the hills/mountains in NH, conditions for receiving a particular signal can change , depending on which side of the mountain you're on, at any given time. Cell phones are even more pronounced: you can have zero signal one minute, and 100 % signal a short distance away...

 

[CTListener]

He likes to listen to WTKK, and he told me whenever he is in the manchester area he'll be listening and all of a sudden WTKK will switch to some country station, thats clear as day, then go back to WTKK. he says its weird becuase there is no static, it just flips. He thought maybe he was picking up an HD channel, but his radio is so old and doesn't have an HD reciever so I really doubt thats what he's doing.

It got me curious though and was wondering if any of you might have the answer. I assume he's just picking up another station, maybe from up north, but its weird that it just flips over without static

If his receiver is old, it may have a built-in AFC (Automatic Frequency Control), and less than optimal selectivity. Those AFC circuits often used to simply pull a stronger station nearby on the dial right over a weaker station on the frequency tuned to, and they would often do it suddenly, without static. It was an extremely annoying feature in those radios. This is probably what's happening when your friend gets close to WOKQ's Manchester repeater.

Except the repeater's on 97.9 and he's listening to 96.9.

 

[Eli Polonsky]

Except the repeater's on 97.9 and he's listening to 96.9.

That's why I said that his radio "may have less than optimal selectivity" and an AFC circuit. If he's right near the 97.9 transmitter, it may cover up a station 50 miles away even from 1 mHz apart on the dial on a radio with really poor selectivity (such as many Walkmans and Boom-boxes, clock radios, older cheap portables, and older cheap brands of analog car stereos)

 

[Smoke]

He likes to listen to WTKK, and he told me whenever he is in the manchester area he'll be listening and all of a sudden WTKK will switch to some country station, thats clear as day, then go back to WTKK. he says its weird becuase there is no static, it just flips. He thought maybe he was picking up an HD channel, but his radio is so old and doesn't have an HD reciever so I really doubt thats what he's doing.

It got me curious though and was wondering if any of you might have the answer. I assume he's just picking up another station, maybe from up north, but its weird that it just flips over without static

If his receiver is old, it may have a built-in AFC (Automatic Frequency Control), and less than optimal selectivity. Those AFC circuits often used to simply pull a stronger station nearby on the dial right over a weaker station on the frequency tuned to, and they would often do it suddenly, without static. It was an extremely annoying feature in those radios. This is probably what's happening when your friend gets close to WOKQ's Manchester repeater.

The only other possibility is that if it's only happening in a very small area, someone may have a satellite radio transponder (such as for XM or Sirius) set to rebroadcast on 96.9 (or thereabouts) and is listening to a satellite country station.

On my cassette late 90s Sony Walkman I would sometimes get Hanscom airplane transmissions in place of 96.9. Could this be AFC?

 

[Eli Polonsky]

On my cassette late 90s Sony Walkman I would sometimes get Hanscom airplane transmissions in place of 96.9. Could this be AFC?

Sounds more like probably poor IF (intermediate frequency) rejection. The VHF aircraft band is directly above the FM broadcast band in the spectrum, and the Hanscom frequency may have been approximately 10.7 mHz above 96.9, creating an IF image of their transmissions 10.7 mHz below their actual frequency in the receiver if you were nearby. A better receiver would filter that out.

 

[ngriffin]

Most likely, it's another station on 96.9 with a country format that is putting a weak signal into the area due to tropospheric scatter (this is what brings stations 100-300 miles away frequently in the morning or evenings). When the Boston signal weakens, the weaker one overrides it. The most likely possibility is Presque Isle, Maine with 100,000 watts. Less likely is a translator on 96.9 in Portland, Maine